WorldWideScience

Sample records for magnetic split-flow thin

  1. Concentric Split Flow Filter

    Science.gov (United States)

    Stapleton, Thomas J. (Inventor)

    2015-01-01

    A concentric split flow filter may be configured to remove odor and/or bacteria from pumped air used to collect urine and fecal waste products. For instance, filter may be designed to effectively fill the volume that was previously considered wasted surrounding the transport tube of a waste management system. The concentric split flow filter may be configured to split the air flow, with substantially half of the air flow to be treated traveling through a first bed of filter media and substantially the other half of the air flow to be treated traveling through the second bed of filter media. This split flow design reduces the air velocity by 50%. In this way, the pressure drop of filter may be reduced by as much as a factor of 4 as compare to the conventional design.

  2. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  3. Thin Magnetically Soft Wires for Magnetic Microsensors

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2009-11-01

    Full Text Available Recent advances in technology involving magnetic materials require development of novel advanced magnetic materials with improved magnetic and magneto-transport properties and with reduced dimensionality. Therefore magnetic materials with outstanding magnetic characteristics and reduced dimensionality have recently gained much attention. Among these magnetic materials a family of thin wires with reduced geometrical dimensions (of order of 1–30 μm in diameter have gained importance within the last few years. These thin wires combine excellent soft magnetic properties (with coercivities up to 4 A/m with attractive magneto-transport properties (Giant Magneto-impedance effect, GMI, Giant Magneto-resistance effect, GMR and an unusual re-magnetization process in positive magnetostriction compositions exhibiting quite fast domain wall propagation. In this paper we overview the magnetic and magneto-transport properties of these microwires that make them suitable for microsensor applications.

  4. Magnetization in permalloy thin films

    Indian Academy of Sciences (India)

    Rachana Gupta; Mukul Gupta; Thomas Gutberlet

    2008-11-01

    Thin films of permalloy (Ni80Fe20) were prepared using an Ar+N2 mixture with magnetron sputtering technique at ambient temperature. The film prepared with only Ar gas shows reflections corresponding to the permalloy phase in X-ray diffraction (XRD) pattern. The addition of nitrogen during sputtering results in broadening of the peaks in XRD pattern, which finally leads to an amorphous phase. The - loop for the sample prepared with only Ar gas is matching well with the values obtained for the permalloy. For the samples prepared with increased nitrogen partial pressure the magnetic moment decreased rapidly and the values of coercivity increased. The polarized neutron reflectivity measurements (PNR) were performed in the sample prepared with only Ar gas and with nitrogen partial pressure of 5 and 10%. It was found that the spin-up and spin-down reflectivities show exactly similar reflectivity for the sample prepared with Ar gas alone, while PNR measurements on 5 and 10% sample show splitting in the spin-up and spin-down reflectivity.

  5. Magnetic shape memory effect in thin foils

    Science.gov (United States)

    Heczko, Oleg; Soroka, Aleksandr; Hannula, Simo-Pekka

    2008-07-01

    The magnetic shape memory (MSM) effect was observed in Ni-Mn-Ga freestanding thin foils down to 90μm in thickness using top-down approach. The foils were prepared by thinning the bulk crystals exhibiting MSM effect. The effect was evaluated from the magnetization curves. The significant decrease in magnetic field needed to initiate the MSM effect (magnetic field induced strain or martensite structure reorientation) was observed for the studied foils down to μ0H=0.088T or H =70kA/m. Observation suggests that the pinning of twin boundaries on the internal obstacles rather than pinning on surface lowers twin boundaries' mobility.

  6. Structures of magnetized thin accretion disks

    Institute of Scientific and Technical Information of China (English)

    LI; xiaoqing(李晓卿); JI; Haisheng(季海生)

    2002-01-01

    We investigate the magnetohydrodynamic (MHD) process in thin accretion disks. Therelevant momentum as well as magnetic reduction equations in the thin disk approximation areincluded. On the basis of these equations, we examine numerically the stationary structures, includingdistributions of the surface mass density, temperature and flow velocities of a disk around a youngstellar object (YSO). The numerical results are as follows: (i) There should be an upper limit to themagnitude of magnetic field, such an upper limit corresponds to the equipartition field. For relevantmagnitude of magnetic field of the disk's interior the disk remains approximately Keplerian. (ii) Thedistribution of effective temperature T(r) is a smoothly decreasing function of radius with power 1 corresponding to the observed radiation flux density, provided that the magnetic fieldindex γ= -1/2,is suitably chosen.

  7. Magnetically actuated peel test for thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ostrowicki, G.T.; Sitaraman, S.K., E-mail: suresh.sitaraman@me.gatech.edu

    2012-03-30

    Delamination along thin film interfaces is a prevalent failure mechanism in microelectronic, photonic, microelectromechanical systems, and other engineering applications. Current interfacial fracture test techniques specific to thin films are limited by either sophisticated mechanical fixturing, physical contact near the crack tip, or complicated stress fields. Moreover, these techniques are generally not suitable for investigating fatigue crack propagation under cyclical loading. Thus, a fixtureless and noncontact experimental test technique with potential for fatigue loading is proposed and implemented to study interfacial fracture toughness for thin film systems. The proposed test incorporates permanent magnets surface mounted onto micro-fabricated released thin film structures. An applied external magnetic field induces noncontact loading to initiate delamination along the interface between the thin film and underlying substrate. Characterization of the critical peel force and peel angle is accomplished through in situ deflection measurements, from which the fracture toughness can be inferred. The test method was used to obtain interfacial fracture strength of 0.8-1.9 J/m{sup 2} for 1.5-1.7 {mu}m electroplated copper on natively oxidized silicon substrates. - Highlights: Black-Right-Pointing-Pointer Non-contact magnetic actuation test for interfacial fracture characterization. Black-Right-Pointing-Pointer Applied load is determined through voltage applied to the driving electromagnet. Black-Right-Pointing-Pointer Displacement and delamination propagation is measured using an optical profiler. Black-Right-Pointing-Pointer Critical peel force and peel angle is measured for electroplated Cu thin-film on Si. Black-Right-Pointing-Pointer The measured interfacial fracture energy of Cu/Si interface is 0.8-1.9 J/m{sup 2}.

  8. Dynamic Characterization of Thin Film Magnetic Materials

    Science.gov (United States)

    Gu, Wei

    A broadband dynamic method for characterizing thin film magnetic material is presented. The method is designed to extract the permeability and linewidth of thin magnetic films from measuring the reflection coefficient (S11) of a house-made and short-circuited strip line testing fixture with or without samples loaded. An adaptive de-embedding method is applied to remove the parasitic noise of the housing. The measurements were carried out with frequency up to 10GHz and biasing magnetic fields up to 600 Gauss. Particular measurement setup and 3-step experimental procedures are described in detail. The complex permeability of a 330nm thick continuous FeGaB, 435nm thick laminated FeGaB film and a 100nm thick NiFe film will be induced dynamically in frequency-biasing magnetic field spectra and compared with a theoretical model based on Landau-Lifshitz-Gilbert (LLG) equations and eddy current theories. The ferromagnetic resonance (FMR) phenomenon can be observed among these three magnetic materials investigated in this thesis.

  9. Growth Induced Magnetic Anisotropy in Crystalline and Amorphous Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Frances

    1998-10-03

    OAK B204 Growth Induced Magnetic Anisotropy in Crystalline and Amorphous Thin Films. The work in the past 6 months has involved three areas of magnetic thin films: (1) amorphous rare earth-transition metal alloys, (2) epitaxial Co-Pt and hTi-Pt alloy thin films, and (3) collaborative work on heat capacity measurements of magnetic thin films, including nanoparticles and CMR materials.

  10. Magnetic Thin Films of Inorganic Nanosheets

    Science.gov (United States)

    Yamamoto, Takashi; Namba, Hiroaki; Einaga, Yasuaki

    2012-02-01

    Molecule-based magnets have been fascinating materials because of the potential applications in information storage, electronic and spintronic devices. However, such applications would require arraying the active materials on a substrate or interfacing with other components. Here, we focus on fabricating multi-functional magnetic films using inorganic nanosheets as a building block. The thin films could be prepared by the modified Langmuir-Blodgett, LB, technique or the layer-by-layer, LbL, method, which are representative wet-processings for film preparation. As the magnetic LB film, we chose semiconductive titania nanosheets and magnetic Prussian Blue. Upon band gap excitation of titania nanosheets, electron injection into Prussian Blue was achieved with scavenging interlayer water molecules, leading to photoreduction to Prussian White. As the magnetic LbL film, we chose magnetic layered double hydroxide, LDH, nanosheets and non-magnetic smectite nanosheets. In powdered LDH, a coercivity increased with expanding the interlayer spacing. On the other hand, despite the larger interlayer spacing for the LbL film, a coercivity was less than that of the comparative powdered LDH. It is indicated LDH nanosheets are integrated in an anisotropic manner in the LbL films.

  11. 3D Field Simulation of Magnetic Thin Film Inductor

    OpenAIRE

    FUJIWARA, Toshiyasu; CHOI, Kyung-Ku; SATO, SHIGEKI

    2006-01-01

    The 3D magnetic field simulations with FEM (finite element method) have been performed to predictand understand the performance of Magnetic Thin Film Inductor (MTFl). Inductor structures of planar electroplated Cu spiralcoil, which are sandwiched and underlaid with magnetic thin films, are considered as the simulation models. The inductance increment of 300% compared to air-core inductor was predicted when the sandwiched 5μm thickness magnetic thin film with relative permeability of 600 was a...

  12. Curvature effects in thin magnetic shells.

    Science.gov (United States)

    Gaididei, Yuri; Kravchuk, Volodymyr P; Sheka, Denis D

    2014-06-27

    A magnetic energy functional is derived for an arbitrary curved thin shell on the assumption that the magnetostatic effects can be reduced to an effective easy-surface anisotropy; it can be used for solving both static and dynamic problems. General static solutions are obtained in the limit of a strong anisotropy of both signs (easy-surface and easy-normal cases). It is shown that the effect of the curvature can be treated as the appearance of an effective magnetic field, which is aligned along the surface normal for the case of easy-surface anisotropy and is tangential to the surface for the case of easy-normal anisotropy. In general, the existence of such a field excludes the solutions that are strictly tangential or strictly normal to the surface. As an example, we consider static equilibrium solutions for a cone surface magnetization.

  13. Growth induced magnetic anisotropy in crystalline and amorphous thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, F.

    1998-07-20

    The work in the past 6 months has involved three areas of magnetic thin films: (1) amorphous rare earth-transition metal alloys, (2) epitaxial Co-Pt and Ni-Pt alloy thin films, and (3) collaborative work on heat capacity measurements of magnetic thin films, including nanoparticles and CMR materials. A brief summary of work done in each area is given.

  14. Magnetic flux stabilizing thin accretion disks

    CERN Document Server

    Sadowski, Aleksander

    2016-01-01

    We calculate the minimal amount of large-scale poloidal magnetic field that has to thread the inner, radiation-over-gas pressure dominated region of a thin disk for its thermal stability. Such a net field amplifies the magnetization of the saturated turbulent state and makes it locally stable. For a $10 M_\\odot$ black hole the minimal magnetic flux is $10^{24}(\\dot M/\\dot M_{\\rm Edd})^{20/21}\\,\\rm G\\cdot cm^{2}$. This amount is compared with the amount of uniform magnetic flux that can be provided by the companion star -- estimated to be in the range $10^{22}-10^{24}\\,\\rm G\\cdot cm^2$. If accretion rate is large enough, the companion is not able to provide the required amount and such a system, if still sub-Eddington, must be thermally unstable. The peculiar variability of GRS 1915+105, an X-ray binary with the exceptionally high BH mass and near-Eddington luminosity, may result from the shortage of large scale poloidal field of uniform polarity.

  15. Magnetic flux stabilizing thin accretion discs

    Science.gov (United States)

    Sądowski, Aleksander

    2016-10-01

    We calculate the minimal amount of large-scale poloidal magnetic field that has to thread the inner, radiation-over-gas pressure dominated region of a thin disc for its thermal stability. Such a net field amplifies the magnetization of the saturated turbulent state and makes it locally stable. For a 10 M⊙ black hole the minimal magnetic flux is 10^{24}(dot{M}/dot{M}_Edd)^{20/21} G cm2. This amount is compared with the amount of uniform magnetic flux that can be provided by the companion star - estimated to be in the range 1022-1024 G cm2. If accretion rate is large enough, the companion is not able to provide the required amount and such a system, if still sub-Eddington, must be thermally unstable. The peculiar variability of GRS 1915+105, an X-ray binary with the exceptionally high BH mass and near-Eddington luminosity, may result from the shortage of large-scale poloidal field of uniform polarity.

  16. Determination of magnetic properties of multilayer metallic thin films

    CERN Document Server

    Birlikseven, C

    2000-01-01

    and magnetization measurements were taken. In recent year, Giant Magnetoresistance Effect has been attracting an increasingly high interest. High sensitivity magnetic field detectors and high sensitivity read heads of magnetic media can be named as important applications of these films. In this work, magnetic and electrical properties of single layer and thin films were investigated. Multilayer thin films were supplied by Prof. Dr. A. Riza Koeymen from Texas University. Multilayer magnetic thin films are used especially for magnetic reading and magnetic writing. storing of large amount of information into small areas become possible with this technology. Single layer films were prepared using the electron beam evaporation technique. For the exact determination of film thicknesses, a careful calibration of the thicknesses was made. Magnetic properties of the multilayer films were studied using the magnetization, magnetoresistance measurements and ferromagnetic resonance technique. Besides, by fitting the exper...

  17. Monte Carlo simulation of magnetic nanostructured thin films

    Institute of Scientific and Technical Information of China (English)

    Guan Zhi-Qiang; Yutaka Abe; Jiang Dong-Hua; Lin Hai; Yoshitake Yamazakia; Wu Chen-Xu

    2004-01-01

    @@ Using Monte Carlo simulation, we have compared the magnetic properties between nanostructured thin films and two-dimensional crystalline solids. The dependence of nanostructured properties on the interaction between particles that constitute the nanostructured thin films is also studied. The result shows that the parameters in the interaction potential have an important effect on the properties of nanostructured thin films at the transition temperatures.

  18. Magnetic Phases of Sputter Deposited Thin-Film Erbium

    Science.gov (United States)

    Witt, J. D. S.; Cooper, J. F. K.; Satchell, N.; Kinane, C. J.; Curran, P. J.; Bending, S. J.; Langridge, S.; Heyderman, L. J.; Burnell, G.

    2016-12-01

    We present a detailed structural and magnetic characterization of sputter deposited thin film erbium, determined by x-ray diffraction, transport measurements, magnetometry and neutron diffraction. This provides information on the onset and change of the magnetic state as a function of temperature and applied magnetic field. Many of the features of bulk material are reproduced. Also of interest is the identification of a conical magnetic state which repeats with a wavevector parallel to the c axis τc = 4/17 in units of the reciprocal lattice parameter c*, which is a state not observed in any other thin film or bulk measurements. The data from the various techniques are combined to construct magnetic field, temperature (H, T)–phase diagrams for the 200 nm-thick Er sample that serves as a foundation for future exploitation of this complex magnetic thin film system.

  19. Magnetic Surfaces, Thin Films, and Multilayers

    Science.gov (United States)

    1992-01-01

    PERPENDICULAR MAGNETIC ANISOTROPY AND MAGNETO-OPTICS * PERPENDICULAR MAGNETIC ANISOTROPY OF Pd/Co AND RELATED MULTILAYERS 441 S...THE PERPENDICULAR MAGNETIC ANISOTROPY AND STRUCTURE OF SPUTTERED Ag/Co, Pd/Co, AND AgPd/Co MULTILAYERED FILMS 473 Akira Yamaguchi, We-Hyo Soe, Ryoichi...the magnetic phase transi- tion and magnetic anisotropy, has attracted considerable interest. Theoretical predictions on perpendicular magnetic anisotropy

  20. Very simple torque magnetometer for measuring magnetic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tejedor, M.; Fernandez, A.; Hernando, B.; Carrizo, J.

    1985-11-01

    A new torque magnetometer has been developed and built in order to measure magnetization saturation and perpendicular anisotropy of magnetic thin films. Its main characteristic is that it employs for counteraction the torque exerted on the sample in the same field used for exciting it. This gives rise to a great simplicity and sensitivity of the measuring system.

  1. Impedance of a planar solenoid with a thin magnetic core

    NARCIS (Netherlands)

    Rejaei, B.; Vroubel, M.

    2007-01-01

    The high-frequency impedance of a planar solenoid with a thin magnetic core is theoretically investigated using the magnetostatic Green’s function formalism. It is shown that the electrical behavior of the solenoid depends on how the magnetic field induced by the current-carrying coil is coupled to

  2. HITPERM soft magnetic underlayers for perpendicular thin film media

    Science.gov (United States)

    Kumar, S.; Ohkubo, T.; Laughlin, D. E.

    2002-05-01

    In this work, a class of nanocrystalline alloys, HITPERM (Fe, Co)-M-B-Cu (M=Zr, Hf, Nb, and etc.) found to exhibit excellent soft-magnetic properties in bulk were used as soft-magnetic underlayers for perpendicular thin film media. A Ti intermediate layer was used to promote a (00ṡ2) texture and exchange de-couple the magnetic layer (CoCrPt) from the soft-magnetic underlayer. Specimens were deposited at both room and elevated temperature (˜ 250 °C). The results of x-ray diffraction and transmission electron microscope structural studies, along with magnetic properties are presented.

  3. Vanishing magnetic interactions in ferromagnetic thin films.

    Science.gov (United States)

    Dunn, J Hunter; Karis, O; Andersson, C; Arvanitis, D; Carr, R; Abrikosov, I A; Sanyal, B; Bergqvist, L; Eriksson, O

    2005-06-03

    We have used element-specific hysteresis measurements, based on the x-ray magnetic circular dichroism technique, to investigate magnetic trilayer structures composed of Fe and Ni layers. Within a critical regime we have discovered a class of structures in which the exchange interaction, the mechanism responsible for the macroscopic magnetism, can become vanishingly small. The experimental observations are supported by first principles theory and are explained as arising from a cancellation of several competing magnetic interactions. Hence, we have discovered a system with a novel exchange interaction between magnetic layers in direct contact that replaces the conventional exchange interaction in ferromagnets.

  4. Efficiency of Thin Magnetically-Arrested Disks Around Black Holes

    CERN Document Server

    Avara, Mark J; Reynolds, Chris S

    2015-01-01

    The radiative and jet efficiencies of thin magnetized accretion disks around black holes (BHs) are affected by BH spin and the presence of a magnetic field that, when strong, could lead to large deviations from Novikov-Thorne (NT) thin disk theory. To seek the maximum deviations, we perform general relativistic magnetohydrodynamic (GRMHD) simulations of radiatively efficient thin (half-height $H$ to radius $R$ of $H/R\\approx 0.10$) disks around moderately rotating BHs with $a/M=0.5$. First, our simulations, evolved for $108,000r_g/c$ (gravitational radius $r_g$ and speed of light $c$), show that large-scale magnetic field readily accretes inward even through our thin disk and builds-up to the magnetically-arrested disk (MAD) state. Second, our simulations of thin MADs show the disk achieves a radiative efficiency of $\\eta_{\\rm r}\\approx 15\\%$ (after estimating photon capture), which is about twice the NT value of $\\eta_{\\rm r}\\sim 8\\%$ for $a/M=0.5$ and gives the same luminosity as a NT disk with $a/M\\approx ...

  5. Competing magnetic anisotropies in obliquely deposited thin permalloy film

    Energy Technology Data Exchange (ETDEWEB)

    Belyaev, B.A. [Siberian Federal University, 79, pr. Svobodnyi, Krasnoyarsk 660041 (Russian Federation); Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, 50/38, Akademgorodok, Krasnoyarsk 660036 (Russian Federation); Reshetnev Siberian State Aerospace University, 31, pr. Imeni Gazety “Krasnoyarskii Rabochii”, Krasnoyarsk 660014 (Russian Federation); Izotov, A.V. [Siberian Federal University, 79, pr. Svobodnyi, Krasnoyarsk 660041 (Russian Federation); Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, 50/38, Akademgorodok, Krasnoyarsk 660036 (Russian Federation); Solovev, P.N., E-mail: platon.solovev@gmail.com [Siberian Federal University, 79, pr. Svobodnyi, Krasnoyarsk 660041 (Russian Federation)

    2016-01-15

    Distribution of the magnetic anisotropy in thin film prepared by thermal vacuum oblique deposition of permalloy with small off-normal angle of incident in the presence of an external magnetic field has been studied by ferromagnetic resonance technique. On local area of the sample, a mutual compensation of near orthogonal in-plane uniaxial magnetic anisotropies induced by oblique deposition and by applied magnetic field has been found. Moreover, in addition to the uniaxial (twofold) magnetic anisotropy, fourfold and sixfold magnetic anisotropies have been observed in the sample. To explain the obtained high-order anisotropies, we assumed that the sample has exchange coupled adjacent regions or phases with different parameters of magnetic anisotropy. The results of the micromagnetic analysis of a two-layer model of the sample confirm the hypothesis.

  6. Use split-flow approach to speed patients to needed care, eliminate inefficiencies and duplication.

    Science.gov (United States)

    2013-05-01

    To address time and space challenges in the midst of surging demand, the ED at St. Mary Medical Center in Langhorne, PA, turned to the split-flow model, an evidence-based practice that relies heavily on the queuing theory to improve patient throughput. In less than one year, the approach has enabled administrators to reduce door-to-physician times from an average of 47 minutes to 23.5 minutes, and overall length-of-stay in the ED for discharged patients has been slashed by 21 minutes. Under the split-flow system implemented at St. Mary, an expedited triage/assessment process directs patients to prompt care, pediatric care, acute care, or an expedited treatment area (ETA) where patients will undergo further testing or procedures. This initial assessment typically takes about three minutes. Patients sent to the ETA remain there for no longer than 30 minutes.They may then be moved to a holding area while awaiting test results. Patients are constantly moving in the split-flow model, so it is important to pay close attention to handoffs. Patients will begin the process with one nurse and finish with another.

  7. Magnetic properties of nanocrystalline FeNiN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, P.; Sanz, J.M. [Departamento de Fisica Aplicada and Instituto de Ciencia de Materiales ' ' Nicolas Cabrera' ' , Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Camarero, J.; Sacristan, N. [Departamento de Fisica de la Materia Condensada and Instituto de Ciencia de Materiales ' ' Nicolas Cabrera' ' , Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Boerma, D.O. [Departamento de Fisica de la Materia Condensada and Centro de Micro Analisis de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2006-05-15

    FeNiN thin films with a Ni content varying between 5 and 36 at% (as determined by X-ray photoelectron spectroscopy) have been deposited in a Dual Ion Beam Sputtering System at room temperature. The structure and crystalline size were studied by X-ray diffraction while the magnetic properties were investigated by vectorial kerr magnetometry. In general, the deposited films present a nanocrystaline cubic structure and well defined in-plane magnetic anisotropy. The variation of the magnetic properties was attributed to changes in composition and nanocrystalline structure. FeNiN thin films with a Ni content of about 15 at% show the better soft magnetic properties with a minimum in the coercivity of 9 Oe. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Micromagnetism and magnetization reversal of micron-scale (110) Fe thin-film magnetic elements

    OpenAIRE

    Yu, Jun; Rüdiger, Ulrich; Kent, Andrew D.; Thomas, Luc; Parkin, Stuart S. P.

    1999-01-01

    Magnetic force microscope (MFM) imaging in conjunction with longitudinal Kerr hysteresis loop measurements have been used to investigate the micromagnetic behavior of micron scale epitaxial (110) bcc Fe thin-film elements (50-nm thick) with rectangular, triangular, and needle-shaped ends and competing magnetic anisotropies. Thin-film elements of 2-mm width and 6-mm length and greater have been fabricated with their long axis oriented either parallel or perpendicular to the [001] in-plane magn...

  9. Magnetic properties on strained manganite thin film

    Science.gov (United States)

    Prajapat, C. L.; Singh, M. R.; Gupta, S. K.; Bhattacharya, D.; Basu, S.; Ravikumar, G.

    2014-04-01

    Structural and magnetic studies on La2/3Sr1/3MnO3 (LSMO) epitaxial films grown on STO (100) and MgO (100) substrates by Pulsed Laser Deposition are presented. Due to larger interface strain, the grain size of LSMO on MgO is much smaller than that on STO substrate. However, anisotropy energy produced as a result of in plane tensile strain is much larger in case of the films deposited on MgO in such a way that the blocking (irreversibility) temperature and the coercive fields inferred from temperature and magnetic field dependent magnetization measurements are significantly higher. The importance of this result for the memory applications is highlighted.

  10. Left-handed materials in magnetized metallic magnetic thin films

    Institute of Scientific and Technical Information of China (English)

    WU Rui-xin; XIAO John Q.

    2006-01-01

    The authors' theoretical investigation on the high-frequency response of magnetized metallic magnetic films showed that magnetic films may become left-handed materials (LHMs) near the ferromagnetic resonance frequency of incident waves with right-handed circular polarization (RCP) and linear polarization (LP). The frequency range where LHM exists depends on the waves polarization, the magnetic damping coefficient, and the ferromagnetic characteristic frequency ωm of the film. There also exists a critical damping coefficient αc, above which the left-handed properties disappear completely.

  11. Reorientation of magnetic anisotropy in obliquely sputtered metallic thin films

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.; Wormeester, H.; Poelsema, B.

    2002-01-01

    Reorientation in the magnetic anisotropy as a function of film thickness has been observed in Co-Ni and Co thin films, obliquely sputtered on a polyethylene terephthalate substrate at a large incidence angle (70°). This effect is a consequence of the low magnetocrystalline anisotropy of the films (f

  12. Magnetic properties of electrodeposited Co-W thin films

    NARCIS (Netherlands)

    Admon, U.; Dariel, M.P.; Grunbaum, E.; Lodder, J.C.

    1987-01-01

    Thin films of Co-W, 300-500 Å thick, were electrodeposited at various compositions under a wide range of plating conditions. The saturation magnetization, coercivity, and squareness ratio of the films were derived from the parallel (in-plane) and perpendicular hysteresis loops, measured by using a v

  13. Quantum-well-driven magnetism in thin films

    DEFF Research Database (Denmark)

    Mirbt, S.; Johansson, B.; Skriver, Hans Lomholt

    1996-01-01

    We have performed local spin-density calculations for an fee (100) Ag substrate covered by 1 to 16 monolayers (ML) of Pd. We find that thin films of Pd are magnetic with a moment of the order of 0.3 mu(B) except for films of 1-2 ML and 5-7 ML where magnetism is completely suppressed. We present...... a physically transparent explanation of this behavior in terms of the Stoner picture and magnetic quantum-well states....

  14. The spin-wave spectrum of layered magnetic thin films

    Science.gov (United States)

    van Stapele, R. P.; Greidanus, F. J. A. M.; Smits, J. W.

    1985-02-01

    The ferromagnetic resonance spectrum of a layered magnetic thin film is expected to show a number of standing spin-wave resonances with a wavelength that matches the thickness of the film. For the case of perpendicular resonance such spectra were calculated for some typical films in which magnetic layers are alternated with weaker magnetic layers. Some useful approximations are discussed. The results of the calculations are compared with experimental perpendicular spectra measured on films in which fifty Permalloy layers alternate with Ni layers.

  15. Preparation and magnetic properties of Co-P thin films

    Institute of Scientific and Technical Information of China (English)

    Haicheng Wang; Zhongmei Du; Lijin Wang; Guanghua Yu; Fengwu Zhu

    2008-01-01

    Magnetic Co-P thin films were prepared by eleetroless deposition. The experiment results show that the film thickness has a significant influence on the coercivity. While the film thickness varied from 300 nm to 5 μm, the coercivity dropped sharply from 45.36 to 22.28 kA/m. As the film thickness increased further, the coercivity varied slowly. When the thickness of the film was 300 nm, the deposited film could realize the coercivity as high as 45.36 kA/m, and the remanent magnetization as high as 800 kA/m .The Co-P films were deposited on the surface of magnetic drums of encoders, whose diameter was 40 mm, and then 512 magnetic poles were recorded, meaning that the magnetizing pitch was 0.245 mm. The testing results indicate that the output signals are perfect, the output waveforms are steady and the pulses account is integral. Compared with the γ-Fe2O3 coating, the Co-P thin film is suitable to be the magnetic recording media for the high resolution magnetic rotary encoder.

  16. Magnetic properties of a long, thin-walled ferromagnetic nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Chen, E-mail: chen.sun@physics.tamu.edu [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Pokrovsky, Valery L. [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Landau Institute for Theoretical Physics, Chernogolovka, Moscow District, 142432 (Russian Federation)

    2014-04-15

    We consider magnetic properties of a long, thin-walled ferromagnetic nanotube. We assume that the tube consists of isotropic homogeneous magnet whose spins interact via the exchange energy, the dipole–dipole interaction energy, and also interact with an external field via Zeeman energy. Possible stable states are the parallel state with the magnetization along the axis of the tube, and the vortex state with the magnetization along azimuthal direction. For a given material, which of them has lower energy depends on the value γ=R{sup 2}d/(Lλ{sub x}{sup 2}), where R is the radius of the tube, d is its thickness, L is its length and λ{sub x} is an intrinsic scale of length characterizing the ratio of exchange and dipolar interaction. At γ<1, the parallel state wins, otherwise the vortex state is stable. A domain wall in the middle of the tube is always energy unfavorable, but it can exist as a metastable structure. Near the ends of a tube magnetized parallel to the axis a half-domain structure transforming gradually the parallel magnetization to a vortex just at the edge of the tube is energy favorable. We also consider the equilibrium magnetization textures in an external magnetic field either parallel or perpendicular to the tube. Finally, magnetic field produced by a nanotube and an array of tubes is analyzed. - Highlights: • We obtain a simple criterion for stable state of a long, thin-walled magnetic tube. • A domain wall in the middle is always energy unfavorable, but can be metastable. • In external field different states show different hystereses. • Field produced by a tube and an array of tubes is calculated.

  17. Efficiency of thin magnetically arrested discs around black holes

    Science.gov (United States)

    Avara, Mark J.; McKinney, Jonathan C.; Reynolds, Christopher S.

    2016-10-01

    The radiative and jet efficiencies of thin magnetized accretion discs around black holes (BHs) are affected by BH spin and the presence of a magnetic field that, when strong, could lead to large deviations from Novikov-Thorne (NT) thin disc theory. To seek the maximum deviations, we perform general relativistic magnetohydrodynamic simulations of radiatively efficient thin (half-height H to radius R of H/R ≈ 0.10) discs around moderately rotating BHs with a/M = 0.5. First, our simulations, each evolved for more than 70 000 rg/c (gravitational radius rg and speed of light c), show that large-scale magnetic field readily accretes inward even through our thin disc and builds-up to the magnetically arrested disc (MAD) state. Secondly, our simulations of thin MADs show the disc achieves a radiative efficiency of ηr ≈ 15 per cent (after estimating photon capture), which is about twice the NT value of ηr ˜ 8 per cent for a/M = 0.5 and gives the same luminosity as an NT disc with a/M ≈ 0.9. Compared to prior simulations with ≲10 per cent deviations, our result of an ≈80 per cent deviation sets a new benchmark. Building on prior work, we are now able to complete an important scaling law which suggests that observed jet quenching in the high-soft state in BH X-ray binaries is consistent with an ever-present MAD state with a weak yet sustained jet.

  18. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Surbhi [Department of Physics and Astrophysics, University of Delhi (India); Tomar, Monika [Physics Department, Miranda House, University of Delhi (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi (India)

    2015-03-15

    The influence of Cerium doping on the structural and magnetic properties of BiFeO{sub 3} thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi{sub 1−x}Ce{sub x}FeO{sub 3} (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm{sup −1}) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm{sup −1}), shows a minor shift. Sudden evolution of Raman mode at 668 cm{sup −1}, manifested as A{sub 1}-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (M{sub s}) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi{sub 0.88}Ce{sub 0.12}FeO{sub 3} thin film found to exhibit better magnetic properties with M{sub s}=15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi{sub 1−x}Ce{sub x}FeO{sub 3} thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical

  19. Competing magnetic interactions in quantum thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bueno, M.J. [Departamento de Física, CCEN, Universidade Federal da Paraíba, Cidade Universitária, 58051-970 João Pessoa, PB (Brazil); Faria, Jorge L.B. [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900 Cuiabá, MT (Brazil); Arruda, Alberto S. de, E-mail: aarruda@fisica.ufmt.br [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900 Cuiabá, MT (Brazil); Craco, L. [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900 Cuiabá, MT (Brazil); Sousa, J. Ricardo de, E-mail: jsousa@ufam.edu.br [Departamento de Física, Universidade Federal do Amazonas, 69077-000 Manaus, AM (Brazil)

    2013-07-15

    In this work we study the quantum spin-1/2 Heisenberg model in two dimensions, with a nearest-neighbor short-range antiferromagnetic exchange (J) and a long-range ferromagnetic dipole–dipole (E{sub d}) coupling. Using the double-time Green's function method within the random phase approximation (RPA) we obtain the magnon dispersion relation as function of frustration parameter δ (δ being the ratio between exchange and dipolar interactions δ=J/E{sub d}). We study the competition between long-range ferromagnetic dipole–dipole interaction and short-range antiferromagnetic exchange in stabilizing the magnetic long-range order in a two-dimensional system. We find that the ferromagnetic order is stable at small k up to critical value of frustration δ{sub c}=0.04375. For frustration higher than the critical value (δ>δ{sub c}) our magnetic system is disordered. - Highlights: ► Competition between interactions short-range (exchange J) and long-range dipole–dipole (E{sub d}) is studied. ► The quantum spin-1/2 Heisenberg model in two dimensions is used as example. ► The interactions are exchange (antiferromagnetic) and ferromagnetic dipole–dipole. ► The double-time Green's function method and RPA is used to obtain the dispersion relations of the acoustic branch. ► The system has ferromagnetic order stable for values less than critical of frustration (J/E{sub d})

  20. Preparation and magnetization reversal of exchange bias structured thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, Christine; McCord, Jeffrey; Moench, Ingolf; Kaltofen, Rainer; Gemming, Thomas; Schaefer, Rudolf; Schultz, Ludwig [Leibniz Institute for Solid State and Materials Research, Dresden (Germany)

    2008-07-01

    Magnetically patterned thin films of NiFe/IrMn/Ta-NiFe/IrMnO{sub x} with laterally modulated unidirectional anisotropy were prepared by local oxidation of the antiferromagnetic IrMn layer. Varying the lateral dimensions and orientation with respect to the anisotropy modulation, the films exhibit different magnetization reversal behaviors. While stripes aligned parallel to the unidirectional anisotropy direction display a spin valve-like two step hysteresis loop, perpendicular orientation lead to a single step shifted hysteresis loop. Magnetic domain observation reveals separate switching of the stripes for the parallel alignment and simultaneous reversal for the perpendicular orientation. By decreasing the lateral dimensions, quasi-domain states have been observed. The presented magnetic data of the exchange biased-patterned films show that we did succeed in creating an alternative method for the preparation of materials with new hybrid properties.

  1. Quantum transport in magnetic topological insulator thin films.

    Science.gov (United States)

    Lu, Hai-Zhou; Zhao, An; Shen, Shun-Qing

    2013-10-04

    The experimental observation of the long-sought quantum anomalous Hall effect was recently reported in magnetically doped topological insulator thin films [Chang et al., Science 340, 167 (2013)]. An intriguing observation is a rapid decrease from the quantized plateau in the Hall conductance, accompanied by a peak in the longitudinal conductance as a function of the gate voltage. Here, we present a quantum transport theory with an effective model for magnetic topological insulator thin films. The good agreement between theory and experiment reveals that the measured transport originates from a topologically nontrivial conduction band which, near its band edge, has concentrated Berry curvature and a local maximum in group velocity. The indispensable roles of the broken structure inversion and particle-hole symmetries are also revealed. The results are instructive for future experiments and transport studies based on first-principles calculations.

  2. Finite element analysis of magnetization reversal in granular thin films

    CERN Document Server

    Spargo, A W

    2002-01-01

    This thesis develops a Galerkin finite element model of magnetisation dynamics in granular thin films. The governing equations of motion are the Gilbert equations with an effective magnetic field taking contributions from exchange interactions, magnetocrystalline anisotropy, applied magnetic field as well as the magnetostatic field given by Maxwells equations. The magnetostatic field is formulated as a scalar potential described by Poissons equation which is solved using a second order finite element method. The Gilbert equations are discretized in time using an implicit midpoint method which naturally conserves the magnitude of the magnetisation vector. An infinite thin film is approximated using periodic boundary conditions with material microstructure represented using the Voronoi tessellation. The effects of thermal fluctuations are modelled by the stochastic Langevin-Gilbert equations, again solved by a Galerkin finite element method. The implicit midpoint time-stepping scheme ensures that solutions conv...

  3. Electrodeposition of magnetic thin films of cobalt on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Munford, M.L.; Seligman, L.; Sartorelli, M.L.; Voltolini, E.; Martins, L.F.O.; Schwarzacher, W.; Pasa, A.A. E-mail: pasa@fisica.ufsc.br

    2001-05-01

    To understand the electrodeposition of Co on Si, sulphate electrolytes containing two different Co ion concentrations were tested. Thin films with uniform thickness, ranging from 10 to 700 nm, low surface roughness, compact and metallic appearance were obtained for Co concentrations of 26 and 104 mM, respectively. Transverse MOKE measurements showed in-plane magnetization with the magnitude of the coercive field being dependent on the thickness of the deposited layers. VSM measurements with the applied field perpendicular to the surface allowed the observation of an out-of-plane remanent magnetization. These properties are of considerable interest for technological applications.

  4. Second Harmonic Generation from Co Magnetic Thin Films

    Institute of Scientific and Technical Information of China (English)

    卢永雄; 叶骏; 金庆原

    2003-01-01

    The magnetization-induced second harmonic generation (MSHG) in the sputtered and epitaxial-grown Co thin films was studied. The magnetic contrast of the MSHG intensity could be clearly distinguished for the cobalt films prepared by both the methods, but the signal measured in air for sputtered films was not smoother than that for the in-situ measurement of epitaxial films. Compared with the magneto-optical Kerr effect, the MSHG shows some new behaviour indicating that more information could be obtained if these two methods are combined. The MSHG reveals a giant nonlinear Kerr rotation in orders of magnitude larger than its linear one.

  5. Surface studies of magnetic thin films

    CERN Document Server

    Zeybek, O

    2000-01-01

    Despite the resonances of the various multiplet components the dichroism signal retains a uniform spectral shape. The well-resolved multiplet structures have been obtained in 5p photoemission of Tb using circularly polarised light. This multiplet structure is caused by the interaction between the core level photohole and those partially filled subshell, i.e. as result of the unpaired 4f and 5p electrons. In 4f levels of Tb(0001) films, the well-resolved surface component of the Tb sup 8 S sub 7 sub / sub 2 has been observed a separation of magnetic circular dichroism in the angular dependence effect for the surface layer and for the bulk. Depending on the preparation procedure, new iron superstructures on W(110) substrate have been observed. The photographs of the LEED images provide information about the ordered arrangement of atoms on the surface and the distances between the spots. These LEED patterns are also an evidence of crystal structure of iron films. The sharpness of the spots gives insight on how w...

  6. Magnetic coupling mechanisms in particle/thin film composite systems

    Directory of Open Access Journals (Sweden)

    Giovanni A. Badini Confalonieri

    2010-12-01

    Full Text Available Magnetic γ-Fe2O3 nanoparticles with a mean diameter of 20 nm and size distribution of 7% were chemically synthesized and spin-coated on top of a Si-substrate. As a result, the particles self-assembled into a monolayer with hexagonal close-packed order. Subsequently, the nanoparticle array was coated with a Co layer of 20 nm thickness. The magnetic properties of this composite nanoparticle/thin film system were investigated by magnetometry and related to high-resolution transmission electron microscopy studies. Herein three systems were compared: i.e. a reference sample with only the particle monolayer, a composite system where the particle array was ion-milled prior to the deposition of a thin Co film on top, and a similar composite system but without ion-milling. The nanoparticle array showed a collective super-spin behavior due to dipolar interparticle coupling. In the composite system, we observed a decoupling into two nanoparticle subsystems. In the ion-milled system, the nanoparticle layer served as a magnetic flux guide as observed by magnetic force microscopy. Moreover, an exchange bias effect was found, which is likely to be due to oxygen exchange between the iron oxide and the Co layer, and thus forming of an antiferromagnetic CoO layer at the γ-Fe2O3/Co interface.

  7. Computational and experimental investigations of magnetic domain structures in patterned magnetic thin films

    Science.gov (United States)

    Li, Yulan; Xu, Ke; Hu, Shenyang; Suter, Jon; Schreiber, Daniel K.; Ramuhalli, Pradeep; Johnson, Bradley R.; McCloy, John

    2015-08-01

    The use of nondestructive magnetic signatures for continuous monitoring of the degradation of structural materials in nuclear reactors is a promising yet challenging application for advanced functional materials behavior modeling and measurement. In this work, a numerical model, which is based on the Landau-Lifshitz-Gilbert equation of magnetization dynamics and the phase field approach, was developed to study the impact of defects such as nonmagnetic precipitates and/or voids, free surfaces and crystal orientation on magnetic domain structures and magnetic responses in magnetic materials, with the goal of exploring the correlation between microstructures and magnetic signatures. To validate the model, single crystal iron thin films (~240 nm thickness) were grown on MgO substrates and a focused ion beam was used to pattern micrometer-scale specimens with different geometries. Magnetic force microscopy (MFM) was used to measure magnetic domain structure and its field-dependence. Numerical simulations were constructed with the same geometry as the patterned specimens and under similar applied magnetic field conditions as tested by MFM. The results from simulations and experiments show that 1) magnetic domain structures strongly depend on the film geometry and the external applied field and 2) the predicted magnetic domain structures from the simulations agree quantitatively with those measured by MFM. The results demonstrate the capability of the developed model, used together with key experiments, for improving the understanding of the signal physics in magnetic sensing, thereby providing guidance to the development of advanced nondestructive magnetic techniques.

  8. Piezoelectric response of a PZT thin film to magnetic fields from permanent magnet and coil combination

    Science.gov (United States)

    Guiffard, B.; Seveno, R.

    2015-01-01

    In this study, we report the magnetically induced electric field E 3 in Pb(Zr0.57Ti0.43)O3 (PZT) thin films, when they are subjected to both dynamic magnetic induction (magnitude B ac at 45 kHz) and static magnetic induction ( B dc) generated by a coil and a single permanent magnet, respectively. It is found that highest sensitivity to B dc——is achieved for the thin film with largest effective electrode. This magnetoelectric (ME) effect is interpreted in terms of coupling between eddy current-induced Lorentz forces (stress) in the electrodes of PZT and piezoelectricity. Such coupling was evidenced by convenient modelling of experimental variations of electric field magnitude with both B ac and B dc induction magnitudes, providing imperfect open circuit condition was considered. Phase angle of E 3 versus B dc could also be modelled. At last, the results show that similar to multilayered piezoelectric-magnetostrictive composite film, a PZT thin film made with a simple manufacturing process can behave as a static or dynamic magnetic field sensor. In this latter case, a large ME voltage coefficient of under B dc = 0.3 T was found. All these results may provide promising low-cost magnetic energy harvesting applications with microsized systems.

  9. Magnetic and structural investigation of magnetic thin films with obliquely deposited underlayers

    CERN Document Server

    Hadley, M J

    2002-01-01

    An in-plane uniaxial magnetic anisotropy has been observed in thin Co films normally deposited onto obliquely sputtered Ta and Pt underlayers. Associated with this anisotropy is an augmented easy axis coercivity. The in-plane easy axis is, in most cases, perpendicular to the incident deposition plane. Microstructural results indicate that grains are well connected along the magnetic easy axis but are separated by long continuous voids along the hard axis, which is ascribed to a geometric shadowing effect due to the oblique incidence deposition of the underlayer. Hence, the magnetic anisotropy mimics the film growth anisotropy. It is therefore believed that the observed magnetic properties are due to magnetostatic shape anisotropy effects. In-plane coercivity and anisotropy field are shown to increase with underlayer deposition angle, underlayer thickness and magnetic layer thickness. The choice of capping layer is also observed to dramatically alter the magnetics, as did the sample temperature. In general, Pt...

  10. Magnetic Behavior of Surface Nanostructured 50-nm Nickel Thin Films

    Directory of Open Access Journals (Sweden)

    Kumar Prashant

    2010-01-01

    Full Text Available Abstract Thermally evaporated 50-nm nickel thin films coated on borosilicate glass substrates were nanostructured by excimer laser (0.5 J/cm2, single shot, DC electric field (up to 2 kV/cm and trench-template assisted technique. Nanoparticle arrays (anisotropic growth features have been observed to form in the direction of electric field for DC electric field treatment case and ruptured thin film (isotropic growth features growth for excimer laser treatment case. For trench-template assisted technique; nanowires (70–150 nm diameters have grown along the length of trench template. Coercive field and saturation magnetization are observed to be strongly dependent on nanostructuring techniques.

  11. Thin accretion discs are stabilized by a strong magnetic field

    Science.gov (United States)

    Sądowski, Aleksander

    2016-07-01

    By studying three-dimensional, radiative, global simulations of sub-Eddington, geometrically thin (H/R ≈ 0.15) black hole accretion flows we show that thin discs which are dominated by magnetic pressure are stable against thermal instability. Such discs are thicker than predicted by the standard model and show significant amount of dissipation inside the marginally stable orbit. Radiation released in this region, however, does not escape to infinity but is advected into the black hole. We find that the resulting accretion efficiency (5.5 ± 0.5 per cent for the simulated 0.8dot{M}_Edd disc) is very close to the predicted by the standard model (5.7 per cent).

  12. Field orientation dependence of magnetization reversal in thin films with perpendicular magnetic anisotropy

    Science.gov (United States)

    Fallarino, Lorenzo; Hovorka, Ondrej; Berger, Andreas

    2016-08-01

    The magnetization reversal process of hexagonal-close-packed (hcp) (0001) oriented Co and C o90R u10 thin films with perpendicular magnetic anisotropy (PMA) has been studied as a function of temperature and applied magnetic field angle. Room temperature pure cobalt exhibits two characteristic reversal mechanisms. For angles near in-plane field orientation, the magnetization reversal proceeds via instability of the uniform magnetic state, whereas in the vicinity of the out-of-plane (OP) orientation, magnetization inversion takes place by means of domain nucleation. Temperature dependent measurements enable the modification of the magnetocrystalline anisotropy and reveal a gradual disappearance of the domain nucleation process during magnetization reversal for elevated temperatures. Ultimately, this suppression of the domain nucleation process leads to the exclusive occurrence of uniform state instability reversal for all field orientations at sufficiently high temperature. Comparative magnetic measurements of C o90R u10 alloy samples allow the identification and confirmation of the high temperature remanent magnetization state of cobalt as an OP stripe domain state despite the reduction of magnetocrystalline anisotropy. Detailed micromagnetic simulations supplement the experimental results and corroborate the physical understanding of the temperature dependent behavior. Moreover, they enable a comprehensive identification of the complex energy balance in magnetic films with PMA, for which three different magnetic phases occur for sufficiently high anisotropy values, whose coexistence point is tricritical in nature.

  13. Local imaging of magnetic flux in superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shapoval, Tetyana

    2010-01-26

    Local studies of magnetic flux line (vortex) distribution in superconducting thin films and their pinning by natural and artificial defects have been performed using low-temperature magnetic force microscopy (LT-MFM). Taken a 100 nm thin NbN film as an example, the depinning of vortices from natural defects under the influence of the force that the MFM tip exerts on the individual vortex was visualized and the local pinning force was estimated. The good agreement of these results with global transport measurements demonstrates that MFM is a powerful and reliable method to probe the local variation of the pinning landscape. Furthermore, it was demonstrated that the presence of an ordered array of 1-{mu}m-sized ferromagnetic permalloy dots being in a magneticvortex state underneath the Nb film significantly influences the natural pinning landscape of the superconductor leading to commensurate pinning effects. This strong pinning exceeds the repulsive interaction between the superconducting vortices and allows vortex clusters to be located at each dot. Additionally, for industrially applicable YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films the main question discussed was the possibility of a direct correlation between vortices and artificial defects as well as vortex imaging on rough as-prepared thin films. Since the surface roughness (droplets, precipitates) causes a severe problem to the scanning MFM tip, a nanoscale wedge polishing technique that allows to overcome this problem was developed. Mounting the sample under a defined small angle results in a smooth surface and a monotonic thickness reduction of the film along the length of the sample. It provides a continuous insight from the film surface down to the substrate with surface sensitive scanning techniques. (orig.)

  14. Dual spiral sandwiched magnetic thin film inductor using Fe-Hf-N soft magnetic films as a magnetic core

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.H.; Yoo, D.W.; Jeong, J.H.; Kim, J.; Han, S.H. E-mail: sukhan@kist.re.kr; Kim, H.J

    2002-02-01

    Dual spiral sandwiched magnetic thin film inductors are fabricated using as-deposited Fe-Hf-N soft magnetic thin films. The hard axis of the magnetic film is aligned transverse to the direction of coil conductor current, which is expected to result in high inductance values as well as excellent frequency response. The inductance, Q factor and resistance are measured using impedance analyzer from 1 to 10 MHz. The inductance of fabricated thin film inductors are obtained within the range of 1.1-1.5 {mu}H. Also, the quality factor and coil resistance is obtained in the range of 3-38 at 8 MHz and 1-2.5 {omega}, respectively.

  15. Novel metal-carbon(60) nanocrystalline magnetic thin films

    Science.gov (United States)

    Zheng, Lingyi

    1999-11-01

    A novel type of nanocrystalline magnetic thin films consisting of ferromagnetic metals and C60 have been developed and investigated. CO-C 60, Fe-C60 and CoFe-C60 with different concentrations of C60 thin films have been manufactured by thermal vapor codeposition. The microstructures and magnetic properties of the films can be significantly enhanced by varying the concentrations of C60 in the films. The stability of C60 and the compatibility of C60 with the metallic matrices are confirmed by mass spectrometry, Raman, WDS, XRD and TEM. Strong metal- C60 interaction is indicated by higher desorption temperatures of C60 in the meta- C60 films than that in pure C60 and the peak shift in Raman spectra. TEM shows that the grain size of the matrix metal decreases proportionally with increasing C60 concentration. Nanosize uniform columnar grains with nanoscale dispersion of C60 on the grain boundaries are commonly observed in the metal-C60 films. A self- assembly grain growth model based on the size effect of C60 and the metal-C60 interaction is proposed to delineate the microstructural evolution by C60. Calculations based on this model are consistent with experimental observations and give a grain size vs. C60 (carbon) concentration relationship. Grain growth retardation by C60 is observed in a CO-C60 film. Out-plane magnetic remanence and coercivity are enhanced in both the CO-C60 and Fe-C60 films. In the in-plane direction, the coercivity deceases in CO- C60 films but increases slightly in Fe- C60 films with increasing C60 concentrations. In-plane magnetic anisotropy is detected in CO-C60 films but not in Fe-C60 films. Strong temperature-dependent magnetization remanence and saturation are found in both the Co- C60 and Fe-C60 films with high C60 concentrations due to the nanosize grain effects. Temperature effects on the coercivity of CO- C60 and Fe-C60 are different and determined by the intrinsic magnetocrystalline anisotropy energy. Coercivity of the CoFe-C60 films

  16. Microscopic thin shell wormholes in magnetic Melvin universe

    CERN Document Server

    Mazharimousavi, S Habib; Amirabi, Z

    2014-01-01

    We construct thin shell wormholes in the magnetic Melvin universe. It is shown that in order to make a TSW in the Melvin spacetime the radius of the throat can not be larger than $\\frac{2}{B_{0}}$ in which $B_{0}$ is the magnetic field constant. We also analyze the stability of the constructed wormhole in terms of a linear perturbation around the equilibrium point. In our stability analysis we scan a full set of the Equation of States such as Linear Gas, Chaplygin Gas, Generalized Chaplygin Gas, Modified Generalized Chaplygin Gas and Logarithmic Gas. Finally we extend our study to the wormhole solution in the unified Melvin and Bertotti-Robinson spacetime. In this extension we show that for some specific cases, the local energy density is partially positive but the total energy which supports the wormhole is positive.

  17. Magnetic degradation of thin film multilayers during ion milling

    Directory of Open Access Journals (Sweden)

    J. C. Read

    2014-04-01

    Full Text Available We present a study of Ar ion milling-induced damage in exchange biased IrMn/CoFe/Ag-based magnetic multilayer thin films. While process variations determine the change in CoFe magnetic properties, the distance from the ion milling front to the IrMn/CoFe interface dominates the extent of exchange bias damage. Remarkably, the interfacial coupling energy Jk can be reduced by 50% before any removal of the CoFe pinned layer. We attribute the losses to microstructural changes and damage effects where cap material is driven into the CoFe layer below. Disturbance depth estimates from ion impact simulations agree reasonably with the observed length scales of damage.

  18. Static and dynamic critical behavior of thin magnetic Ising films

    Science.gov (United States)

    Sabogal-Suárez, D.; Alzate-Cardona, J. D.; Restrepo-Parra, E.

    2015-09-01

    This work presents a study of the effect of film thickness on the static and dynamic critical behavior of thin magnetic Ising films. Monte Carlo simulations using the Wolff algorithm were performed to determine the static and dynamic critical exponents of the films. A dimensionality crossover from 2D to 3D (due to the finiteness of the films) in the static and dynamic critical behavior was observed as the film thickness increases. In addition, a slight increase in the effective dimension deff and a considerable increase in the critical temperature Tc(∞) were found. Small values for the dynamic critical exponents were obtained, indicating that the Wolff algorithm is a very efficient method for these magnetic systems.

  19. Microscopic thin-shell wormholes in magnetic Melvin universe

    Energy Technology Data Exchange (ETDEWEB)

    Mazharimousavi, S.H.; Halilsoy, M.; Amirabi, Z. [Eastern Mediterranean University, Department of Physics, North Cyprus, Mersin 10 (Turkey)

    2014-05-15

    We construct thin-shell wormholes in the magnetic Melvin universe. It is shown that in order to make a TSW in the Melvin spacetime the radius of the throat cannot be larger than (2)/(B{sub 0}), in which B{sub 0} is the magnetic field constant. We also analyze the stability of the constructed wormhole in terms of a linear perturbation around the equilibrium point. In our stability analysis we scan a full set of the Equation of States such as Linear Gas, Chaplygin Gas, Generalized Chaplygin Gas, Modified Generalized Chaplygin Gas, and Logarithmic Gas. Finally we extend our study to the wormhole solution in the unified Melvin and Bertotti-Robinson spacetime. In this extension we show that for some specific cases, the local energy density is partially positive but the total energy which supports the wormhole is positive. (orig.)

  20. Thermal Stability of Magnetic States in Circular Thin-Film Nanomagnets with Large Perpendicular Magnetic Anisotropy

    Science.gov (United States)

    Chaves-O'Flynn, Gabriel

    The scaling of the energy barrier to magnetization reversal in thin-film nanomagnets with perpendicular magnetization as a function of their lateral size is of great interest and importance for high-density magnetic random access memory devices. Experimental studies of such elements show either a quadratic or linear dependence of the energy barrier on element diameter. I will discuss a theoretical model we developed to determine the micromagnetic configurations that set the energy barrier for thermally activated reversal of a thin disk with perpendicular magnetic anisotropy as a function of disk diameter. We find a critical length in the problem that is set by the exchange and effective perpendicular magnetic anisotropy energies, with the latter including the size dependence of the demagnetization energy. For diameters smaller than this critical length, the reversal occurs by nearly coherent magnetization rotation and the energy barrier scales with the square of the diameter normalized to the critical length (for fixed film thickness), while for larger diameters, the transition state has a domain wall, and the energy barrier depends linearly on the normalized diameter. Simple analytic expressions are derived for these two limiting cases and verified using full micromagnetic simulations with the string method. Further, the effect of an applied field is considered and shown to lead to a plateau in the energy barrier versus diameter dependence at large diameters. Based on these finding I discuss the prospects and material challenges in the scaling of magnetic memory devices based on thin films with strong perpendicular magnetic anisotropy. In collaboration with G. Wolf, J. Z. Sun and A. D. Kent. Supported by NSF-DMR-1309202 and in part by Spin Transfer Technologies Inc. and the Nanoelectronics Research Initiative through the Institute for Nanoelectronics Discovery and Exploration.

  1. CoCrTa thin films for magnetic recording media: structure, magnetic properties and time-dependence effect

    NARCIS (Netherlands)

    Phan le kim, P.L.K.

    This thesis has been devoted to deposition process, structures, magnetic properties and time-dependence effect of CoCrTa magnetic thin films for recording media. The experimental study began from Chapter 5 by investigating properties of single layer CoCrTa thin films, produced under different

  2. Magnetic properties of electrodeposited Co-W thin films

    Energy Technology Data Exchange (ETDEWEB)

    Admon, U.; Dariel, M.P.; Grunbaum, E.; Lodder, J.C.

    1987-09-01

    Thin films of Co-W, 300--500 A thick, were electrodeposited at various compositions under a wide range of plating conditions. The saturation magnetization, coercivity, and squareness ratio of the films were derived from the parallel (in-plane) and perpendicular hysteresis loops, measured by using a vibrating sample magnetometer. The magnetic properties of the films are strongly related to their microstructure. The nonmagnetic alloying element (W) affects the saturation magnetization via the dilution mechanism. The in-plane coercivity, which increases with increasing content of the hexagonal phase and with decreasing degree of (0001)h texture, is in the range of 100--600 Oe for the crystalline deposits and decreases to a few oersteds for amorphous deposits. The in-plane squareness ratio increases with the fcc or amorphous phase content and with decreasing degree of (0001)h texture. The magnetic measurements suggest that films that appeared amorphous according to their electron diffraction patterns are actually microcrystalline or at least partially crystallized.

  3. High magnetic field properties of Fe-pnictide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, Fritz

    2015-11-20

    The recent discovery of high-temperature superconductivity in Fe-based materials triggered worldwide efforts to investigate their fundamental properties. Despite a lot of similarities to cuprates and MgB{sub 2}, important differences like near isotropic behaviour in contrast to cuprates and the peculiar pairing symmetry of the order parameter (OP) have been reported. The OP symmetry of Fe-based superconductors (FBS) was theoretically predicted to be of so-called s± state prior to various experimental works. Still, most of the experimental results favour the s± scenario; however, definitive evidence has not yet been reported. Although no clear understanding of the superconducting mechanisms yet exists, potential applications such as high-field magnets and Josephson devices have been explored. Indeed, a lot of reports about FBS tapes, wires, and even SQUIDs have been published to this date. In this thesis, the feasibility of high-field magnet applications of FBS is addressed by studying their transport properties, involving doped BaFe{sub 2}As{sub 2} (Ba-122) and LnFeAs(O,F) [Ln=Sm and Nd]. Particularly, it is important to study physical properties in a sample form (i.e. thin films) that is close to the conditions found in applications. However, the realisation of epitaxial FBS thin films is not an easy undertaking. Recent success in growing epitaxial FBS thin films opens a new avenue to delve into transport critical current measurements. The information obtained through this research will be useful for exploring high-field magnet applications. This thesis consists of 7 chapters: Chapter 1 describes the motivation of this study, the basic background of superconductivity, and a brief summary of the thin film growth of FBS. Chapter 2 describes experimental methods employed in this study. Chapter 3 reports on the fabrication of Co-doped Ba-122 thin films on various substrates. Particular emphasis lies on the discovery of fluoride substrates to be beneficial for

  4. Optics effects of splitting dipole magnets into several thin lenses

    CERN Document Server

    Leunissen, L H A

    1998-01-01

    The evaluation of the dynamic aperture and the calculation of non linear optics parameters have been made so far with the simplest model of dipole, i.e. a single thin lens positioned at the centre of each thick dipole. It was shown recently that the non-linear chromaticity decreases significantly when the thick lens is represented by two thin lenses or more instead of one. In this note the study is extended to amplitude detuning and dynamic aperture. Unlike the observation reported on non-linear chromatic detuning we find no significant changes for the dynamic aperture and amplitude d etuning when the dipole magnets are split in more than one thin lens. Furthermore, non-uniform azimuthal distribution of the multipoles inside the dipole is shown not to change the above-mentio ned results. In both cases, the influence of the beta-funtions is expected to give large effect for a given dipole. However, integrated over one cell this effect is shown to compensate to a large extent. erture reported on non-linear chro...

  5. Transport and Magnetism in Bulk and Thin Film Strontium Titanate

    Science.gov (United States)

    Ambwani, Palak

    SrTiO3 is a wide band-gap perovskite oxide semiconductor that is widely investigated in the bulk form, due to its remarkable electronic properties. These properties arise from its quantum paraelectric nature which enables unique features, such as, a high-mobility low-density metallic state, quantum transport in an unusual limit, and the most dilute superconducting state thus reported. Recent advances in deposition of oxide thin films and heterostructures have further led to some remarkable observations, such as, the strain-enhancement of mobility in doped thin films of SrTiO3, and the presence of 2D electron gases at interfaces and in delta-doped layers. The presence of magnetic moments and their possible ordering, and the simultaneous observation of quantum oscillations and superconductivity, have been reported in these 2D electron gases. While magnetism has been observed in heterostructures of SrTiO3 , there have been limited reports on magnetism in bulk SrTiO3. The first part of this thesis (Chapter 3) discusses how circularly polarized light can induce an extremely long-lived magnetic moment in slightly oxygen-deficient but otherwise nominally pure SrTiO3-delta bulk crystals. These magnetic signals, which are induced at zero applied magnetic field and at low temperatures below ˜ 18 K, can be controlled in both magnitude and sign by means of the circular polarization and wavelength of sub-bandgap illumination (400-500 nm), and point to the existence of optically polarizable VO-related complexes in the forbidden gap of SrTiO 3-delta, rather than collective or long-range magnetic order. The methods used to detect optically induced magnetization are also discussed (Appendix A). The phenomenal progress reported in thin films and heterostructures of SrTiO3 has been possible only by precise control of stoichiometry and defect density in SrTiO3 using techniques such as oxide/LASER MBE or high-temperature PLD. The next part of the thesis (Chapter 4) demonstrates that

  6. Axisymmetric Scattering of p Modes by Thin Magnetic Tubes

    CERN Document Server

    Hindman, Bradley W

    2011-01-01

    We examine the scattering of acoustic p-mode waves from a thin magnetic fibril embedded in a gravitationally stratified atmosphere. The scattering is mediated through the excitation of slow sausage waves on the magnetic tube, and only the scattering of the monopole component of the wavefield is considered. Since such tube waves are not confined by the acoustic cavity and may freely propagate along the field lines removing energy from the acoustic wavefield, the excitation of fibril oscillations is a source of acoustic wave absorption as well as scattering. We compute the mode mixing that is achieved and the absorption coefficients and phase shifts that would be measured in a Fourier-Hankel decomposition. We find that for thin tubes the mode mixing is weak and the absorption coefficient is small and is a smooth function of frequency over the physically relevant band of observed frequencies. The prominent absorption resonances seen in previous studies of unstratified tubes are absent. Despite the relatively sma...

  7. AXISYMMETRIC SCATTERING OF p MODES BY THIN MAGNETIC TUBES

    Energy Technology Data Exchange (ETDEWEB)

    Hindman, Bradley W. [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309-0440 (United States); Jain, Rekha, E-mail: hindman@solarz.colorado.edu [Applied Mathematics Department, University of Sheffield, Sheffield S3 7RH (United Kingdom)

    2012-02-10

    We examine the scattering of acoustic p-mode waves from a thin magnetic fibril embedded in a gravitationally stratified atmosphere. The scattering is mediated through the excitation of slow sausage waves on the magnetic tube, and only the scattering of the monopole component of the wave field is considered. Since such tube waves are not confined by the acoustic cavity and may freely propagate along the field lines removing energy from the acoustic wave field, the excitation of fibril oscillations is a source of acoustic wave absorption as well as scattering. We compute the mode mixing that is achieved and the absorption coefficients and phase shifts. We find that for thin tubes the mode mixing is weak and the absorption coefficient is small and is a smooth function of frequency over the physically relevant band of observed frequencies. The prominent absorption resonances seen in previous studies of unstratified tubes are absent. Despite the relatively small absorption, the phase shift induced can be surprisingly large, reaching values as high as 15 Degree-Sign for f modes. Further, the phase shift can be positive or negative depending on the incident mode order and the frequency.

  8. Microstructural, Magnetic Anisotropy, and Magnetic Domain Structure Correlations in Epitaxial FePd Thin Films with Perpendicular Magnetic Anisotropy

    Science.gov (United States)

    Skuza, J. R.; Clavero, C.; Yang, K.; Wincheski, B.; Lukaszew, R. A.

    2009-01-01

    L1(sub 0)-ordered FePd epitaxial thin films were prepared using dc magnetron sputter deposition on MgO (001) substrates. The films were grown with varying thickness and degree of chemical order to investigate the interplay between the microstructure, magnetic anisotropy, and magnetic domain structure. The experimentally measured domain size/period and magnetic anisotropy in this high perpendicular anisotropy system were found to be correlated following the analytical energy model proposed by Kooy and Enz that considers a delicate balance between the domain wall energy and the demagnetizing stray field energy.

  9. The large scale magnetic fields of thin accretion disks

    CERN Document Server

    Cao, Xinwu

    2013-01-01

    Large scale magnetic field threading an accretion disk is a key ingredient in the jet formation model. The most attractive scenario for the origin of such a large scale field is the advection of the field by the gas in the accretion disk from the interstellar medium or a companion star. However, it is realized that outward diffusion of the accreted field is fast compared to the inward accretion velocity in a geometrically thin accretion disk if the value of the Prandtl number Pm is around unity. In this work, we revisit this problem considering the angular momentum of the disk is removed predominantly by the magnetically driven outflows. The radial velocity of the disk is significantly increased due to the presence of the outflows. Using a simplified model for the vertical disk structure, we find that even moderately weak fields can cause sufficient angular momentum loss via a magnetic wind to balance outward diffusion. There are two equilibrium points, one at low field strengths corresponding to a plasma-bet...

  10. Magnetic domains in epitaxial BaFe12O19 thin films with perpendicular anisotropy

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.

    2002-01-01

    Magnetic domains, microstructure and magnetic properties of highly oriented barium ferrite thin films with perpendicular anisotropy have been investigated with magnetic force microscopy (MFM), VSM, SEM and TEM. Two kinds of magnetic domain are energetically favourable: (a) cluster-like structure in

  11. Study of the leakage field of magnetic force microscopy thin-film tips using electron holography

    NARCIS (Netherlands)

    Frost, B.G.; Hulst, van N.F.; Lunedei, E.; Matteucci, G.; Rikkers, E.

    1996-01-01

    Electron holography is applied for the study of the leakage field of thin-film ferromagnetic tips used as probes in magnetic force microscopy. We used commercially available pyramidal tips covered o­n o­ne face with a thin NiCo film, which were then placed in a high external magnetic field directed

  12. Magnetic properties and structure of very thin permalloy films

    Institute of Scientific and Technical Information of China (English)

    Guanghua Yu; Haifeng Li; Tao Yang; Fengwu Zhu

    2004-01-01

    In order to study the magnetic properties and structure of very thin permalloy films, Ni81Fe19 films of 12 nm in thickness were prepared by different instruments at an ultrahigh base vacuum and a lower base vacuum. The anisotropic magnetoresistance coefficients (△R/R) of Ni81Fe19 (12 nm) films reached 1.6 % and 0.6 %, and the coercivities were 127 and 334 A/m, respectively. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to study the structure and surface chemical state. The experimental results show that the films prepared at the ultrahigh base vacuum have a smoother surface, a bigger grain size and a denser structure with fewer defects than those prepared at the lower base vacuum.

  13. Interplay between electronic transport and magnetic order in ferromagnetic magnetic manganite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hundley, M.F.; Neumeier, J.J.; Heffner, R.H.; Jia, Q.X.; Wu, X.D.; Thompson, J.D.

    1997-05-01

    The transition metal oxides La{sub 1{minus}x}A{sub x}MnO{sub 3} (A = Ba, Ca, or Sr) order ferromagnetically with Curie temperatures ranging from as low as 50 K to well above room temperature. Magnetic order in these compounds results in a concomitant metal-insulator transition. The feature displayed by the manganites that is most important technologically is the extremely large negative magnetoresistance that achieves its largest values near the magnetic ordering temperature. Qualitatively, this colossal magnetoresistance (CMR) phenomenon involves the suppression of the relatively sharp maximum in the resistivity that is centered at T{sub C}. When considered collectively, the anomalous temperature-dependent transport properties, the CMR effect, and the magnetically ordered ground state indicate that a novel interplay between magnetism and electronic transport occurs in the manganites. General features of the magnetic-field and temperature-dependent electrical resistivity and magnetization as displayed by PLD-grown thin films are examined. Particular emphasis is placed on what these measurements tell us about the conduction process both above and below the magnetic ordering temperature.

  14. Structure and magnetic properties of thin films and superlattices

    CERN Document Server

    Bentall, M J

    2002-01-01

    Thin layers of rare earth elements and Laves phase superlattices were grown using molecular beam epitaxy. Their structure and magnetic properties have been probed using x-ray and neutron scattering, magnetisation measurements and high resolution electron microscopy. When holmium is grown on yttrium, the x-ray scattering from layers with a thickness below T sub c ' 115 A is characteristic of a pseudomorphic layer with the same in-plane lattice parameter as the yttrium substrate to within 0.05%. For layers above T sub c ' there is a sharp reduction in misfit strain which is probably due to the creation of edge dislocations. When gadolinium is grown on yttrium, no sharp change of strain of the thin layer was observed up to a thickness of 2920 A. This is characteristic of a pseudomorphic layer, and a failure to nucleate dislocations. For the Laves phase superlattices, a study of the x-ray scattering near several Bragg reflections revealed the presence of numerous superlattice peaks, showing that the samples exhib...

  15. Soft Magnetic Properties of High-Entropy Fe-Co-Ni-Cr-Al-Si Thin Films

    Directory of Open Access Journals (Sweden)

    Pei-Chung Lin

    2016-08-01

    Full Text Available Soft magnetic properties of Fe-Co-Ni-Al-Cr-Si thin films were studied. As-deposited Fe-Co-Ni-Al-Cr-Si nano-grained thin films showing no magnetic anisotropy were subjected to field-annealing at different temperatures to induce magnetic anisotropy. Optimized magnetic and electrical properties of Fe-Co-Ni-Al-Cr-Si films annealed at 200 °C are saturation magnetization 9.13 × 105 A/m, coercivity 79.6 A/m, out-of-plane uniaxial anisotropy field 1.59 × 103 A/m, and electrical resistivity 3.75 μΩ·m. Based on these excellent properties, we employed such films to fabricate magnetic thin film inductor. The performance of the high entropy alloy thin film inductors is superior to that of air core inductor.

  16. Magnetic reversal in iron thin films interspersed with non-magnetic pinning sites

    Energy Technology Data Exchange (ETDEWEB)

    Nau, Stefan; Wiedwald, Ulf; Wiedemann, Stefan; Plettl, Alfred; Ziemann, Paul [Institut fuer Festkoerperphysik, Universitaet Ulm (Germany)

    2010-07-01

    Magnetic switching of continuous iron thin films is tailored by structuring a periodic array of nonmagnetic holes acting as pinning centers for domain walls. Contrary to common lithographically prepared antidots, nanostructures are prepared by deposition of densely packed monolayers of polystyrene (PS) spheres on silicon and silicon nitride substrates. Isotropic plasma etching leads to adjustable PS diameters between 20% and 80% of the initial value while conserving the particle spacing. The influence on the magnetic reversal process is studied as a function of diameter and distance of the PS spheres. Iron films are deposited by pulsed laser deposition. Antidot arrays of 100 nm period lead to up to 15 times increased in-plane coercive fields at 300 K, depending on dot diameters and film thicknesses. The magnetic reversal is imaged by scanning transmission x-ray microscopy accompanied by micromagnetic simulations in order to understand domain nucleation and propagation in varying external fields.

  17. Narrow dip around zero magnetic field in magnetization hysteresis loops of thin YBCO superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Delimova, L [Wihuri Physical Laboratory, Department of Physics, University of Turku, FIN-20014 Turku (Finland); Liniichuk, I [A F Ioffe Physico-Technical Institute, St. Petersburg (Russian Federation); Laehderanta, E [Wihuri Physical Laboratory, Department of Physics, University of Turku, FIN-20014 Turku (Finland); Safonchik, M [Wihuri Physical Laboratory, Department of Physics, University of Turku, FIN-20014 Turku (Finland); Traito, K B [Wihuri Physical Laboratory, Department of Physics, University of Turku, FIN-20014 Turku (Finland)

    2003-01-01

    A narrow dip is observed around zero magnetic field in magnetization curves M(B) of superconducting YBCO films with about 10 nm thickness. This anomaly occurs in the same field range with an anomaly of ac surface impedance Z(B) found recently in thin YBCO films. Because the thickness of our films is considerably less than the London penetration depth, two-dimensional limit of the critical state model is applied. In the framework of this model the magnetic field dependence of the critical current density j{sub c}(B) is found. The obtained j{sub c}(B) function agrees well with that found in the ac surface impedance investigation.

  18. Study on characteristics of bias caused by FI-CE split flow electrokinetic injection

    Institute of Scientific and Technical Information of China (English)

    Luo Jinwen; Zhu Hailin; Li Huilin

    2006-01-01

    The characteristics of bias caused by split-flow electrokinetic injection(SEKI),a new type of sample injection method used in coupled flow injection-capillary electrophoresis system(FI-CE),was investigated using pseudoephedrine hydrochloride,a basic drug,and ibuprofen,an acidic drug,as model analytes.It was found that bias imposed by SEKI under the condition of continuous sample matrix/running buffer was similar to that done by electrokinetic injection(EKI).The linearity of calibration curve provided by SEKI was similar to that offered by non-bias hydrodynamic injection(HDI)but significantly better than that obtained by EKI.These features were exploited to improve analytical performances in simultaneous determination of the minor ingredient of pseudoephedrine hydrochloride and the major ingredient of ibuprofen in a pharmaceutical preparation.Detectability of 0.7 mg/l for pseudoephedrine hydrochloride was achieved at a sample throughput rate of 24 times per hour,which is 30%lower than that obtained by HDI-based conventional CE.Relative standard deviations(RSDs)of 2.8%for the minor ingredient and 1.2%for the major ingredient were produced in 11 runs of a test solution containing 13.1 mg/l pseudoephedrine hydrochloride and 81.4 mg/l ibuprofen.This is an improvement compared to that obtained by HDI-based conventional CE.Analytical results for two batches of compound ibuprofen tablets by the SEKI-based FI-CE approach were in good agreement with that obtained by a conventional high performance liquid chromatographic method.

  19. Method for controlling start-up and steady state performance of a closed split flow recompression brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Pasch, James Jay

    2017-02-07

    A method of resolving a balanced condition that generates control parameters for start-up and steady state operating points and various component and cycle performances for a closed split flow recompression cycle system. The method provides for improved control of a Brayton cycle thermal to electrical power conversion system. The method may also be used for system design, operational simulation and/or parameter prediction.

  20. Perpendicular magnetic anisotropy of Au/FePt thin films grown on Si substrates

    CERN Document Server

    Lee, Y W; Kim, C O

    1999-01-01

    FePt thin films show in plane magnetism with a very large coercive force when they are deposited on lattice-mismatched substrates, such as glass or Si In our research, FePt alloy thin films were deposited, using the coevaporation method, on a Au buffer layer which was evaporated onto a Si substrate at 500 .deg. C. The magnetic easy axis of the FePt film changed from the in-plane direction to the normal direction of the film. Therefore, it can be said that a Au buffer layer can enhance the perpendicular magnetic anisotropy of a FePt thin film on a lattice-mismatched substrate.

  1. Electric field-controlled magnetization switching in Co/Pt thin-film ferromagnets

    Directory of Open Access Journals (Sweden)

    A. Siddique

    2016-12-01

    Full Text Available A study of dynamic and reversible voltage-controlled magnetization switching in ferromagnetic Co/Pt thin film with perpendicular magnetic anisotropy at room temperature is presented. The change in the magnetic properties of the system is observed in a relatively thick film of 15 nm. A surface charge is induced by the formation of electrochemical double layer between the metallic thin film and non-aqueous lithium LiClO4 electrolyte to manipulate the magnetism. The change in the magnetic properties occurred by the application of an external electric field. As the negative voltage was increased, the coercivity and the switching magnetic field decreased thus activating magnetization switching. The results are envisaged to lead to faster and ultra-low-power magnetization switching as compared to spin-transfer torque (STT switching in spintronic devices.

  2. Magnetic and optical properties of the nickel thin film deposited by GLAD technique

    Directory of Open Access Journals (Sweden)

    Potočnik Jelena M.

    2014-01-01

    Full Text Available In this work, nickel thin film was deposited on glass sample using Glancing Angle Deposition (GLAD technique, to a thickness of 1 μm. Glass sample was positioned 15 degrees with respect to the nickel vapor flux. The nickel thin film was characterized by Atomic Force Microscopy (AFM, Magneto- Optical Kerr effect Microscopy and Spectroscopic Ellipsometry. According to an AFM cross-section imaging, it was found that the nickel thin film has a columnar structure. The values of the coercively, obtained from the magnetic hysteresis loops, were analyzed as a function of the sample rotation in the magnetic field. It was found that the direction of magnetization easy axis lies toward the structure growth. Optical properties of the nickel thin film were studied at the wavelength of 455 nm. From the shape of the refractive index and the extinction coefficient diagrams could be concluded that the nickel thin film has an optical anisotropy.

  3. A comparison study of Co and Cu doped MgO diluted magnetic thin films

    Science.gov (United States)

    Sarıtaş, S.; ćakıcı, T.; Muǧlu, G. Merhan; Kundakcı, M.; Yıldırım, M.

    2017-02-01

    Transition metal-doped MgO diluted magnetic thin films are appropriate candidates for spintronic applications and designing magnetic devices and sensors. Therefore, MgO:Co and MgO:Cu films were deposited on glass substrates by Chemical Spray Pyrolysis (CSP) method different thin film deposition parameters. Deposited different transition metal doped MgO thin films were compared in terms of optic and structural properties. Comparison optic analysis of the films was investigated spectral absorption and transmittance measurements by UV-Vis double beam spectrophotometer technique. Comparison structural analysis of the thin films was examined by using XRD, Raman Analysis, SEM, EDX and AFM techniques. The transition metal-doped; MgO:Co and MgO:Cu thin films maybe have potential applications in spintronics and magnetic data storage.

  4. MFM Study: the Air Damping Effect on Magnetic Imaging of CoNbZr Thin Film

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-hong; CHEN Kun; ZHOU Yu; SHEN Bo-kan

    2007-01-01

    This paper studies the CoNbZr soft magnetic thin film by magnetic force microscopy (MFM). By measuring in atmosphere circumstance, the magnetic force images display some clear dark dots which are corresponding to the clusters in the topography images well. Then the dark dots disappear in magnetic force images, scanning in high vacuum. This indicates that the dark dots are caused by air damping between the vibrating tip and the sample. An interpretation for the above observation is given.

  5. Observation of the stray field of thin film magnetic tips using electron holography

    NARCIS (Netherlands)

    Lunedei, E.; Matteucci, G.; Frost, B.G.; Greve, J.

    1996-01-01

    The stray field around thin film ferromagnetic tips employed for magnetic force microscopy has been revealed using electron holography. The experimental phase difference maps are in good agreement with simulations. Quantitative flux measurements of the leakage field are obtained.

  6. PHYSICAL BASES OF SYSTEMS CREATION FOR MAGNETIC-IMPULSIVE ATTRACTION OF THIN-WALLED SHEET METALS

    Directory of Open Access Journals (Sweden)

    Y. Batygin

    2009-01-01

    Full Text Available The work is dedicated to the physical base of systems creating for the thin-walled sheet metals magnetic pulse attraction. Some practical realization models of the author’s suggestions are represented.

  7. TOF-SIMS analysis: Application to ultra-thin AWA film on magnetic head

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    F-containing polymer was coated on the magnetic head of hard disc drive (HDD) as theultra-thin (<20(?)) film of anti-wetting agent (AWA). A static TOF-SIMS method has been applied tomeasuring the thickness and coating uniformity of the ultra-thin film. TOF- SIMS is also used tostudy the micro-tribology and transfer of lubricant between the magnetic head and media interface.

  8. Stabilization of helical magnetic structures in thin multilayers

    OpenAIRE

    Dzemiantsova, L. V.; Meier, G.; R. Röhlsberger

    2014-01-01

    Based on micromagnetic simulations, we report on a novel helical magnetic structure in a soft magnetic film that is sandwiched between and exchange-coupled to two hard magnetic layers. Confined between antiparallel hard magnetic moments, a helix with a turn of 180$^{\\circ}$ is stable without the presence of an external magnetic field. The magnetic stability is determined by the energy minimization and is a result of an internal field created by exchange interaction and anisotropy. Since the i...

  9. Preparation of Mn{sub 3-x}Ga Heusler thin films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Glas, Manuel; Ebke, Daniel; Thomas, Patrick; Reiss, Guenter [Thin Films and Physics of Nanostructures, Physics Department, Bielefeld University (Germany)

    2011-07-01

    Recently, the integration of materials with perpendicular magnetic anisotropy into magnetic tunnel junctions (MTJs) has found a lot of attraction due to the predicted lowered current densities for spin transfer switching and a higher thermal stability. Because of the predicted high spin polarization and the low magnetic moment Mn{sub 3}Ga is a promising material for future spin torque transfer (STT) magnetic switching devices. For this work, we have fabricated Mn{sub 3-x}Ga Heusler thin films with varying stoichiometries into half magnetic tunnel junctions. The effect of Heusler film composition will be discussed with respect to the magnetic and crystal properties.

  10. Magnetoimpedance exchange coupling in different magnetic strength thin layers electrodeposited on Co-based magnetic ribbons

    Science.gov (United States)

    Jamilpanah, L.; Hajiali, M. R.; Morteza Mohseni, S.; Erfanifam, S.; Majid Mohseni, S.; Houshiar, M.; Ehsan Roozmeh, S.

    2017-04-01

    A systematic study of the effect of the deposition of cobalt (Co) and nickel (Ni) layers of various thicknesses on the magnetoimpedance (MI) response of a soft ferromagnetic amorphous ribbon (Co68.15Fe4.35Si12.5B15) is performed. The Co and Ni layers with thicknesses of 5, 10, 20 and 40 nm were grown on both sides of the amorphous ribbons by the electrodeposition technique. Microstrutures determined by x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) showed higher crystallinity of Ni-deposited layers and the amorphous ferromagnetic nature of Co-deposited. The vibrating sample magnetometry (VSM) does not represent significant changes between samples because of the small contribution of such a thin layer deposited on thick ribbons, but the MI response dictates that the magnetic coupling effect occurred at the interface of such bilayers, which is sensitive to the skin effect. The MI response of Co-deposited ribbons showed MI hysteretic behavior depending on the deposited layer thicknesses with an optimum response for the thickness of 20 nm whereas no hysteretic behavior was measured for Ni-deposited ribbons. This behavior is explained according to the exchange coupling between magnetization of electrodeposited layers and magnetic ribbons with respect to different magnetic properties of Co and Ni at different thicknesses. Also the MI response of Ni- and Co-deposited ribbons enhanced significantly at low thicknesses relative to bare ribbon. By increasing the thickness of deposited layers, MI response decreases considerably. Differences in MI ratios of Co- and Ni-deposited ribbons are explained according to exchange length, crystallinity and roughness of deposited layers. Our results could address a simple way to achieve a higher MI response, and explains physical aspects of exchange coupling in MI response all towards a better performance of magnetic field sensors.

  11. Magnetic domain observation of FeCo thin films fabricated by alternate monoatomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsuki, T., E-mail: ohtsuki@spring8.or.jp; Kotsugi, M.; Ohkochi, T. [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kojima, T.; Mizuguchi, M.; Takanashi, K. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2014-01-28

    FeCo thin films are fabricated by alternate monoatomic layer deposition method on a Cu{sub 3}Au buffer layer, which in-plane lattice constant is very close to the predicted value to obtain a large magnetic anisotropy constant. The variation of the in-plane lattice constant during the deposition process is investigated by reflection high-energy electron diffraction. The magnetic domain images are also observed by a photoelectron emission microscope in order to microscopically understand the magnetic structure. As a result, element-specific magnetic domain images show that Fe and Co magnetic moments align parallel. A series of images obtained with various azimuth reveal that the FeCo thin films show fourfold in-plane magnetic anisotropy along 〈110〉 direction, and that the magnetic domain structure is composed only of 90∘ wall.

  12. Aspects of passive magnetic levitation based on high-T(sub c) superconducting YBCO thin films

    Science.gov (United States)

    Schoenhuber, P.; Moon, F. C.

    1995-01-01

    Passive magnetic levitation systems reported in the past were mostly confined to bulk superconducting materials. Here we present fundamental studies on magnetic levitation employing cylindrical permanent magnets floating above high-T(sub c) superconducting YBCO thin films (thickness about 0.3 mu m). Experiments included free floating rotating magnets as well as well-established flexible beam methods. By means of the latter, we investigated levitation and drag force hysteresis as well as magnetic stiffness properties of the superconductor-magnet arrangement. In the case of vertical motion of the magnet, characteristic high symmetry of repulsive (approaching) and attractive (withdrawing) branches of the pronounced force-displacement hysteresis could be detected. Achievable force levels were low as expected but sufficient for levitation of permanent magnets. With regard to magnetic stiffness, thin films proved to show stiffness-force ratios about one order of magnitude higher than bulk materials. Phenomenological models support the measurements. Regarding the magnetic hysteresis of the superconductor, the Irie-Yamafuji model was used for solving the equation of force balance in cylindrical coordinates allowing for a macroscopic description of the superconductor magnetization. This procedure provided good agreement with experimental levitation force and stiffness data during vertical motion. For the case of (lateral) drag force basic qualitative characteristics could be recovered, too. It is shown that models, based on simple asymmetric magnetization of the superconductor, describe well asymptotic transition of drag forces after the change of the magnet motion direction. Virgin curves (starting from equilibrium, i.e. symmetric magnetization) are approximated by a linear approach already reported in literature only. This paper shows that basic properties of superconducting thin films allow for their application to magnetic levitation or - without need of levitation

  13. Aspects of passive magnetic levitation based on high-T(sub c) superconducting YBCO thin films

    Science.gov (United States)

    Schoenhuber, P.; Moon, F. C.

    1995-04-01

    Passive magnetic levitation systems reported in the past were mostly confined to bulk superconducting materials. Here we present fundamental studies on magnetic levitation employing cylindrical permanent magnets floating above high-T(sub c) superconducting YBCO thin films (thickness about 0.3 mu m). Experiments included free floating rotating magnets as well as well-established flexible beam methods. By means of the latter, we investigated levitation and drag force hysteresis as well as magnetic stiffness properties of the superconductor-magnet arrangement. In the case of vertical motion of the magnet, characteristic high symmetry of repulsive (approaching) and attractive (withdrawing) branches of the pronounced force-displacement hysteresis could be detected. Achievable force levels were low as expected but sufficient for levitation of permanent magnets. With regard to magnetic stiffness, thin films proved to show stiffness-force ratios about one order of magnitude higher than bulk materials. Phenomenological models support the measurements. Regarding the magnetic hysteresis of the superconductor, the Irie-Yamafuji model was used for solving the equation of force balance in cylindrical coordinates allowing for a macroscopic description of the superconductor magnetization. This procedure provided good agreement with experimental levitation force and stiffness data during vertical motion. For the case of (lateral) drag force basic qualitative characteristics could be recovered, too. It is shown that models, based on simple asymmetric magnetization of the superconductor, describe well asymptotic transition of drag forces after the change of the magnet motion direction. Virgin curves (starting from equilibrium, i.e. symmetric magnetization) are approximated by a linear approach already reported in literature only. This paper shows that basic properties of superconducting thin films allow for their application to magnetic levitation or - without need of levitation

  14. Magnetic and magnetostrictive properties of amorphous TbFe/FeAl multilayer thin film

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; MI Yiming; QIAN Shiqiang; ZHOU Xiying

    2008-01-01

    Exchange coupling multilayer thin films, which combined giant magnetostriction and soft magnetic properties, were of growing interest for applications. The TbFe/FeAl multilayer thin films were prepared by dc magnetron sputtering onto glass substrates. The microstructure, magnetic, and magnetostrictive properties of TbFe/FeAl multilayer thin film was investigated at different annealing temperatures. The results indicated that the soft magnetic and magnetostrictive properties for TbFe/FeAl multilayer thin film compared with TbFe single layer film were obviously improved. In comparison with the intrinsic coercivity JHc of 59.2 kA/m for TbFe single layer film, the intrinsic coercivity JHc for TbFe/FeAl multilayer thin films rapidly dropped to 29.6 kA/m. After optimal annealing (350 ℃×60 min), magnetic properties of Hs=96 kA/m and JHc=16 kA/m were obtained, and magnetostrictive coefficient could reach to 574×10-6 under an external magnetic field of 400 kA·m-1 for the TbFe/FeAl multilayer thin film.

  15. Anisotropic behaviour of transmission through thin superconducting NbN film in parallel magnetic field

    Science.gov (United States)

    Šindler, M.; Tesař, R.; Koláček, J.; Skrbek, L.

    2017-02-01

    Transmission of terahertz waves through a thin layer of the superconductor NbN deposited on an anisotropic R-cut sapphire substrate is studied as a function of temperature in a magnetic field oriented parallel with the sample. A significant difference is found between transmitted intensities of beams linearly polarised parallel with and perpendicular to the direction of applied magnetic field.

  16. The dynamics of the Soret effect in thin film of magnetic fluid

    NARCIS (Netherlands)

    Kopcansky, P; Tomco, L; Timko, M; Koneracka, M; Turek, F; Stelina, J; Musil, C; Ocelik, Vaclav

    2000-01-01

    The Soret effect in interference field of two intensive laser beams in the thin film of magnetic fluid was used to create a periodical structure of density of magnetic particles. The structures obtained were indicated using the self-diffraction of the optical beam creating the structures. The relaxa

  17. The dynamics of the Soret effect in thin film of magnetic fluid

    NARCIS (Netherlands)

    Kopcansky, P; Tomco, L; Timko, M; Koneracka, M; Turek, F; Stelina, J; Musil, C; Ocelik, Vaclav

    The Soret effect in interference field of two intensive laser beams in the thin film of magnetic fluid was used to create a periodical structure of density of magnetic particles. The structures obtained were indicated using the self-diffraction of the optical beam creating the structures. The

  18. Perpendicular Magnetic Anisotropy in Fe-N Thin Films: Threshold Field for Irreversible Magnetic Stripe Domain Rotation

    Science.gov (United States)

    Garnier, L.-C.; Eddrief, M.; Fin, S.; Bisero, D.; Fortuna, F.; Etgens, V. H.; Marangolo, M.

    The magnetic properties of an iron nitride thin film obtained by ion implantation have been investigated. N2+ ions were implanted in a pristine iron layer epitaxially grown on ZnSe/GaAs(001). X-ray diffraction measurements revealed the formation of body-centered tetragonal N-martensite whose c-axis is perpendicular to the thin film plane and c-parameter is close to that of α‧-Fe8N. Magnetic measurements disclosed a weak perpendicular magnetic anisotropy (PMA) whose energy density KPMA was assessed to about 105J/m3. A sharp decline of the in-plane magnetocrystalline anisotropy (MCA) was also observed, in comparison with the body-centered cubic iron. The origin of the PMA is attributed to the MCA of N-martensite and/or stress-induced anisotropy. As a result of the PMA, weak magnetic stripe domains with a period of about 130nm aligned along the last saturating magnetic field direction were observed at remanence by magnetic force microscopy. The application of an increasing in-plane magnetic field transverse to the stripes Htrans highlighted a threshold value (μ0Htrans≈0.1T) above which these magnetic domains irreversibly rotated. Interestingly, below this threshold, the stripes do not rotate, leading to a zero remanent magnetization along the direction of the applied field. The interest of this system for magnetization dynamics is discussed.

  19. Magnetic and electric properties of C-Co thin films prepared by vaccum arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Tembre, A.; Clin, M.; Picot, J.-C. [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Dellis, J.-L., E-mail: jean-luc.dellis@u-picardie.fr [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Henocque, J. [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Bouzerar, R. [Laboratoire de Physique des Systemes Complexes, Universite de Picardie Jules Verne, 33 rue Saint leu, 80039 Amiens (France); Djellab, K. [Plate-forme de Microscopie Electronique, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France)

    2011-09-15

    Highlights: > Cobalt doped carbon thin films have been deposited by pulsed anodic electric arc technique. > The films are composed of well-crystallized cobalt layers and complex graphitic microstructure. > An insulating to a metallic state transition at 60 K is observed. > The magnetic susceptibility measurements show anomalous behaviour around 60 K. - Abstract: Cobalt doped carbon thin films have been deposited by a pulsed anodic electric arc technique. The films were characterized by high resolution transmission electron microscopy, electric measurements under dc magnetic fields, and ac magnetic susceptibility measurements within a temperature range 15-300 K. An insulating to a metallic state transition at a critical temperature around 60 K was observed.

  20. CONDITIONS FOR TRANSVERSE WAVES PROPAGATION ALONG THIN MAGNETIC FLUX TUBES ON THE SUN

    Energy Technology Data Exchange (ETDEWEB)

    Lopin, Igor [Ussuriisk Astrophysical Observatory, Russian Academy of Sciences, Ussuriisk (Russian Federation); Nagorny, Ivan, E-mail: lopin78@mail.ru [Institute of Automation and Control Processes FEB RAS, Vladivostok (Russian Federation)

    2013-09-10

    The propagation of kink waves in the thin gravity stratified flux tubes with a generalized magnetic field distribution model is considered in cylindrical geometry. The new kink wave equations for both wave variables are obtained. It is shown that the inclusion of the radial component of an unperturbed tube magnetic field sufficiently transforms the conditions for the propagation of transverse waves. It is demonstrated that, for the models of isothermal and polytropic atmosphere in the tube and its environment, the propagation of kink waves along thin magnetic flux tubes is cutoff-free.

  1. Magnetization states in epitaxial thin films subjected to misfit strains and demagnetization field

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Junqing [Department of Applied Mathematics, School of Science, Zhejiang University of Technology, Hangzhou, Zhejiang 310014 (China); Wang, Jie, E-mail: jw@zju.edu.cn [Institute of Applied Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2015-01-15

    The effect of non-equally biaxial in-plane misfit strains and demagnetization field on the magnetization states of ferromagnetic thin films is analytically investigated by using a nonlinear thermodynamic theory. The “misfit strain–misfit strain” phase diagrams of the magnetization states at room temperature for α-Fe and CoFe{sub 2}O{sub 4} thin films epitaxially grown on tetragonal substrates are developed by minimizing the total free energy. For a cubic ferromagnetic thin film, an out-of-plane magnetization state exists in the region of tensile misfit strains if the magnetostrictive coefficient of λ{sub 100} is negative and the demagnetization field is small, whereas the out-of-plane magnetization vanishes in the whole region of misfit strains when the demagnetization field is large.

  2. Tailoring the optical bandgap and magnetization of cobalt ferrite thin films through controlled zinc doping

    Directory of Open Access Journals (Sweden)

    Deepanshu Sharma

    2016-08-01

    Full Text Available In this report, the tuning of the optical bandgap and saturation magnetization of cobalt ferrite (CFO thin films through low doping of zinc (Zn has been demonstrated. The Zn doped CFO thin films with doping concentrations (0 to 10% have been synthesized by ultrasonic assisted chemical vapour deposition technique. The optical bandgap varies from 1.48 to 1.88 eV and saturation magnetization varies from 142 to 221 emu/cc with the increase in the doping concentration and this change in the optical and magnetic properties is attributed to the change in the relative population of the Co2+ at the tetrahedral and octahedral sites. Raman study confirms the decrease in the population of Co2+ at tetrahedral sites with controlled Zn doping in CFO thin films. A quantitative analysis has been presented to explain the observed variation in the optical bandgap and saturation magnetization.

  3. Magnetic field induced switching of the antiferromagnetic order parameter in thin films of magnetoelectric chromia

    Science.gov (United States)

    Fallarino, Lorenzo; Berger, Andreas; Binek, Christian

    2015-02-01

    A Landau-theoretical approach is utilized to model the magnetic field induced reversal of the antiferromagnetic order parameter in thin films of magnetoelectric antiferromagnets. A key ingredient of this peculiar switching phenomenon is the presence of a robust spin polarized state at the surface of the antiferromagnetic films. Surface or boundary magnetization is symmetry allowed in magnetoelectric antiferromagnets and experimentally established for chromia thin films. It couples rigidly to the antiferromagnetic order parameter and its Zeeman energy creates a pathway to switch the antiferromagnet via magnetic field application. In the framework of a minimalist Landau free energy expansion, the temperature dependence of the switching field and the field dependence of the transition width are derived. Least-squares fits to magnetometry data of (0001 ) textured chromia thin films strongly support this model of the magnetic reversal mechanism.

  4. Engineering Gilbert damping by dilute Gd doping in soft magnetic Fe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W., E-mail: xiaotur@gmail.com; Jiang, S.; Sun, L.; Wang, Y. K.; Zhai, Y. [Department of Physics, Southeast University, Nanjing 211189 (China); Wong, P. K. J.; Wang, K.; Jong, M. P. de; Wiel, W. G. van der [NanoElectronics Group, MESA Institute for Nanotechnology, P.O. Box 217, 7500 AE Enschede (Netherlands); Laan, G. van der [Diamond Light Source, Magnetic Spectroscopy Group, Didcot OX11 0DE (United Kingdom)

    2014-05-07

    By analyzing the ferromagnetic resonance linewidth, we show that the Gilbert damping constant in soft magnetic Fe thin films can be enhanced by ∼6 times with Gd doping of up to 20%. At the same time, the magnetic easy axis remains in the film plane while the coercivity is strongly reduced after Gd inclusion. X-ray magnetic circular dichroism measurements reveal a strong increase in the orbital-to-spin moment ratio of Fe with increasing Gd concentration, in full agreement with the increase in the Gilbert damping obtained for these thin films. Combined with x-ray diffraction and vibrating sample magnetometry, the results demonstrate that the FeGd thin films with dilute Gd doping of up to 20% are promising candidates for spin-transfer-torque applications in soft magnetic devices, in which an enhanced damping is required.

  5. Magnetic Properties of Heisenberg Thin Films in an External Field

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong; ZHANG Jing

    2004-01-01

    The magnetic properties of Heisenberg ferromagnetic films in an external magnetic field are investigated by means of the variational cumulant expansion (VCE). The magnetization can be in principle calculated analytically as the function of the temperature and the number of atomic layers in the film to an arbitrary order of accuracy in the VCE. We calculate the spontaneous magnetization and coercivity to the third order for spin-1/2 Heisenberg films with simple cubic lattices by using a graphic technique.

  6. Macroscopic fields in thin ferromagnetic sheets taking into account eddy currents and Landau-Lifshitz magnetization

    Science.gov (United States)

    Dupré, Luc; Olyslager, Frank; Melkebeek, Jan

    2004-05-01

    The paper deals with a numerical model for the evaluation of the electromagnetic behavior in thin magnetic sheets. Therefore, we consider Maxwell's equations together with a nonlinear magnetic constitutive law described by the Landau-Lifshitz equation. We present a suitable numerical approximation based upon a finite element-finite difference method. At each time step in the numerical scheme, the magnetization dynamics is calculated analytically by introducing for each finite element node a transformation towards a local coordinate system.

  7. Magnetic moment jumps in flat and nanopatterned Nb thin-walled cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Tsindlekht, M.I., E-mail: mtsindl@vms.huji.ac.il [The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Genkin, V.M.; Felner, I.; Zeides, F.; Katz, N. [The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Gazi, Š.; Chromik, Š. [The Institute of Electrical Engineering SAS, Dúbravská cesta 9, 84104 Bratislava (Slovakia); Dobrovolskiy, O.V. [Physikalisches Institut, Goethe University, 60438 Frankfurt am Main (Germany); Physics Department, V. Karazin Kharkiv National University, 61077 Kharkiv (Ukraine); Sachser, R.; Huth, M. [Physikalisches Institut, Goethe University, 60438 Frankfurt am Main (Germany)

    2017-02-15

    Highlights: • Magnetization curves of as-prepared and patterned thin-walled cylinders were measured in magnetic fields applied parallel to cylinders axis. • Magnetic moment jumps were observed in magnetic fields lower and above Hc1. • Critical current density in isthmus between two antidots is higher than in a film itself. - Abstract: Penetration of magnetic flux into hollow superconducting cylinders is investigated by magnetic moment measurements. The magnetization curves of a flat and a nanopatterned thin-walled superconducting Nb cylinders with a rectangular cross section are reported for the axial field geometry. In the nanopatterned sample, a row of micron-sized antidots (holes) was milled in the film along the cylinder axis. Magnetic moment jumps are observed for both samples at low temperatures for magnetic fields not only above H{sub c1}, but also in fields lower than H{sub c1}, i. e., in the vortex-free regime. The positions of the jumps are not reproducible and they change from one experiment to another, resembling vortex lattice instabilities usually observed for magnetic fields larger than H{sub c1}. At temperatures above 0.66T{sub c} and 0.78T{sub c} the magnetization curves become smooth for the patterned and the as-prepared sample, respectively. The magnetization curve of a reference flat Nb film in the parallel field geometry does not exhibit jumps in the entire range of accessible temperatures.

  8. Entropy localization in magnetic compounds and thin-film nanostructures

    Science.gov (United States)

    Skomski, R.; Binek, Ch.; Michalski, S.; Mukherjee, T.; Enders, A.; Sellmyer, D. J.

    2010-05-01

    The effect of nanostructuring on the magnetic entropy of materials for room-temperature magnetic cooling is investigated by model calculations. The materials are structurally inhomogeneous with a large number of nonequivalent crystallographic sites. In the mean-field Heisenberg model, the entropy density is a unique function of the local magnetization so that the coupled set of nonlinear mean-field equations yields not only the magnetization but also the entropy density. Since most of the entropy is localized near grain boundaries, nanomagnetic cooling requires small feature sizes. Magnetic anisotropy is a substantial complication, even on a mean-field level, but the corresponding corrections are often very small.

  9. Temperature-driven changes of order and magnetism in FePd thin films and thin foil

    Energy Technology Data Exchange (ETDEWEB)

    Issro, Ch. [Institut fuer Materialphysik, University of Vienna, Strudlhofgasse 4, 1090 Vienna (Austria); Pueschl, W. [Institut fuer Materialphysik, University of Vienna, Strudlhofgasse 4, 1090 Vienna (Austria); Pfeiler, W. [Institut fuer Materialphysik, University of Vienna, Strudlhofgasse 4, 1090 Vienna (Austria)]. E-mail: pfeiler@ap.univie.ac.at; Rogl, P.F. [Institut fuer Physikalische Chemie, University of Vienna, Waehringerstrasse 42, 1090 Vienna (Austria); Soffa, W.A. [Department of Material Science and Engineering, University of Pittsburgh, 842 Benedum Hall, Pittsburgh, PA 15261 (United States); Acosta, M. [M. Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, 30-059 Cracow (Poland); Schmerber, G. [M. Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, 30-059 Cracow (Poland); Kozubski, R. [IPCMS-GEMME, CNRS-ULP, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Pierron-Bohnes, V. [M. Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, 30-059 Cracow (Poland)

    2005-08-15

    FePd thin films (thickness: 50 nm, co-sputtered or co-deposited by molecular beam epitaxy) and bulk foil (cold-rolled to 10 {mu}m thickness) were studied during isochronal heat treatment. The influence of thermal treatment on X-ray diffraction, electrical resistivity (in-plane) and magnetization (in-plane and out-of-plane) are compared in the different systems.

  10. Stabilization of magnetic helix in exchange-coupled thin films.

    Science.gov (United States)

    Dzemiantsova, L V; Meier, G; Röhlsberger, R

    2015-11-05

    Based on micromagnetic simulations, we report on a novel magnetic helix in a soft magnetic film that is sandwiched between and exchange-coupled to two hard magnetic layers with different anisotropies. We show that such a confined helix stays stable without the presence of an external magnetic field. The magnetic stability is determined by the energy minimization and is a result of an internal magnetic field created by the exchange interaction. We show that this internal field stores a magnetic energy density of a few kJ/m(3). We also find that it dramatically modifies ferromagnetic resonances, such that the helix can be used as a ferromagnetic resonance filter and a fast acting attenuator.

  11. Field dependent magnetic anisotropy of Fe1-xZnx thin films

    Science.gov (United States)

    Resnick, Damon A.; McClure, A.; Kuster, C. M.; Rugheimer, P.; Idzerda, Y. U.

    2013-05-01

    Using longitudinal magneto-optical Kerr effect in combination with a variable strength rotating magnetic field, called the Rotational Magneto-Optic Kerr Effect (ROTMOKE) method, we show that the magnetic anisotropy for thin Fe82Zn18 single crystal films, grown on MgO(001) substrates, depends linearly on the strength of the applied magnetic field at low fields but is constant (saturates) at fields greater than 350 Oe. The torque moment curves generated using ROTMOKE are well fit with a model that accounts for the uniaxial and cubic anisotropy with the addition of a cubic anisotropy that depends linearly on the applied magnetic field. The field dependent term is evidence of a large effect on the effective magnetic anisotropy in Fe1-xZnx thin films by the magnetostriction.

  12. Magnetic relaxation and dipole-coupling-induced magnetization in nanostructured thin films during growth: A cluster Monte Carlo study

    Science.gov (United States)

    Brinzanik, R.; Jensen, P. J.; Bennemann, K. H.

    2003-11-01

    For growing inhomogeneous thin films with an island nanostructure similar to that observed in experiment we determine the nonequilibrium and the equilibrium remanent magnetization. The single-island magnetic anisotropy, the dipole coupling, and the exchange interaction between magnetic islands are taken into account within a micromagnetic model. A cluster Monte Carlo method is developed which includes coherent magnetization changes of connected islands. This causes a fast relaxation towards equilibrium for irregularly connected systems. We analyze the transition from dipole coupled islands at low coverages to a strongly connected ferromagnetic film at high coverages during film growth. For coverages below the percolation threshold the dipole interaction induces a collective magnetic order with ordering temperatures of 1 10 K for the assumed model parameters. Anisotropy causes blocking temperatures of 10 100 K and thus pronounced nonequilibrium effects. The dipole coupling leads to a somewhat slower magnetic relaxation.

  13. Magnetic nanopatterning of CoPt thin layers

    Energy Technology Data Exchange (ETDEWEB)

    Abes, M. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France); Venuat, J. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France); Carvalho, A. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France); Arabski, J. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France); Muller, D. [Laboratoire Phase, CNRS-UPR292, 23 rue du Loess, 67034 Strasbourg, Cedex 2 (France); Schmerber, G. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France); Beaurepaire, E. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France); Panissod, P. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France); Dinia, A. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France); Pierron-Bohnes, V. [Institut de Physique et de Chimie des Materiaux de Strasbourg (UMR 7504 du CNRS), ULP-ECPM-CNRS, BP 43, 23 rue du Loess, 67034 Strasbourg, Cedex, 2 (France)]. E-mail: veronique.pierron-bohnes@oipcms.u-strasbg.fr

    2005-02-01

    Ionic irradiation is used to magnetically pattern CoPt alloy films, using an appropriate mask to protect arrays of CoPt dots with a 1 {mu}m{sup 2} size, while the remainder of the film is exposed to ionic irradiation. Before irradiation, we obtain a layer with the Ll{sub 0} tetragonal structure, ordered and with a strong perpendicular magnetic anisotropy energy in the growth direction. After irradiation, the unprotected regions become disordered and magnetically soft, whereas the protected regions remain magnetically hard. Spatially selective irradiation thus provides a spatial distribution of magnetic anisotropy and hence of the magnetization direction, perpendicular to plane in the ordered zones and in-plane in the disordered zones. The interest of ionic irradiation is that the film recovers its initial roughness after elimination of the mask which is promising for the data storage applications.

  14. Orbital magnetic moments in SrRu O3 epitaxial thin films with interfacially controlled magnetic anisotropy

    Science.gov (United States)

    Kan, Daisuke; Mizumaki, Masaichiro; Nishimura, Tomoe; Shimakawa, Yuichi

    2016-12-01

    Using x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) spectroscopy, we evaluated the orbital magnetic moments of itinerant ferromagnet SrRu O3 (SRO) epitaxial thin films with interfacially controlled magnetic anisotropy. We found that the orbital moment is closely correlated with the SRO's magnetic anisotropy, which can be controlled by interfacially engineering the Ru O6 octahedral rotations. For the monoclinic film with magnetization along the direction 45° from the out-of-plane direction, the orbital moment is ≈-0.1 μB/Ru along the magnetic easy axis direction and is aligned antiparallel to the direction of the spin magnetic moments. For the tetragonal film with in-plane magnetization, on the other hand, the out-of-plane component of the orbital moment is as small as ≈-0.04 μB/Ru , accounting for the film's in-plane magnetic anisotropy. Our results highlight that the magnetic anisotropy of SRO can be controlled by engineering the orbital magnetic moment through the octahedral distortions.

  15. Structure, magnetization, and magnetostriction of Sm-R-Fe (R = Pr, Nd) thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Bowen; CAO Shuying; WENG Ling; HUANG Wenmei; SUN Ying

    2006-01-01

    The structure, magnetization, and magnetostriction of Sm0.9Pr0.1Fex and Sm1-xNdxFe1.9 thin films have been investigated using X-ray diffraction, vibrating sample magnetometer, and optical cantilever method. It is found that the structure of Sm0.9Pr0.1Fex thin films consists of an Sm-Pr-Fe amorphous phase when x ≤ 2.69 and that of Sm1-xNdxFe1.9 thin films consists of an Sm-Nd-Fe amorphous phase. The in-plane magnetization of Sm0.9Pr0.1Fex thin films increases with increase in the Fe content, and low values of the in-plane coercivity occur in the range of 1.62 ≤ x ≤ 2.28. The magnetostriction value of Sm0.9Pr0.1Fex thin films increases with increasing the Fe content when x ≤ 1.94 and decreases when x > 1.94. The in-plane magnetostriction of Sm1-xNdxFe1.9 thin films under low magnetic fields has been improved by the substitution of Nd for Sm when x = 0.2.

  16. Structural and magnetic properties of pulsed laser deposited Fe–SiC thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Mukesh [Nanoscience Laboratory, Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee, UK 247 667 (India); Chandra, Ramesh, E-mail: ramesfic@iitr.ac.in [Nanoscience Laboratory, Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee, UK 247 667 (India); Goyat, Manjeet S. [University of Petroleum & Energy Studies, Dehradun, Uttarakhand 248007 (India); Mishra, Raghwesh; Tiwari, Rajesh K.; Saxena, A.K. [Applied Chemistry Division, Defence Materials & Stores Research & Development Establishment (DMSRDE), GT Road, Kanpur, UP 208013 (India)

    2015-03-31

    Structural and magnetic properties of Fe–SiC thin films have been studied. The Fe–SiC thin films were fabricated by pulsed laser deposition on Si (100) substrate and isochronally annealed at 1073 K and 1273 K in argon atmosphere for 2.5 h. The crystalline ordering of SiC into β-SiC phase and growths of other phases like Fe{sub 3}Si, SiO{sub 2} and FeSiO{sub 3} during annealing were investigated by X-ray diffraction and X-ray photoelectron spectroscopy measurements. The morphology of thin films was changed from voided structure to dense pyramidal-like structure due to annealing. A continuous decrease in the saturation magnetization and non-monotonic change in coercivity of Fe–SiC thin films were observed with increase in annealing temperature. - Highlights: • Structural and magnetic properties of Fe–SiC thin films have been studied. • Crystalline ordering of SiC into β-SiC phase was obtained at T ≥ 800 °C. • Annealed Fe–SiC thin films show ferromagnetic hysteresis at room temperature. • Coercivity was found to be dependent on the annealing temperature.

  17. Surface morphology and magnetic property of wrinkled FeGa thin films fabricated on elastic polydimethylsiloxane

    Science.gov (United States)

    Zhang, Shuanglan; Zhan, Qingfeng; Yu, Ying; Liu, Luping; Li, Huihui; Yang, Huali; Xie, Yali; Wang, Baomin; Xie, Shuhong; Li, Run-Wei

    2016-03-01

    We investigated the surface morphology and the magnetic property of wrinkled Fe81Ga19 (FeGa) thin films fabricated in two different processes onto elastic polydimethylsiloxane (PDMS) substrates. The films obtained by directly depositing Ta and FeGa layers on a pre-strained PDMS substrate display a sinusoidally wrinkled surface and a weak magnetic anisotropy. The wavelength and amplitude of the sinusoidal morphology linearly increase with the metallic layer thickness, while the magnetic anisotropy decreases with increasing FeGa thickness. The other films grown by depositing FeGa layer on a wrinkled Ta/PDMS surface show a remarkable uniaxial magnetic anisotropy. The strength of magnetic anisotropy increases with increasing FeGa thickness. The magnetic anisotropy can be ascribed to the surface anisotropy, the magnetostrictive anisotropy, and the shape anisotropy caused, respectively, by the magnetic charges on wavy morphology, the residual mechanical stress, and the inhomogeneous thickness of FeGa films.

  18. On Magnetic Dynamos in Thin Accretion Disks around Compact and Young Stars

    Science.gov (United States)

    Stepinski, T. F.

    1993-01-01

    A variety of geometrically thin accretion disks commonly associated with such astronomical objects as X-ray binaries, cataclysmic variables, and protostars are likely to be seats of MHD dynamo actions. Thin disk geometry and the particular physical environment make accretion disk dynamos different from stellar, planetary, or even galactic dynamos. We discuss those particular features of disk dynamos with emphasis on the difference between protoplanetary disk dynamos and those associated with compact stars. We then describe normal mode solutions for thin disk dynamos and discuss implications for the dynamical behavior of dynamo-magnetized accretion disks.

  19. Fabrication and characteristics of magnetic field sensors based on nano-polysilicon thin-film transistors

    Institute of Scientific and Technical Information of China (English)

    Zhao Xiaofeng; Wen Dianzhong; Zhuang Cuicui; Cao Jingya; Wang Zhiqiang

    2013-01-01

    A magnetic field sensor based on nano-polysilicon thin films transistors (TFTs) with Hall probes is proposed.The magnetic field sensors are fabricated on 〈100〉 orientation high resistivity (ρ > 500 Ω·cm) silicon substrates by using CMOS technology,which adopt nano-polysilicon thin films with thicknesses of 90 nm and heterojunction interfaces between the nano-polysilicon thin films and the high resistivity silicon substrates as the sensing layers.The experimental results show that when VDS =5.0 V,the magnetic sensitivities of magnetic field sensors based on nano-polysilicon TFTs with length-width ratios of 160 μm/80 μm,320 μm/80 μm and 480 μm/80μm are 78 mV/T,55 mV/T and 34 mV/T,respectively.Under the same conditions,the magnetic sensitivity of the obtained magnetic field sensor is significantly improved in comparison with a Hall magnetic field sensor adopting silicon as the sensing layers.

  20. Modification of magnetic anisotropy induced by swift heavy ion irradiation in cobalt ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nongjai, Razia [Department of Applied Physics, Zakir Hussain College of Engineering & Technology, A.M.U., Aligarh 202002 (India); Khan, Shakeel, E-mail: skhanapad@gmail.com [Department of Applied Physics, Zakir Hussain College of Engineering & Technology, A.M.U., Aligarh 202002 (India); Ahmed, Hilal; Khan, Imran [Department of Applied Physics, Zakir Hussain College of Engineering & Technology, A.M.U., Aligarh 202002 (India); Annapoorni, S. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Gautam, Sanjeev [Advanced Analysis Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of); Lin, Hong-Ji; Chang, Fan-Hsiu [National Synchrotron Radiation Research Center (NSRRC), Hsinchu 30076, Taiwan (China); Hwa Chae, Keun [Advanced Analysis Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of); Asokan, K. [Material Science Division, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2015-11-15

    The present study demonstrates the modification of magnetic anisotropy in cobalt ferrite (CoFe{sub 2}O{sub 4}) thin films induced by swift heavy ion irradiations of 200 MeV Ag-ion beams. The study reveals that both magnetizations and coercive field are sensitive to Ag-ions irradiation and to the fluences. The magnetic anisotropy enhanced at low fluence of Ag-ions due to domain wall pinning at defect sites created by ion bombardment and at high fluence, this magnetic anisotropy ceases and changes to isotropic behavior which is explained based on the significant structural and morphological changes. An X-ray absorption and x-ray magnetic circular dichroism studies confirms the inverse spinel structure of these compounds. - Highlights: • CoFe{sub 2}O{sub 4} thin films have been deposited on Silicon substrate by pulsed laser deposition technique. • Swift heavy ion irradiation of thin films at three different fluences. • Studied the structural and magnetic properties of the samples. • XRD and Raman studies indicate strain in the films. • Observed perpendicular magnetic anisotropy.

  1. Reorientation of magnetic anisotropy in epitaxial cobalt ferrite thin films

    NARCIS (Netherlands)

    Lisfi, A.; Williams, C.M.; Nguyen, L.T.; Lodder, J.C.; Coleman, A.; Corcoran, H.; Johnson, A.; Chang, P.; Kumar, A.; Morgan, W.

    2007-01-01

    Spin reorientation has been observed in CoFe2O4 thin single crystalline films epitaxially grown on (100) MgO substrate upon varying the film thickness. The critical thickness for such a spin-reorientation transition was estimated to be 300 nm. The reorientation is driven by a structural transition

  2. Reorientation of magnetic anisotropy in epitaxial cobalt ferrite thin films

    NARCIS (Netherlands)

    Lisfi, A.; Williams, C.M.; Nguyen, L.T.; Lodder, J.C.; Coleman, A.; Corcoran, H.; Johnson, A.; Chang, P.; Abhishek Kumar, A.K.; Kumar, A.; Morgan, W.

    2007-01-01

    Spin reorientation has been observed in CoFe2O4 thin single crystalline films epitaxially grown on (100) MgO substrate upon varying the film thickness. The critical thickness for such a spin-reorientation transition was estimated to be 300 nm. The reorientation is driven by a structural transition

  3. Magnetic ordering in nickel-zinc nanoferrite thin film formed by Langmuir Blodgett technique

    Science.gov (United States)

    Thakur, Sangeeta; Pandit, Pallavi; Sharma, S. K.; Katyal, S. C.; Singh, Mahavir; Gupta, Ajay

    2013-12-01

    Nickel-zinc nanoferrite thin films, which reveal application for magnetic materials, were prepared by Langmuir-Blodgett technique. X-ray reflectivity fitting was done using three layer model. Thickness of a monolayer of nanoparticles is obtained as 23.5 Å. Surface roughness increases as the thickness of the film increases. Fourier transform infrared spectra confirmed that the structure remains cubic spinel after thin film formation. We have measured zero-field cooled and field cooled magnetization and discussed the behavior in three parts: the ferromagnetic part, transition region, and the superparamagnetic part.

  4. Perpendicular Magnetic Anisotropy in Co-Based Full Heusler Alloy Thin Films

    Science.gov (United States)

    Wu, Y.; Xu, X. G.; Miao, J.; Jiang, Y.

    2015-12-01

    Half-metallic Co-based full Heusler alloys have been qualified as promising functional materials in spintronic devices due to their high spin polarization. The lack of perpendicular magnetic anisotropy (PMA) is one of the biggest obstacles restricting their application in next generation ultrahigh density storage such as magnetic random access memory (MARM). How to induce the PMA in Co-based full Heusler alloy thin films has attracted much research interest of scientists. This paper presents an overview of recent progress in this research area. We hope that this paper would provide some guidance and ideas to develop highly spin-polarized Co-based Heusler alloy thin films with PMA.

  5. The magnetic properties and microstructure of Co-Pt thin films using wet etching process.

    Science.gov (United States)

    Lee, Chang-Hyoung; Cho, Young-Lae; Lee, Won-Pyo; Suh, Su-Jeong

    2014-11-01

    Perpendicular magnetic recording (PMR) is a promising candidate for high density magnetic recording and has already been applied to hard disk drive (HDD) systems. However, media noise still limits the recording density. To reduce the media noise and achieve a high signal-to-noise ratio (SNR) in hard disk media, the grains of the magnetic layer must be magnetically isolated from each other. This study examined whether sputter-deposited Co-Pt thin films can have adjacent grains that are physically isolated. To accomplish this, the effects of the sputtering conditions and wet etching process on magnetic properties and the microstructure of the films were investigated. The film structure was Co-Pt (30 nm)/Ru (30 nm)/NiFe (10 nm)/Ta (5 nm). The composition of the Co-Pt thin films was Co-30.7 at.% Pt. The Co-Pt thin films were deposited in Ar gas at 5, 10, 12.5, and 15 mTorr. Wet etching process was performed using 7% nitric acid solution at room temperature. These films had high out-of-plane coercivity of up to 7032 Oe, which is twice that of the as-deposited film. These results suggest that wet etched Co-Pt thin films have weaker exchange coupling and enhanced out-of-plane coercivity, which would reduce the medium noise.

  6. Determination of hepatitis B surface antigen using magnetic immunoassays in a thin channel.

    Science.gov (United States)

    Tsai, H Y; Chan, J R; Li, Y C; Cheng, F C; Fuh, C Bor

    2010-08-15

    We report novel methods for detection of hepatitis B surface antigen (HBsAg) based on competitive and sandwiched magnetic immunoassays using functional magnetic nanoparticles in a thin channel. Magnetic nanoparticles labeled with hepatitis B antibody are flowed through a thin channel to form a predeposition layer for capturing HBsAg. Competitive and sandwiched magnetic immunoassays were studied and detection limit, linear range, and sample selectivity were compared. The detection limits of competitive and sandwiched magnetic immunoassays were found to be 0.26 and 0.25 pg/ml, respectively. The linear range of HBsAg concentration was 0.26 pg/ml-2.6 ng/ml for competitive magnetic immunoassay and was 0.89 pg/ml-8.9 ng/ml for sandwiched magnetic immunoassay. The advantages of these methods over ELISA and other methods for HBsAg detection are lower detection limits and wider linear ranges. The running time was less than 30 min. Competitive magnetic immunoassay was faster than sandwiched magnetic immunoassay for detection of HBsAg. The measurements of HBsAg in serum samples from these methods differed by about 10% from those of ELISA. These methods can provide simple, fast, and sensitive detections of biomarkers and other immunoassay-related samples.

  7. ULSE-MAGNETIC STAMPING OF THIN-WALLED CYLINDRICAL DYES

    Directory of Open Access Journals (Sweden)

    S. Bondar

    2009-01-01

    Full Text Available The design of pulse magnetic stamping technological operation is considered in the given article. The stress state of die – slug system is analyzed. Recommendations concerning the technological equipment condition are given.

  8. Gracing incidence small angle neutron scattering of incommensurate magnetic structures in MnSi thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wiedemann, Birgit; Pfleiderer, Christian; Boeni, Peter [Physik Department, Technische Universitaet Muenchen (Germany); Zhang, Shilei; Hesjedal, Thorsten [Clarendon Laboratory, Department of Physics, University of Oxford (United Kingdom); Khaydukov, Yury; Soltwedel, Olaf; Keller, Thomas [Max-Planck-Institut fuer Festkoerperforschung (Germany); Max Planck Society, Outstation at FRM-II (Germany); Muehlbauer, Sebastian [Forschungsneutronenquelle Heinz Maier Leibnitz, Technische Universitaet Muenchen (Germany); Chacon, Alfonso [Physik Department, Technische Universitaet Muenchen (Germany); Forschungsneutronenquelle Heinz Maier Leibnitz, Technische Universitaet Muenchen (Germany)

    2015-07-01

    The topological stability of skyrmions in bulk samples of MnSi and the observation of spin transfer torque effects at ultra-low current densities have generated great interest in skyrmions in chiral magnets as a new route towards next generation spintronics devices. Yet, the formation of skyrmions in MBE grown thin films of MnSi reported in the literature is highly controversial. We report gracing incidence small angle neutron scattering (GISANS) of the magnetic order in selected thin films of MnSi grown by state of the art MBE techniques. In combination with polarised neutron reflectometry (PNR) and magnetisation measurements of the same samples our data provide direct reciprocal space information of the incommensurate magnetic order, clarifying the nature of magnetic phase diagram.

  9. Investigation of the magnetic properties of insulating thin films using the longitudinal spin Seebeck effect

    Energy Technology Data Exchange (ETDEWEB)

    Kehlberger, A., E-mail: kehlberg@uni-mainz.de; Jakob, G.; Kläui, M. [Institute of Physics, University of Mainz, 55099 Mainz (Germany); Onbasli, M. C.; Kim, D. H.; Ross, C. A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-05-07

    The longitudinal spin Seebeck effect is used as a detector for the magnetic properties and switching characteristics of magnetic thin insulating films. We use a 300 nm and a 20 nm thick Yttrium Iron Garnet (YIG, Y{sub 3}Fe{sub 5}O{sub 12}) film prepared by pulsed laser deposition and afterwards coated by platinum for the detection of the thermally excited magnons by the inverse spin Hall effect. The inverse spin Hall signals reveal a magnetic uniaxial anisotropy along the direction of the platinum stripe in the thicker film. For the thin film we find a more isotropic behavior, which is complementarily observed using the magnetoresistance occurring at the platinum/YIG interface. We explain our results on the basis of x-ray diffraction data, which reveal a miscut of the substrate and film surface and an expansion of the YIG lattice. Both findings favor a growth-induced magnetic anisotropy that we observe.

  10. Towards wafer scale inductive determination of magnetostatic and dynamic parameters of magnetic thin films and multilayers

    CERN Document Server

    Sievers, Sibylle; Nass, Paul; Serrano-Guisan, Santiago; Pasquale, Massimo; Schumacher, Hans Werner

    2013-01-01

    We investigate an inductive probe head suitable for non-invasive characterization of the magnetostatic and dynamic parameters of magnetic thin films and multilayers on the wafer scale. The probe is based on a planar waveguide with rearward high frequency connectors that can be brought in close contact to the wafer surface. Inductive characterization of the magnetic material is carried out by vector network analyzer ferromagnetic resonance. Analysis of the field dispersion of the resonance allows the determination of key material parameters such as the saturation magnetization MS or the effective damping parameter Meff. Three waveguide designs are tested. The broadband frequency response is characterized and the suitability for inductive determination of MS and Meff is compared. Integration of such probes in a wafer prober could in the future allow wafer scale in-line testing of magnetostatic and dynamic key material parameters of magnetic thin films and multilayers.

  11. Tuning of Transport and Magnetic Properties in Epitaxial LaMnO3+δ Thin Films

    Directory of Open Access Journals (Sweden)

    J. Chen

    2014-01-01

    Full Text Available The effect of compressive strain on the transport and magnetic properties of epitaxial LaMnO3+δ thin films has been investigated. It is found that the transport and magnetic properties of the LaMnO3+δ thin films grown on the LaAlO3 substrates can be tuned by the compressive strain through varying film thickness. And the insulator-metal transition, charge/orbital ordering transition, and paramagnetic-ferromagnetic transition are suppressed by the compressive strain. Consequently, the related electronic and magnetic transition temperatures decrease with an increase in the compressive strain. The present results can be explained by the strain-controlled lattice deformation and the consequent orbital occupation. It indicates that the lattice degree of freedom is crucial for understanding the transport and magnetic properties of the strongly correlated LaMnO3+δ.

  12. Perpendicular magnetic anisotropy in Mn2CoAl thin film

    Science.gov (United States)

    Sun, N. Y.; Zhang, Y. Q.; Fu, H. R.; Che, W. R.; You, C. Y.; Shan, R.

    2016-01-01

    Heusler compound Mn2CoAl (MCA) is attracting more attentions due to many novel properties, such as high resistance, semiconducting behavior and suggestion as a spin-gapless material with a low magnetic moment. In this work, Mn2CoAl epitaxial thin film was prepared on MgO(100) substrate by magnetron sputtering. The transport property of the film exhibits a semiconducting-like behavior. Moreover, our research reveals that perpendicular magnetic anisotropy (PMA) can be induced in very thin Mn2CoAl films resulting from Mn-O and Co-O bonding at Mn2CoAl/MgO interface, which coincides with a recent theoretical prediction. PMA and low saturation magnetic moment could lead to large spin-transfer torque with low current density in principle, and thus our work may bring some unanticipated Heusler compounds into spintronics topics such as the domain wall motion and the current-induced magnetization reversal.

  13. Thin films on the basis of magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    G. Alimbekova

    2012-09-01

    Full Text Available The present work is to study the adsorption of magnetic nanoparticles in the structure of nanohybrid films by layer-by-layer (LbL method. Obtained by UV-VIS absorption spectra of 5% magnetic nanoparticles and the aqueous solution polyvinyl alcohol consisting of 5 and 10 nanohybrid layers. Analysis of the optical absorption spectra shows the homogeneity and mechanical stability of the nanohybrid films.

  14. Co-containing spinel ferrite thin-film perpendicular magnetic recording media with Mn-Zn ferrite backlayer

    OpenAIRE

    Yamamoto, Setsuo; Kuniki, Hirofumi; Kurisu, Hiroki; Matsuura, Mitsuru

    2003-01-01

    Co-containing ferrite thin-film/Mn-Zn ferrite thin-film double-layered perpendicular media were prepared using reactive ECR sputtering and magnetron sputtering methods, and their magnetic and structural properties and recording characteristics were studied. The Mn-Zn ferrite thin-film backlayer had saturation magnetization of 3.5 kG and coercivity of 60 Oe. Reproduced voltage for the Co-containing ferrite thin-film/Mn-Zn ferrite thin-film double-layered medium was about twice of that for the ...

  15. Influence of Bath Composition on Magnetic Properties of Electrodeposited Co-Pt-W Thin Films

    Institute of Scientific and Technical Information of China (English)

    GE Hong-liang; WEI Guo-ying; WU Qiong; ZHOU Qiao-ying; WANG Xin-yan

    2007-01-01

    Effect of bath composition ([Co2+]/[PtⅣ] and [WO2-4], [cit-]) and pH on the magnetic properties of electrodeposited Co-Pt-W thin films has been investigated. Electrodeposited Co-Pt-W thin films exhibited strong perpendicular magnetic anisotropy when the ratio of [Co2+] to [PtⅣ] was 10; cathode current efficiency and perpendicular magnetic anisotropy showed little variations when [WO2-4] was lower than 0.1 mol/L, but perpendicular magnetic anisotropy had strengthened when [WO2-4] was over 0.1 mol/L, which could be explained by the fact that the hydrogen evolution could produce pores as magnetic domain pinnings; citrate as complexing reagent can promote the polarization of [Co2+] and [PtⅣ]. As a result, the equilibrium electrode potentials of cobalt and platinum moved to negative direction, which led to the co-deposition of Co, Pt, and W. It was also found out that the as-deposited Co-Pt-W hard magnetic thin films were very homogeneous, smooth, and had the maximum coercivity for the bath pH 8.5 and the concentration of citrate 0.26 mol/L.

  16. Thin magnetic conductor substrate for placement-immune, electrically-small antennas.

    Energy Technology Data Exchange (ETDEWEB)

    Eubanks, Travis Wayne; McDonald, Jacob J.; Loui, Hung

    2011-09-01

    An antenna is considered to be placement-immune when the antenna operates effectively regardless of where it is placed. By building antennas on magnetic conductor materials, the radiated fields will be positively reinforced in the desired radiation direction instead of being negatively affected by the environment. Although this idea has been discussed thoroughly in theoretical research, the difficulty in building thin magnetic conductor materials necessary for in-phase field reflections prevents this technology from becoming more widespread. This project's purpose is to build and measure an electrically-small antenna on a new type of non-metallic, thin magnetic conductor. This problem has not been previously addressed because non-metallic, thin magnetic conductor materials have not yet been discovered. This work proposed the creation of an artificial magnetic conductor (AMC) with in-phase field reflections without using internal electric conductors, the placement of an electrically-small antenna on this magnetic conductor, and the development of a transmit-receive system that utilizes the substrate and electrically-small antenna. By not using internal electric conductors to create the AMC, the substrate thickness can be minimized. The electrically-small antenna will demonstrate the substrate's ability to make an antenna placement immune, and the transmit-receive system combines both the antenna and the substrate while adding a third layer of system complexity to demonstrate the complete idea.

  17. Correlating properties and microstructure of YBCO thin films by magnetic X-ray microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ruoss, Stephen; Stahl, Claudia; Weigand, Markus; Schuetz, Gisela [Max-Planck-Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Zahn, Patrick; Bayer, Jonas [Max-Planck-Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Research Institute for Innovative Surfaces, FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany); Albrecht, Joachim [Research Institute for Innovative Surfaces, FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany)

    2016-07-01

    The magnetic flux distribution in high-temperature superconductors namely YBCO has been observed using a novel high-resolution technique based on the X-ray magnetic circular dichroism (XMCD). Therefore, a CoFeB layer is deposited on the superconductor which exhibits a strong XMCD-effect. X-ray absorption measurements with circular polarized radiation allows the analysis of the magnetic flux distribution in the superconductor via the soft-magnetic sensor layer [3,4]. In the total electron yield (TEY) mode of the scanning X-ray microscope (SXM) the surface structure and the magnetic domains can be imaged at the same time. Having obtained such high resolution images, the correlation of magnetic flux penetration and defect structure of YBCO thin films can be analyzed. The measurements have been performed at the scanning X-ray microscope MAXYMUS at Bessy II, HZB Berlin.

  18. Tuning the properties of magnetic thin films by interaction with periodic nanostructures

    Directory of Open Access Journals (Sweden)

    Ulf Wiedwald

    2012-12-01

    Full Text Available The most important limitation for a significant increase of the areal storage density in magnetic recording is the superparamagnetic effect. Below a critical grain size of the used CoCrPt exchange-decoupled granular films the information cannot be stored for a reasonable time (typically ten years due to thermal fluctuations arbitrary flipping of the magnetization direction. An alternative approach that may provide higher storage densities is the use of so-called percolated media, in which defect structures are imprinted in an exchange-coupled magnetic film. Such percolated magnetic films are investigated in the present work. We employ preparation routes that are based on (i self-assembly of Au nanoparticles and (ii homogeneous size-reduction of self-assembled polystyrene particles. On such non-close-packed nanostructures thin Fe films or Co/Pt multilayers are grown with in-plane and out-of-plane easy axis of magnetization. The impact of the particles on the magnetic switching behavior is measured by both integral magnetometry and magnetic microscopy techniques. We observe enhanced coercive fields while the switching field distribution is broadened compared to thin-film reference samples. It appears possible to tailor the magnetic domain sizes down to the width of an unperturbed domain wall in a continuous film, and moreover, we observe pinning and nucleation at or close to the imprinted defect structures.

  19. Generation of dynamo magnetic fields in thin Keplerian disks

    Science.gov (United States)

    Stepinski, T. F.; Levy, E. H.

    1990-01-01

    The combined action of nonuniform rotation and helical convection in protoplanetary disks, in the Galaxy, or in accretion disks surrounding black holes and other compact objects, enables an alpha-omega dynamo to generate a large-scale magnetic field. In this paper, the properties of such magnetic fields are investigated using a two-dimensional, partially numerical method. The structures of the lowest-order steady state and oscillatory modes are calculated for two kinds of external boundary conditions. A quadruple, steady state, highly localized mode is the most easily excited for low values of the dynamo number. The results indicate that, except under special conditions, disk dynamo modes tend to consist of relatively localized rings structures. For large values of the dynamo number, the magnetic field consists of a number of quasi-independent, spatially localized modes generated in various concentric rings filling the disk inward of a dynamo generation 'front'.

  20. Generation of dynamo magnetic fields in thin Keplerian disks

    Energy Technology Data Exchange (ETDEWEB)

    Stepinski, T.F.; Levy, E.H. (Arizona Univ., Tucson (USA))

    1990-10-01

    The combined action of nonuniform rotation and helical convection in protoplanetary disks, in the Galaxy, or in accretion disks surrounding black holes and other compact objects, enables an alpha-omega dynamo to generate a large-scale magnetic field. In this paper, the properties of such magnetic fields are investigated using a two-dimensional, partially numerical method. The structures of the lowest-order steady state and oscillatory modes are calculated for two kinds of external boundary conditions. A quadruple, steady state, highly localized mode is the most easily excited for low values of the dynamo number. The results indicate that, except under special conditions, disk dynamo modes tend to consist of relatively localized rings structures. For large values of the dynamo number, the magnetic field consists of a number of quasi-independent, spatially localized modes generated in various concentric rings filling the disk inward of a dynamo generation front. 36 refs.

  1. Magnetic properties of electroplated nano/microgranular NiFe thin films for rf application

    NARCIS (Netherlands)

    Zhuang, Y.; Vroubel, M.; Rejaei, B.; Burghartz, J.N.; Attenborough, K.

    2005-01-01

    A granular NiFe thin film with large in-plane magnetic anisotropy and high ferromagnetic-resonance frequency developed for radio-frequency integrated circuit (IC) applications is presented. During the deposition, three-dimensional (3D) growth occurs, yielding NiFe grains (ϕ ∼ 1.0 μm). Nanonuclei (ϕ

  2. Effects of Toroidal Magnetic Fields on the Thermal Instability of Thin Accretion Disks

    Indian Academy of Sciences (India)

    Sheng-Ming Zheng; Feng Yuan; Wei-Min Gu; Ju-Fu Lu

    2011-03-01

    The standard thin disk model predicts that when the accretion rate is moderately high, the disk is radiation–pressure-dominated and thermally unstable. However, observations indicate the opposite, namely the disk is quite stable. We present an explanation in this work by taking into account the role of the magnetic field which was ignored in the previous analysis.

  3. Computer simulation of a magnetic thin film of CoCr

    NARCIS (Netherlands)

    Reuvekamp, E.M.C.M.; Opheusden, van J.H.J.; Gerritsma, G.J.

    1990-01-01

    A discrete micromagnetic model for a thin magnetic layer has been developed to perform computer simulations. The magnetisation in this model is given in terms of a cubic array of interacting microscopic spins. The dynamics of the spins is given by both a time discretisation of the Landau-Lifshitz-Gi

  4. Planar Hall effect and magnetic anisotropy in epitaxially strained chromium dioxide thin films

    NARCIS (Netherlands)

    Goennenwein, S.T.B.; Keizer, R.S.; Schink, S.W.; Van Dijk, I.; Klapwijk, T.M.; Miao, G.X.; Xiao, G.; Gupta, A.

    2007-01-01

    We have measured the in-plane anisotropic magnetoresistance of 100 nm thick CrO2 thin films at liquid He temperatures. In low magnetic fields H, both the longitudinal and the transverse (planar Hall) resistance show abrupt switches, which characteristically depend on the orientation of H. All the ex

  5. Output characteristics of a thin-film piezoelectric AE sensor for magnetic head-disk interaction

    NARCIS (Netherlands)

    Imai, S.; Burger, G.J.; Lammerink, T.S.J.; Fluitman, J.H.J.

    1997-01-01

    A new type of acoustic emission (AE) sensor was developed for detecting head disk interaction in magnetic disk devices. In order to develop a small sensor, we used a thin-film piezoelectric material and mounted it on the Si slider using micromachining techniques. We conducted a basic experiment and

  6. Output characteristics of a thin-film piezoelectric AE sensor for magnetic head-disk interaction

    NARCIS (Netherlands)

    Imai, Satomitsu; Burger, Gert-Jan; Lammerink, Theo S.J.; Fluitman, Jan H.J.

    1996-01-01

    A new type of acoustic emission (AE) sensor was developed for detecting head-disk interaction in magnetic disk devices. In order to develop a small sensor, we used a thin-film piezoelectric material and mounted it on the Si slider using micromachining techniques. We conducted a basic experiment and

  7. Structural and magnetic characterization of very thin Co-Cr film

    NARCIS (Netherlands)

    Berge, ten Peter; Lodder, Cock; Porthun, Steffen; Popma, Theo

    1992-01-01

    In this paper we describe the nucleation and growth of thin Co---Cr layers on different substrates and seedlayers. Especially the presence and formation of the initial layer is considered, and corresponding growth mechanisms are proposed. The magnetic properties of these layers have been analyzed by

  8. Phenomenology of current-skyrmion interactions in thin films with perpendicular magnetic anisotropy

    NARCIS (Netherlands)

    Knoester, M. E.; Sinova, Jairo; Duine, R. A.

    2014-01-01

    We study skyrmions in magnetic thin films with structural inversion asymmetry perpendicular to the film plane. We construct a phenomenological model that describes the interaction between the motion of skyrmions and electric currents to lowest order in spin-orbit coupling. Based on this model, we es

  9. Phosphorus-doped thin silica films characterized by magic-angle spinning nuclear magnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Jacobsen, H.J.; Skibsted, J.; Kristensen, Martin

    2001-01-01

    Magic-angle spinning nuclear magnetic resonance spectra of 31P and 29Si have been achieved for a thin silica film doped with only 1.8% 31P and deposited by plasma enhanced chemical vapor deposition on a pure silicon wafer. The observation of a symmetric 31P chemical shift tensor is consistent...

  10. Obliquely co-evaporated thin films for magnetic recording

    NARCIS (Netherlands)

    Kranenburg, van Herma

    1992-01-01

    A systematic research is carried out on obliquely ( co- ) evaporated media for magnetic recording applications. The investigated materials concern Co-alloys, being Co-Cr, Co-Ag and Co- Ta. The re1ations between deposition parameters, morphology , texture and rnagnetic behaviour were swdied. The acce

  11. Brillouin Light Scattering studies of magnetic thin films and multilayers

    CERN Document Server

    Pugh, P R T

    2000-01-01

    crystal films. The films were grown on GaAs substrates and the BLS data gathered was analysed using derived expressions containing cubic and uniaxial anisotropy terms, the latter being derived here from first principals. 3. A series of FeCo alloy films deposited to thicknesses ranging from 46 A to 1000 A. The parameter of interest was the sample thickness below which the sample magnetization was found to be less that that of the bulk material. The BLS results were analysed using the Damon and Eshbach Surface mode expression. 4. The magnetic properties of an Fe/Cr trilayer wedge as a function of interlayer (Cr) spacer thickness. The transition from Antiferromagnetic to Ferromagnetic coupling was observed as function of Cr spacer thickness. BLS measurements at low and high field were correlated with features of the magnetization curves. 5. A series of 3 Co/Pt multilayers as a function of applied field. The results have yielded magnetization values for the films that are much lower than those of bulk Co. This wa...

  12. Barnett effect in thin magnetic films and nanostructures

    NARCIS (Netherlands)

    Bretzel, S.; Bauer, G.E.W.; Tserkovnyak, Y.; Brataas, A.

    2009-01-01

    The Barnett effect refers to the magnetization induced by rotation of a demagnetized ferromagnet. We describe the location and stability of stationary states in rotating nanostructures using the Landau–Lifshitz–Gilbert equation. The conditions for an experimental observation of the Barnett effect in

  13. Patterned magnetic thin films for ultra high density recording

    NARCIS (Netherlands)

    Lodder, J.C.; Haast, M.A.M.; Abelmann, L.; Hadjipanayis, G.C.

    2001-01-01

    The areal bit density of magnetic disk recording has increased since 1990 60% per year and even in the last years 100%. Extrapolation of these rates leads to recording parameters not likely to be achieved without changes in the present way of storing hard disk data. One of the possible solutions is

  14. Structure and magnetization in CoPd thin films and nanocontacts

    Science.gov (United States)

    Morgan, Caitlin; Schmalbuch, Klaus; García-Sánchez, Felipe; Schneider, Claus M.; Meyer, Carola

    2013-01-01

    We present results showing the structural and magnetic properties of MBE-grown extended films and nanostructured elements of various CoPd alloys. X-ray diffraction studies show that the thin films are polycrystalline, yet exhibit a strong preferential growth orientation along the (111) direction. Magnetic force microscopy and SQUID are used to gain an understanding of the magnetic behavior of the CoPd system with respect to competing anisotropy contributions, based on temperature-dependent SQUID data, collected between 4 and 300 K. The idea and potential implications of using CoPd as a contact material to achieve spin injection in carbon nanotube-based devices is discussed.

  15. Influence of electrostatic charging on the magnetic and other physical properties of thin metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Steinbeck, K.

    1971-01-01

    Electrical, superconducting and optical properties of thin metal films can be influenced by electrostatic charging. In the same way attempts have been made to change the saturation magnetization of ferromagnetic films, which was measured, e.g., with the torque method. Using the film as one plate of a capacitor torque changes are measured for different voltages. The torque changes are assumed to be caused by magnetization changes due to an altered electron concentration of the metal. The contribution of one unit charge to the magnetic moment was estimated to ca. /sup 1///sub 2/ mu/sub B/.

  16. Excellent soft magnetic properties realized in FeCoN thin films

    Institute of Scientific and Technical Information of China (English)

    Zhang Lu-Ran; Lü Hua; Liu Xi; Bai Jian-Min; Wei Fu-Lin

    2012-01-01

    FeCoN soft magnetic thin films are prepared by using the reactive direct-current magnetron sputtering technique.It is found that the addition of N2 can reduce the coercivity of the FeCoN film,and excellent soft magnetic properties can be obtained when the ratio of N2 flow to total gas flow is 10%.The influences of texture,grain size,and stress on the magnetic properties and the high-frequency behaviors of the films are also discussed.

  17. Thin film limits for Ginzburg--Landau with strong applied magnetic fields

    CERN Document Server

    Alama, Stan; Galvão-Sousa, Bernardo

    2009-01-01

    In this work, we study thin-film limits of the full three-dimensional Ginzburg-Landau model for a superconductor in an applied magnetic field oriented obliquely to the film surface. We obtain Gamma-convergence results in several regimes, determined by the asymptotic ratio between the magnitude of the parallel applied magnetic field and the thickness of the film. Depending on the regime, we show that there may be a decrease in the density of Cooper pairs. We also show that in the case of variable thickness of the film, its geometry will affect the effective applied magnetic field, thus influencing the position of vortices.

  18. Magnetic property and recording performance of chemical deposition CoP thin films

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The thickness of CoP thin films prepared by wet chemical deposition is of crucial importance on magnetic property and recording perform-ance. The coercivity of CoP films decreased with increasing film thickness. The coercivity was 45.37 kA m 1 at the thickness of 300 nm, and decreased to 21.65 kA m 1 at 5.7 μm. Recording performance tests indicate that, for drums with the same size, different recorded magnetic pole density have different thickness requirements. For 40 mm diameter magnetic drum, the optimal ...

  19. Magnetism in heterogeneous thin film systems: Resonant x-ray scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, J.B.; Jiang, J.S.; Bader, S.D.; Hellwig, O.; Marguiles, D.T.; Fullerton, E.E.

    2002-10-28

    Magnetic and chemical heterogeneity are common in a broad range of magnetic thin film systems. Emerging resonant soft x-ray scattering techniques are well suited to resolve such heterogeneity at relevant length scales. Resonant x-ray magneto-optical Kerr effect measurements laterally average over heterogeneity but can provide depth resolution in different ways, as illustrated in measurements resolving reversible and irreversible changes in different layers of exchange-spring heterostructures. Resonant small-angle scattering measures in-plane heterogeneity and can resolve magnetic and chemical scattering sources in different ways, as illustrated in measurements of granular alloy recording media.

  20. Magnetic and structural properties of thin films and nanoparticles studied by scattering methods

    OpenAIRE

    Feygenson, M.

    2007-01-01

    The present work concerns the magnetic and structural proprieties of magnetic thin films and magnetic nanoparticles studied by scattering methods.The structural properties of epitaxially grown Fe/Cr/Fe trilayer were studied with anomalous x-ray scattering. Two different x-ray energies have been used; (i) one E$_1$=5985eV to match the maximum contrast of the Fe/Cr interface close to the Cr absorption K-edge and (ii) a second one E$_2$=6940eV where the Fe/Cr interface displays the lowest contra...

  1. Magnetic anisotropy of thin sputtered MgB2 films on MgO substrates in high magnetic fields

    Directory of Open Access Journals (Sweden)

    Savio Fabretti

    2014-03-01

    Full Text Available We investigated the magnetic anisotropy ratio of thin sputtered polycrystalline MgB2 films on MgO substrates. Using high magnetic field measurements, we estimated an anisotropy ratio of 1.35 for T = 0 K with an upper critical field of 31.74 T in the parallel case and 23.5 T in the perpendicular case. Direct measurements of a magnetic-field sweep at 4.2 K show a linear behavior, confirmed by a linear fit for magnetic fields perpendicular to the film plane. Furthermore, we observed a change of up to 12% of the anisotropy ratio in dependence of the film thickness.

  2. Effect of high magnetic field on structure and magnetic properties of evaporated crystalline and amorphous Fe-Sm thin films

    Science.gov (United States)

    Li, Guojian; Li, Mengmeng; Wang, Jianhao; Du, Jiaojiao; Wang, Kai; Wang, Qiang

    2017-02-01

    Crystalline and amorphous Fe-Sm thin films have been fabricated by using molecular beam vapor deposition method. Then, the effects of both variation of Sm content and application of high magnetic field during film growth on the structure and magnetic properties of the Fe-Sm films have been explored. The results show that bcc structure of the Fe-Sm films with 5.8% Sm transforms to amorphization with 33.0% Sm. Meanwhile, nanocrystallite is formed in the amorphous Fe-Sm films. However, no Fe-Sm compound exists with the change of Sm content and with the application of high magnetic field. Nevertheless, high magnetic field decreases interplanar spacing. The structural evolution has a significant effect on magnetic properties. Saturation magnetization decreases 290% from 1456 emu/cm3 to 373 emu/cm3 with the increase of Sm content from 5.8% to 33.0%. The coercivity increases 1225% from 20 Oe to 265 Oe. Meanwhile, both the saturation magnetization and coercivity of the films decrease with the application of high magnetic field. The reason has been discussed.

  3. Patterning of magnetic thin films and multilayers using nanostructured tantalum gettering templates.

    Science.gov (United States)

    Qiu, Wenlan; Chang, Long; Lee, Dahye; Dannangoda, Chamath; Martirosyan, Karen; Litvinov, Dmitri

    2015-03-25

    This work demonstrates that a nonmagnetic thin film of cobalt oxide (CoO) sandwiched between Ta seed and capping layers can be effectively reduced to a magnetic cobalt thin film by annealing at 200 °C, whereas CoO does not exhibit ferromagnetic properties at room temperature and is stable at up to ∼400 °C. The CoO reduction is attributed to the thermodynamically driven gettering of oxygen by tantalum, similar to the exothermic reduction-oxidation reaction observed in thermite systems. Similarly, annealing at 200 °C of a nonmagnetic [CoO/Pd]N multilayer thin film sandwiched between Ta seed and Ta capping layers results in the conversion into a magnetic [Co/Pd]N multilayer, a material with perpendicular magnetic anisotropy that is of interest for magnetic data storage applications. A nanopatterning approach is introduced where [CoO/Pd]N multilayers is locally reduced into [Co/Pd]N multilayers to achieve perpendicular magnetic anisotropy nanostructured array. This technique can potentially be adapted to nanoscale patterning of other systems for which thermodynamically favorable combination of oxide and gettering layers can be identified.

  4. Phase formation, thermal stability and magnetic moment of cobalt nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Rachana [Institute of Engineering and Technology DAVV, Khandwa Road, Indore 452 017 (India); Pandey, Nidhi; Tayal, Akhil; Gupta, Mukul, E-mail: mgupta@csr.res.in, E-mail: dr.mukul.gupta@gmail.com [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001 (India)

    2015-09-15

    Cobalt nitride (Co-N) thin films prepared using a reactive magnetron sputtering process are studied in this work. During the thin film deposition process, the relative nitrogen gas flow (R{sub N{sub 2}}) was varied. As R{sub N{sub 2}} increases, Co(N), Co{sub 4}N, Co{sub 3}N and CoN phases are formed. An incremental increase in R{sub N{sub 2}}, after emergence of Co{sub 4}N phase at R{sub N{sub 2}} = 10%, results in a linear increase of the lattice constant (a) of Co{sub 4}N. For R{sub N{sub 2}} = 30%, a maximizes and becomes comparable to its theoretical value. An expansion in a of Co{sub 4}N, results in an enhancement of the magnetic moment, to the extent that it becomes even larger than pure Co. Such larger than pure metal magnetic moment for tetra-metal nitrides (M{sub 4}N) have been theoretically predicted. Incorporation of N atoms in M{sub 4}N configuration results in an expansion of a (relative to pure metal) and enhances the itinerary of conduction band electrons leading to larger than pure metal magnetic moment for M{sub 4}N compounds. Though a higher (than pure Fe) magnetic moment for Fe{sub 4}N thin films has been evidenced experimentally, higher (than pure Co) magnetic moment is evidenced in this work.

  5. Fabrication of L1{sub 0}-MnAl perpendicularly magnetized thin films for perpendicular magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Hosoda, Masaki; Oogane, Mikihiko; Kubota, Miho; Saruyama, Haruaki; Iihama, Satoshi; Naganuma, Hiroshi; Ando, Yasuo [Department of Applied Physics, Graduate school of Engineering, Tohoku University, Aza-aoba 6-6-05, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Kubota, Takahide [WPI Advanced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan)

    2012-04-01

    Structural and magnetic properties of MnAl thin films with different composition, growth temperature, and post-annealing temperature were investigated. The optimum condition for fabrication of L1{sub 0}-MnAl perpendicularly magnetized thin film deposited on Cr-buffered MgO single crystal substrate was revealed. The results of x ray diffraction indicated that the MnAl films annealed at proper temperature had a (001)-orientation and L1{sub 0}-ordered structure. The L1{sub 0}-ordered films were perpendicularly magnetized and had a large perpendicular anisotropy. In addition, low surface roughness was achieved. For the optimized fabrication condition, the saturation magnetization M{sub s} of 600 emu/cm{sup 3} and perpendicular magnetic anisotropy K{sub u} of 1.0 x 10{sup 7} erg/cm{sup 3} was obtained using the Mn{sub 48}Al{sub 52} target at deposition temperature of 200 deg. C and post-annealing temperature of 450 deg. C.

  6. Frequency characterization of thin soft magnetic material layers used in spiral inductors

    Energy Technology Data Exchange (ETDEWEB)

    Kriga, Adoum; Allassem, Desire [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France); Soultan, Malloum [Universite de N' Djamena N' Djamena (Chad); Chatelon, Jean-Pierre; Siblini, Ali [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France); Allard, Bruno [Laboratoire Ampere INSA-Lyon 20, avenue Einstein 69621 Villeurbanne Cedex France (France); Rousseau, Jean Jacques, E-mail: rousseau@univ-st-etienne.fr [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France)

    2012-07-15

    The paper details the characterization of thin magnetic materials layers, particularly soft materials, with respect to their behaviour in frequency (from 10 MHz to 1 GHz). The proposed method is suitable for any soft but insulating magnetic material; Yttrium Iron Garnet (YIG) is used as an example. The principle is based on a comparison between simulations for different values of the permeability and measurement values versus frequency of planar inductor structures; an experimental validation is proposed as well. Thin magnetic material is first deposited on an alumina substrate using RF sputtering technique; a planar spiral winding of copper is then deposited on the magnetic material by the same technique. The effective permeability versus frequency is obtained by comparing two samples of spiral windings with and without magnetic material. Network analyser measurements on samples of various geometrical dimensions and of different thicknesses are necessary to determine the effective magnetic permeability; we have obtained a relative effective permeability of about 30 for seven turns spiral inductor of a 17 {mu}m YIG film. - Highlights: Black-Right-Pointing-Pointer A simple and original method is presented for the characterization of soft magnetic layer. Black-Right-Pointing-Pointer This is a non-destructive method based on standard equipment. Black-Right-Pointing-Pointer The principle is based on a comparison between simulations and measurement. Black-Right-Pointing-Pointer An experimental validation is proposed as well.

  7. Magnetism and Verwey transition in magnetite nanoparticles in thin polymer film

    Energy Technology Data Exchange (ETDEWEB)

    Nikiforov, V.N., E-mail: nvn@lt.phys.msu.ru [Faculty of Physics, M.V. Lomonosov Moscow State University, 117234 Moscow (Russian Federation); Koksharov, Yu.A.; Polyakov, S.N. [Faculty of Physics, M.V. Lomonosov Moscow State University, 117234 Moscow (Russian Federation); Malakho, A.P. [Department of Material Sciences, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Volkov, A.V.; Moskvina, M.A. [Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Khomutov, G.B. [Faculty of Physics, M.V. Lomonosov Moscow State University, 117234 Moscow (Russian Federation); Irkhin, V.Yu. [Institute of Physics Metals, Ekaterinburg (Russian Federation)

    2013-08-25

    Highlights: ► Structural properties of magnetite nanoparticles in polyvinyl-alcohol thin films are investigated. ► Magnetic properties were studied by static magnetometry techniques, especially near the Verwey transition. ► The data obtained are discussed on the basis of complex temperature behavior of magnetic anisotropy. ► The EPR spectra and static magnetization data demonstrated clear anomalies in the interval 130–200 K. -- Abstract: Magnetic and structural properties of magnetite nanoparticles stabilized in polyvinyl-alcohol thin films are investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) and static magnetometry techniques. The nanoparticles have well-defined crystallinity, and are superparamagnetic at room temperature. Their size distribution is characterized by the distinct log-normal law (with average diameters near 5–7 nm) and slight maximum near 70–80 nm. The EPR spectra and static magnetization data demonstrated pronounced anomalies in the interval between 130 K (corresponding to Verwey transition) and 200 K. The experimental data obtained can be understood on the basis of the half-metallic electronic structure, complex temperature behavior of the magnetic anisotropy, along with effects of “weak magnetic-electron” sublattice of the magnetite.

  8. Modified magnetic ground state in NiMn2O4 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nelson-Cheeseman, B. B.; Chopdekar, R. V.; Toney, M. F.; Arenholz, E.; Suzuki, Y.; Iwata, J.M.

    2010-08-03

    We demonstrate the stabilization of a magnetic ground state in epitaxial NiMn2O4 (NMO) thin films not observed in their bulk counterpart. Bulk NMO exhibits a magnetic transition from a paramagnetic phase to a collinear ferrimagnetic moment configuration below 110 K and to a canted moment configuration below 70 K. By contrast, as-grown NMO films exhibit a single magnetic transition at 60 K and annealed films exhibit the magnetic behavior found in bulk. Cation inversion and epitaxial strain are ruled out as possible causes for the new magnetic ground state in the as-grown films. However, a decrease in the octahedral Mn{sup 4+}:Mn{sup 3+} concentration is observed and likely disrupts the double exchange that produces the magnetic state at intermediate temperatures. X-ray magnetic circular dichroism and bulk magnetometry indicate a canted ferrimagnetic state in all samples at low temperature. Together these results suggest that the collinear ferrimagnetic state observed in bulk NMO at intermediate temperatures is suppressed in the as grown NMO thin films due to a decrease in octahedral Mn{sup 4+} while the canted moment ferrimagnetic ordering is preserved below 60 K.

  9. Modified Magnetic Ground State in Nimn (2) O (4) Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Nelson-Cheeseman, B.B.; Chopdekar, R.V.; Iwata, J.M.; Toney, M.F.; Arenholz, E.; Suzuki, Y.; /SLAC

    2012-08-23

    The authors demonstrate the stabilization of a magnetic ground state in epitaxial NiMn{sub 2}O{sub 4} (NMO) thin films not observed in their bulk counterpart. Bulk NMO exhibits a magnetic transition from a paramagnetic phase to a collinear ferrimagnetic moment configuration below 110 K and to a canted moment configuration below 70 K. By contrast, as-grown NMO films exhibit a single magnetic transition at 60 K and annealed films exhibit the magnetic behavior found in bulk. Cation inversion and epitaxial strain are ruled out as possible causes for the new magnetic ground state in the as-grown films. However, a decrease in the octahedral Mn{sup 4+}:Mn{sup 3+} concentration is observed and likely disrupts the double exchange that produces the magnetic state at intermediate temperatures. X-ray magnetic circular dichroism and bulk magnetometry indicate a canted ferrimagnetic state in all samples at low T. Together these results suggest that the collinear ferrimagnetic state observed in bulk NMO at intermediate temperatures is suppressed in the as grown NMO thin films due to a decrease in octahedral Mn{sup 4+}, while the canted moment ferrimagnetic ordering is preserved below 60 K.

  10. Magnetic and dielectric properties of YbMnO3 perovskite thin films

    Science.gov (United States)

    Rubi, D.; Venkatesan, Sriram; Kooi, B. J.; de Hosson, J. Th. M.; Palstra, T. T. M.; Noheda, B.

    2008-07-01

    Metastable manganite perovskites displaying the antiferromagnetic so-called E phase are predicted to be multiferroic. Due to the need of high pressures for the synthesis of this phase, this prediction has only been confirmed in bulk HoMnO3 . Here we report on the growth and characterization of YbMnO3 perovskite thin films grown under epitaxial strain. Highly oriented thin films, with thickness down to 30 nm, can be obtained showing magnetodielectric coupling and magnetic responses as those expected for the E phase. We observe that the magnetic properties depart from the bulk behavior only in the case of ultrathin films (d<30nm) , which display a glassy magnetic behavior. We show that strain effects alone cannot account for this difference and that the film morphology plays, instead, a crucial role.

  11. Low temperature magnetic imaging of strained multiferroic EuTiO3 thin films

    Science.gov (United States)

    Geng, Yanan; Wu, Weida; Freeland, J. W.; Ryan, P.; Kim, J. W.; Ke, X.; Schiffer, P.; Lee, J. H.; Schlom, D. G.; Fennie, C. J.

    2010-03-01

    It has been predicted that the competition between paraelectric antiferromagnetic state and ferroelectric ferromagnetic state in perovskite EuTiO3 can be tuned by epitaxial strain.footnotetextC.J. Fennie and K.M. Rabe, Phys. Rev. Lett. 97, 267602 (2006). Tensile-strained EuTiO3 thin films grown on DyScO3 (110) substrate by molecular-beam epitaxy are confirmed to be ferromagnetic at low temperature by magnetometry and magneto-capacitance. Here we present magnetic imaging of EuTiO3/DyScO3 thin film using low temperature magnetic force microscopy (LT-MFM). Temperature dependence of MFM contrast confirms the ferromagnetic ground state. The magnetic field dependence of MFM images will be discussed in conjunction with magnetometry and magneto-capacitance measurements.

  12. Temperature dependence of magnetic anisotropies in ultra-thin films

    CERN Document Server

    Hucht, A

    1999-01-01

    shown that in contrast to other works the temperature driven spin reorientation transition in the monolayer is discontinuous also in the simulations, whereas in general it is continuous for the bilayer. Consequently the molecular field theory and the Monte Carlo simulations agree qualitatively. Exemplary for thicker films the influence of an external magnetic field is investigated in the bilayer, furthermore the effective anisotropies K sub n (T) of the phenomenological Landau theory are calculated numerically for the microscopic model. Analytic expressions for the dependence of the anisotropies K sub n (T) on the parameters of the model are obtained by the means of perturbation theory, which lead to a deeper understanding of the spin reorientation transition. Accordingly to this the origin for the spin reorientation transition lies in the differing temperature dependence of the dipolar and spin-orbit parts of the K sub n (T). Additionally the magnetization in the surface of the film decreases more rapidly wi...

  13. Brownian motion of massive skyrmions in magnetic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com [Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago 9170124 (Chile); Núñez, Álvaro S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile)

    2014-12-15

    We report on the thermal effects on the motion of current-driven massive magnetic skyrmions. The reduced equation for the motion of skyrmion has the form of a stochastic generalized Thiele’s equation. We propose an ansatz for the magnetization texture of a non-rigid single skyrmion that depends linearly with the velocity. By using this ansatz it is found that the skyrmion mass tensor is closely related to intrinsic skyrmion parameters, such as Gilbert damping, skyrmion-charge and dissipative force. We have found an exact expression for the average drift velocity as well as the mean-square velocity of the skyrmion. The longitudinal and transverse mobility of skyrmions for small spin-velocity of electrons is also determined and found to be independent of the skyrmion mass.

  14. Nanostructure and magnetic properties of magnesium ferrite thin films deposited on glass substrate by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Arabi, H., E-mail: arabi-h@um.ac.ir [Magnetism and Superconducting Research Laboratory, Department of Physics, Faculty of Science, University of Birjand, Birjand (Iran, Islamic Republic of); Department of Physics, Faculty of Science, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Khalili Moghadam, N. [Magnetism and Superconducting Research Laboratory, Department of Physics, Faculty of Science, University of Birjand, Birjand (Iran, Islamic Republic of)

    2013-06-15

    The spinel MgFe{sub 2}O{sub 4} thin films were prepared on the glass substrates at T{sub S}=400 °C by the spray pyrolysis deposition method. Structural and magnetic properties of the calcinated thin films at different temperatures were also investigated. By changing the calcination temperature from 400 to 600 °C, the crystallite size increased from 10 to 15 nm and the crystallinity of the films improved slightly. Thickness of the films calcinated at 400 and 600 °C were 0.648 and 1.473 μm respectively. However, the surface morphology of the films did not change considerably. Magnetic measurements, when the applied magnetic field was in parallel and perpendicular directions, showed the isotropic magnetic nature of the prepared films and their magnetic properties increased with the increment of calcination temperature. The H{sub c} value of thin films calcinated at 400 °C was about 168 Oe. - Highlights: ► Thin films of MgFe{sub 2}O{sub 4} are prepared via spray pyrolysis. ► All of the MgFe{sub 2}O{sub 4} films have nanostructure and the special magnetic properties. ► The surface morphology of films in different calcination temperatures is similar. ► The H{sub c} values of our films are independent of the applied field direction. ► The M{sub s} values in the plan and perpendicular directions are not the same.

  15. Radiative properties of magnetic neutron stars with metallic surfaces and thin atmospheres

    CERN Document Server

    Potekhin, A Y; van Adelsberg, M; Werner, K

    2012-01-01

    The goal of this work is to develop a simple analytic description of the emission properties (spectrum and polarization) of the condensed, strongly magnetized surface of neutron stars. We have improved the method of van Adelsberg et al. (2005) (arXiv:astro-ph/0406001) for calculating the spectral properties of condensed magnetized surfaces. Using the improved method, we calculate the reflectivity of an iron surface at magnetic field strengths B \\sim (10^{12} - 10^{14}) G, with various inclinations of the magnetic field lines and radiation beam with respect to the surface and each other. We construct analytic expressions for the emissivity of this surface as functions of the photon energy, magnetic field strength, and the three angles that determine the geometry of the local problem. Using these expressions, we calculate X-ray spectra for neutron stars with condensed iron surfaces covered by thin partially ionized hydrogen atmospheres. We develop simple analytic descriptions of the intensity and polarization o...

  16. The magnetic mechanism of Zn0.93Co0.07O thin films

    Institute of Scientific and Technical Information of China (English)

    AU; ChakTong

    2009-01-01

    Zn0.93Co0.07O thin films infiltrated with nitrogen and aluminum were prepared by means of magneton sputtering. The structural and magnetic properties of the films were studied systematically. The materials were single phase (wurtzite structure) with surfaces showing signs of homogeneous growth. The films were ferromagnetic at room temperature, and magnetic domains could be clearly observed on the surfaces. In the case of Al infiltration, saturated magnetization increased with Al concentration increasing; whereas in the case of N infiltration, saturated magnetization decreased with the increase in N concentration. The results show that ferromagnetic interactions in Co-doped ZnO diluted magnetic semiconductor may be transferred by electrons.

  17. Field dependent magnetic anisotropy of Ga0.2Fe0.8 thin films

    Science.gov (United States)

    Resnick, Damon A.; McClure, A.; Kuster, C. M.; Rugheimer, P.; Idzerda, Y. U.

    2011-04-01

    Using longitudinal MOKE in combination with a variable strength rotating magnetic field, called the rotational MOKE (ROTMOKE) method, we show that the magnetic anisotropy for a Ga0.2Fe0.8 single crystal film with a thickness of 17 nm, grown on GaAs (001) with a thick ZnSe buffer layer, depends linearly on the strength of the applied magnetic field. The torque moment curves generated using ROTMOKE are well fit with a model that accounts for the uniaxial, cubic, or fourfold anisotropy, as well as additional terms with a linear dependence on the applied magnetic field. The uniaxial and cubic anisotropy fields, taken from both the hard and the easy axis scans, are seen to remain field independent. The field dependent terms are evidence of a large affect of the magnetostriction and its contribution to the effective magnetic anisotropy in GaxFe1-x thin films.

  18. Electric field effect on the magnetization process for a very thin Co60Fe40 film

    Science.gov (United States)

    Suzuki, K. Z.; Ranjbar, R.; Sugihara, A.; Kondo, Y.; Mizukami, S.

    2016-08-01

    The electric field effect on the magnetization process for a very thin Co60Fe40 film was studied. The magnetization process under the electric field was characterized using tunnel magnetoresistance curves measured in a fully-epitaxial (001)-oriented CoFe(1)/MgO/CoFe(3) (thickness in nanometers) magnetic tunnel junction, where both the CoFe electrodes are magnetized in- plane. The out-of-plane saturation field of the thinner CoFe electrode changed linearly by varying the applied voltage, and the field-induced change of saturation field was estimated to be -0.10 TV-1. This change in the saturation field is interpreted as the electric field induced change in a perpendicular magnetic anisotropy originating from the CoFe/MgO interface. The electric field effect efficiency was estimated to be about 200 fJV-1 m-1.

  19. Mechanical manipulation of magnetic domains in continuous and patterned magnetostrictive FeGa thin films

    Science.gov (United States)

    Alexander, Paris; Fackler, Sean; Takeuchi, Ichiro; Cumings, John

    2013-03-01

    The controlled and reversible switching of magnetic domains using static electric fields has been previously demonstrated via magneto-electric (ME) coupling in a multiferroic system [T. Brintlinger, Nano Lett. 10, 1219(2010)]. In these systems, enhanced magnetostriction allows for magnetic switching in response to an electrically induced deformation. Here we demonstrate the nature of magnetic switching using mechanical stress alone. Magnetostrictive iron-gallium (Fe70Ga30) thin films are deposited on flexible free-standing membranes, and patterned to square arrays. Using a mechanically manipulated tip a strain is directly applied to the film. We observe the resulting magnetization dynamics using Lorentz-force transmission electron microscopy (LTEM). The varied hysteretic behaviors under applied magnetic and strain fields will be presented for both continuous and patterned films. This work was supported by the NSF-MRSEC at the University of Maryland, DMR 0520471.

  20. Dynamo magnetic field modes in thin astrophysical disks - An adiabatic computational approximation

    Science.gov (United States)

    Stepinski, T. F.; Levy, E. H.

    1991-01-01

    An adiabatic approximation is applied to the calculation of turbulent MHD dynamo magnetic fields in thin disks. The adiabatic method is employed to investigate conditions under which magnetic fields generated by disk dynamos permeate the entire disk or are localized to restricted regions of a disk. Two specific cases of Keplerian disks are considered. In the first, magnetic field diffusion is assumed to be dominated by turbulent mixing leading to a dynamo number independent of distance from the center of the disk. In the second, the dynamo number is allowed to vary with distance from the disk's center. Localization of dynamo magnetic field structures is found to be a general feature of disk dynamos, except in the special case of stationary modes in dynamos with constant dynamo number. The implications for the dynamical behavior of dynamo magnetized accretion disks are discussed and the results of these exploratory calculations are examined in the context of the protosolar nebula and accretion disks around compact objects.

  1. Thin-Film Magnetic-Field-Response Fluid-Level Sensor for Non-Viscous Fluids

    Science.gov (United States)

    Woodard, Stanley E.; Shams, Qamar A.; Fox, Robert L.; Taylor, Bryant D.

    2008-01-01

    An innovative method has been developed for acquiring fluid-level measurements. This method eliminates the need for the fluid-level sensor to have a physical connection to a power source or to data acquisition equipment. The complete system consists of a lightweight, thin-film magnetic-field-response fluid-level sensor (see Figure 1) and a magnetic field response recorder that was described in Magnetic-Field-Response Measurement-Acquisition System (LAR-16908-1), NASA Tech Briefs, Vol. 30, No. 6 (June 2006), page 28. The sensor circuit is a capacitor connected to an inductor. The response recorder powers the sensor using a series of oscillating magnetic fields. Once electrically active, the sensor responds with its own harmonic magnetic field. The sensor will oscillate at its resonant electrical frequency, which is dependent upon the capacitance and inductance values of the circuit.

  2. Effect of defects, magnetocrystalline anisotropy, and shape anisotropy on magnetic structure of iron thin films by magnetic force microscopy

    Directory of Open Access Journals (Sweden)

    Ke Xu

    2017-05-01

    Full Text Available Microstructures of magnetic materials, including defects and crystallographic orientations, are known to strongly influence magnetic domain structures. Measurement techniques such as magnetic force microscopy (MFM thus allow study of correlations between microstructural and magnetic properties. The present work probes effects of anisotropy and artificial defects on the evolution of domain structure with applied field. Single crystal iron thin films on MgO substrates were milled by Focused Ion Beam (FIB to create different magnetically isolated squares and rectangles in [110] crystallographic orientations, having their easy axis 45° from the sample edge. To investigate domain wall response on encountering non-magnetic defects, a 150 nm diameter hole was created in the center of some samples. By simultaneously varying crystal orientation and shape, both magnetocrystalline anisotropy and shape anisotropy, as well as their interaction, could be studied. Shape anisotropy was found to be important primarily for the longer edge of rectangular samples, which exaggerated the FIB edge effects and provided nucleation sites for spike domains in non-easy axis oriented samples. Center holes acted as pinning sites for domain walls until large applied magnetic fields. The present studies are aimed at deepening the understanding of the propagation of different types of domain walls in the presence of defects and different crystal orientations.

  3. Influence of Magnetic Field on Electric Charge Transport in Holomiun Thin Films at Low Temperatures

    Directory of Open Access Journals (Sweden)

    Jan Dudas

    2005-01-01

    Full Text Available Holmium thin films were prepared by evaporation in ultrahigh vacuum (UHV and high precision electrical resistance measurements were performed on them as well as on holomium bulk sample in the wide temperature range from 4,2 K up to the room temperature. Electric charge transport is profoundly influenced by the magnetic structure at low temperatures and a "knee-like" resistance anomaly was observed near the transportation from paramagnetic state to basal-plane spiral structure in bulk with the Neel temperature TN=128,9 K and below ~ 122 K in thin Ho films in a thickness range from 98 nm to 215 nm. Unexpected resistance minimum at ~ 9 K and a slope´s charge of the R vs. T curve near ~ 170 K was observed in 215 nm thin film. Application of magnetic field parallel to the substrate and thin film plane for temperatures below ~ 150 K caused the decrease of resistence value with increasing magnetic flux density. Increasing suppression of the TN value up to ~ 5 K with increasing flux density value up to 5 T was observed in Ho films. 

  4. Principal parametric resonance of axially accelerating rectangular thin plate in magnetic field

    Institute of Scientific and Technical Information of China (English)

    胡宇达; 张金志

    2013-01-01

    Nonlinear parametric vibration and stability is investigated for an axially accelerating rectangular thin plate subjected to parametric excitations resulting from the axial time-varying tension and axial time-varying speed in the magnetic field. Consid-ering geometric nonlinearity, based on the expressions of total kinetic energy, potential energy, and electromagnetic force, the nonlinear magneto-elastic vibration equations of axially moving rectangular thin plate are derived by using the Hamilton principle. Based on displacement mode hypothesis, by using the Galerkin method, the nonlinear para-metric oscillation equation of the axially moving rectangular thin plate with four simply supported edges in the transverse magnetic field is obtained. The nonlinear principal parametric resonance amplitude-frequency equation is further derived by means of the multiple-scale method. The stability of the steady-state solution is also discussed, and the critical condition of stability is determined. As numerical examples for an axially moving rectangular thin plate, the influences of the detuning parameter, axial speed, axial tension, and magnetic induction intensity on the principal parametric resonance behavior are investigated.

  5. The structure and magnetic properties of Fe-N thin films

    Institute of Scientific and Technical Information of China (English)

    周剑平; 李丹; 顾有松; 常香荣; 赵春生; 李福燊; 乔利杰; 田中卓; 宋庆山; 方光旦

    2002-01-01

    200 nm Fe-N thin films deposited on glass substrates by RF sputtering were vacuum annealed at 250-350℃ under 12000 A/m magnetic field. Heat treatment was effective in improving the soft magnetic properties of the Fe-N film. When the nitrogen content was in the range of 5-7 at. %,the thin films consisted of α′ + α" after heat treatment and had excellent soft magnetic properties of 4πMs = 2.4 T, Hc < 80 A/m, μr = 1500 under 2-10 MHz. The properties of the films meet the needs of a write head material used in the dual element GMR/inductive heads. The fromation mechanism and lattice constants of the α′ phase in Fe-N thin film are different from Jack's results obtained from γ→α′transformation in bulk samples. The linear relationship between a, c and Ca'N for thin film was obtained asc = 2. 866+ 1.559Ca'N,a = 2.866 + 0.181Ca'N.``

  6. Perpendicular magnetic tunnel junction with thin CoFeB/Ta/Co/Pd/Co reference layer

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Huadong, E-mail: huadong@avalanche-technology.com; Malmhall, Roger; Wang, Zihui; Yen, Bing K; Zhang, Jing; Wang, Xiaobin; Zhou, Yuchen; Hao, Xiaojie; Jung, Dongha; Satoh, Kimihiro; Huai, Yiming [Avalanche Technology, 46600 Landing Parkway, Fremont, California 94538 (United States)

    2014-11-10

    Integration of high density spin transfer torque magnetoresistance random access memory requires a thin stack (less than 15 nm) of perpendicular magnetic tunnel junction (p-MTJ). We propose an innovative approach to solve this challenging problem by reducing the thickness and/or moment of the reference layer. A thin reference layer structure of CoFeB/Ta/Co/Pd/Co has 60% magnetic moment of the conventional thick structure including [Co/Pd] multilayers. We demonstrate that the perpendicular magnetization of the CoFeB/Ta/Co/Pd/Co structure can be realized by anti-ferromagnetically coupling to a pinned layer with strong perpendicular anisotropy via Ruderman-Kittel-Kasuya-Yosida exchange interaction. The pMTJ with thin CoFeB/Ta/Co/Pd/Co reference layer has a comparable TMR ratio (near 80%) as that with thick reference layer after annealing at 280 °C. The pMTJ with thin reference layer has a total thickness less than 15 nm, thereby significantly increasing the etching margin required for integration of high density pMTJ array on wafers with form factor of 300 mm and beyond.

  7. Thin chitosan films containing super-paramagnetic nanoparticles with contrasting capability in magnetic resonance imaging.

    Science.gov (United States)

    Farjadian, Fatemeh; Moradi, Sahar; Hosseini, Majid

    2017-03-01

    Magnetic nanoparticles have found application as MRI contrasting agents. Herein, chitosan thin films containing super-paramagnetic iron oxide nanoparticles (SPIONs) are evaluated in magnetic resonance imaging (MRI). To determine their contrasting capability, super-paramagnetic nanoparticles coated with citrate (SPIONs-cit) were synthesized. Then, chitosan thin films with different concentrations of SPIONs-cit were prepared and their MRI data (i.e., r 2 and r 2*) was evaluated in an aqueous medium. The synthesized SPIONs-cit and chitosan/SPIONs-cit films were characterized by FTIR, EDX, XRD as well as VSM with the morphology evaluated by SEM and AFM. The nanoparticle sizes and distribution confirmed well-defined nanoparticles and thin films formation along with high contrasting capability in MRI. Images revealed well-dispersed uniform nanoparticles, averaging 10 nm in size. SPIONs-cit's hydrodynamic size averaged 23 nm in diameter. The crystallinity obeyed a chitosan and SPIONs pattern. The in vitro cellular assay of thin films with a novel route was performed within Hek293 cell lines showing that thin films can be biocompatible.

  8. Magnetic shielding performance of superconducting YBCO thin film in a multilayer device structure

    Energy Technology Data Exchange (ETDEWEB)

    Uzun, Y., E-mail: uzunyigitcan@gmail.com; Avci, I.

    2014-12-15

    Highlights: • A multilayer structure was fabricated in the form of YBCO/STO/YBCO. • Bottom layer was used as a magnetic shield. • The top layer was patterned as a microbridge. • Magnetic shielding performance of the bottom layer onto the microbridge was tested. • I{sub c} of the microbridge was kept constant under the various magnetic fields. - Abstract: Magnetic shielding performance of superconducting YBaCu{sub 2}O{sub 7−x} (YBCO) thin film on an YBCO microbridge was analyzed in a multilayer structure. A sandwich type multilayer structure was fabricated onto a single crystal (1 0 0) SrTiO{sub 3} (STO) substrate in the form of YBCO/STO/YBCO by depositing a thin STO interlayer in between two YBCO layers. The top YBCO was patterned as 20 μm width meander-type microbridges and the bottom layer YBCO was used as magnetic shield. YBCO and STO thin films were deposited by dc and rf magnetron sputtering respectively, and the patterning was performed by using standard photolithography and wet etching. In order to enhance long-term stability of the final device, an additional STO thin film was deposited onto the device as an encapsulation layer. Electrical and magnetic characterizations of the YBCO thin film layers were carried out by means of ac magnetic susceptibility (χ–T) and resistance vs. temperature (R–T) measurements. The current–voltage (I–V) measurements were performed on the microbridges at 77 K by observing the shielding performance of the bottom YBCO layer under various applied magnetic fields. The results were compared with that of a same-type single layer YBCO device without a shielding layer. The zero field critical current value of the single layer 20 μm wide YBCO device was measured as 30 mA and decreased down to 20 mA as the field increased up to 100 mT. The same measurements on the multilayer device showed that the critical current values remained almost constant around 27 mA as the applied field increased.

  9. Ferromagnetic boundary magnetization properties of epitaxial Cr(2 - x)Al(x)O3 thin films

    Science.gov (United States)

    Fallarino, Lorenzo; Binek, Christian; Berger, Andreas

    2015-03-01

    The existence of an equilibrium net magnetization at (0001) surfaces is enabled by symmetry constrains for the magnetoelectric antiferromagnet α-Cr2O3. The occurrence of this boundary magnetization (BM) is furthermore roughness insensitive. The BM is hereby fully coupled to the bulk antiferromagnetic order parameter and can be reversed together with it by a combination of E and H fields in bulk materials, or solely by magnetic means for single crystal (0001) oriented thin chromia films. In order to understand whether the BM can be extended to alloys containing different oxide materials, we investigated the effect of Al2O3 doping onto the structural and magnetic properties of α-Cr2O3. We grew, using a hybrid growth procedure, 100 nm thick high-quality epitaxial Cr2-xAlxO3(0001) thin films in the concentration range between x =0 to x =0.6, preserving the original corundum crystal structure and symmetry. Using SQUID magnetometry, we showed that the critical temperature TN can be tuned by alloying with α-Al2O3 using the BM as a probe to study the magnetic transition. Furthermore, we were able to evaluate the critical exponent and the absolute BM values for different samples. Both properties are consistent with the expected values, corroborating the BM nature of the observed magnetic signals.

  10. Exchange Mechanisms in Long Range Ordered Thin Film Organic Magnetic Semiconductors

    Science.gov (United States)

    Rawat, N.; Headrick, R.; Furis, M.; McGill, S.; Kilanski, L.; Waterman, R.

    2014-03-01

    Magnetic exchange mechanisms in crystalline thin films of Metal Phthalocyanines (M-Pc) are explored using Magnetic Circular Dichroism (MCD) and SQUID measurements up to 10 T and 2K. Long range ordered thin films of organo-soluble derivatives of Co-Pc and Mn-Pc were fabricated using solution processing technique. In the case of Mn-Pc, our measurements show enhanced hybridization of ligand π-electronic states with the Mn d-orbitals. MCD active states beyond 1 μm have been observed for the first time, providing crucial information on the orbital arrangements of MPc's that result in competing (co-existing) long-range superexchange and indirect exchange reminiscent of RKKY. The evolution of Zeeman splitting of specific MCD-active states is very well described by enhanced effective π-electrons g-factors as large as 100, analogous to diluted magnetic semiconductors (DMS) systems. In Co-Pc MCD data indicates a weaker exchange interaction between delocalized charge carriers and d-like spin-polarized electrons, however SQUID measurements reveal magnetic ordering up to 180K. A comparison between Mn-Pc and Co-Pc and earlier results from the spin 1/2 Cu-Pc and their non-magnetic Zn-Pc counterpart, offers an interesting view on the role of long range order in magnetic interactions. NSF, MRI and CAREER programs: DMR- 0722451; DMR-0348354; DMR- 0821268; DMR-1056589.

  11. Longitudinal Hall effect in Terfecohan thin films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Duc, N.H. [Laboratory for Nano Magnetic Materials and Devices, Faculty of Engineering Physics and Nanotechnology, College of Technology, Vietnam National University, Hanoi, Buiding E3, 144 Xuan Thuy Road, Cau Giay, Hanoi (Viet Nam)]. E-mail: ducnh@vnu.edu.vn; Hong, N.T.M. [Laboratory for Nano Magnetic Materials and Devices, Faculty of Engineering Physics and Nanotechnology, College of Technology, Vietnam National University, Hanoi, Buiding E3, 144 Xuan Thuy Road, Cau Giay, Hanoi (Viet Nam); Teillet, J. [Groupe de Physique des Materiaux, Universite de Rouen, UMR CNRS 6634, 76801 St. Etienne du Rouvray (France)

    2007-09-15

    Longitudinal extraordinary Hall Effect (LEHE) of magnetic Tb(Fe{sub 0.55}Co{sub 0.45}){sub 1.5} (known as Terfecohan) thin films with perpendicular magnetic anisotropy has been investigated as a function of both the intensity of applied magnetic fields and the angle {alpha} between the applied field and film normal directions. The Hall voltage loops exhibit a parallelogram shape, which is almost similar to those of the perpendicular magnetization. The high-field Hall voltage susceptibility is positive at {alpha}=0. Its value decreases with increasing {alpha} and changes in sign at {alpha} {sub m}=20{sup o}, which is considered as the easy magnetizable direction of the film. This finding is comparable with those obtained from the magnetization, magnetic force microscopy (MFM) and conversion electron Moessbauer spectra (CEMS) measurements. The obtained LEHE behaviors are rather promising for applications such as magnetic recording heads and magnetic field detectors, where a large output signal is required at low magnetic fields.

  12. Longitudinal Hall effect in Terfecohan thin films with perpendicular magnetic anisotropy

    Science.gov (United States)

    Duc, N. H.; Hong, N. T. M.; Teillet, J.

    2007-09-01

    Longitudinal extraordinary Hall Effect (LEHE) of magnetic Tb(Fe 0.55Co 0.45) 1.5 (known as Terfecohan) thin films with perpendicular magnetic anisotropy has been investigated as a function of both the intensity of applied magnetic fields and the angle α between the applied field and film normal directions. The Hall voltage loops exhibit a parallelogram shape, which is almost similar to those of the perpendicular magnetization. The high-field Hall voltage susceptibility is positive at α=0. Its value decreases with increasing α and changes in sign at αm=20°, which is considered as the easy magnetizable direction of the film. This finding is comparable with those obtained from the magnetization, magnetic force microscopy (MFM) and conversion electron Mössbauer spectra (CEMS) measurements. The obtained LEHE behaviors are rather promising for applications such as magnetic recording heads and magnetic field detectors, where a large output signal is required at low magnetic fields.

  13. Composition influence on the microstructures and magnetic properties of FePt thin films

    Institute of Scientific and Technical Information of China (English)

    Liu Li-Wang; Dang Hong-Gang; Sheng Wei; Wang Ying; Cao Jiang-Wei; Bai Jian-Min; Wei Fu-Lin

    2013-01-01

    The FexPt100-x (10 nm) (x =31-51) thin films are fabricated on Si (100) substrates by using magnetron sputtering.The highly ordered L10 FePt phase is obtained after post-annealing at 700 ℃C in Fe47Pt53 thin film.The sample shows good perpendicular anisotropy with a square loop and a linear loop in the out-of-plane and the in-plane direction,respectively.The variations of the magnetic domains are investigated in the films when the content value of Fe changes from 31% to 51%.

  14. Magnetic and Transport Properties of Ferromagnetic Semiconductor GaDyN Thin Film

    Institute of Scientific and Technical Information of China (English)

    LI Xi-Jun; ZHOU YI-Kai; KIM M.; KIMURA S.; TERAGUCHI N.; EMURA S.; HASEGAWA S.; ASAHI H.

    2005-01-01

    @@ Magnetic properties and temperature dependence of electrical transport properties of rare-earth-metal Dy-doped GaN thin film are experimentally studied with a superconducting quantum interference device magnetometer and van der Pauw method. It was found that this thin nitride film has both semiconductor properties and ferromagnetism from 10K to room temperature. The dopant-band (conducting band due to doping) electron conduction dominates the transport properties of this film at low temperatures. These results indicate that Dy-doped GaN is an n-type ferromagnetic semiconductor at room temperature.

  15. Preparation of hard magnetic materials in thin film form

    Energy Technology Data Exchange (ETDEWEB)

    Pigazo, F.; Palomares, F.J. [Instituto de Ciencia de Materiales de Madrid-CSIC, c/ Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain); Cebollada, F. [EUITT-UPM, Carretera de Valencia km 7, 28031 Madrid (Spain); Gonzalez, J.M. [Unidad Asociada ICMM-IMA, c/ Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)], E-mail: jesus.m.gonzalez@icmm.csic.es

    2008-07-15

    We report on the preparation, by means of pulsed laser ablation deposition, of trilayers of nominal composition Cr/SmCo{sub 5}/Cr//Si with thicknesses in the order of 250/240/125 nm, respectively. According to the results of the structural, chemical and magnetic characterizations performed in our as-deposited samples, the Sm-Co layer was structurally amorphous, exhibited abrupt compositional interfaces with the capping and buffering layers, and coercivities of a few hundreds of Oe. Magnetic hardness was developed upon submitting the samples to current anneals under vacuum at temperatures in the range of 540-670 deg. C. The hardening process was followed in detail by correlating the phase distribution, the nature of the interlayer atomic diffusion processes, the occurrence of textures and the temperature dependence of the coercive force. From our results we conclude about (i) the occurrence of a large degree of Co diffusion/segregation, which results in the detection, from the diffraction and magnetometric results, of the presence of CoCr alloys in the treated samples, and (ii) the close correlation, evidenced from the fits of the temperature dependence of the coercive force to the micromagnetic model, between the coercivity optimization and the crystallinity enhancement of the SmCo{sub 5} grains.

  16. Magnetotransport Properties of Thin Films of Magnetic Perovskites

    Science.gov (United States)

    Jakob, Gerhard; Westerburg, Wilhelm; Martin, Frank; Reisinger, Daniel; Auth, Nicole

    In this article we show magnetotransport of two prototypical (nearly) half metallic perowskites La2/3Ca1/3MnO3 and Sr2FeMoO6. In a half metal the spin polarisation at the Fermi energy is complete and tunneling magnetoresistive devices of high sensitivity can be realized with small external magnetic fields. In the vicinity of the metal-insulator phase transition (MIT) temperature of the manganite an external magnetic field can induce 'colossal' magnetoresistive effects. In the simple perovskites La1-xCaxMnO3 the charge transport above the MIT is of polaronic nature. Hall-effect measurements on the compound La0.67Ca0.33MnO3 below the MIT show a compensated Fermi-surface consisting of electron and hole contributions and an unusual quadratic temperature dependence of the resistivity. In Sr2FeMoO6 we found a clear correlation between electrical conductivity and ordered occupation of the Fe, Mo atomic positions. While the low temperature ferrimagnetic phase shows similar transport the high temperature phase stays metallic.

  17. Magnetotail Current Sheet Thinning and Magnetic Reconnection Dynamics in Global Modeling of Substorms

    Science.gov (United States)

    Kuznetsova, M. M.; Hesse, M.; Rastaetter, L.; Toth, G.; DeZeeuw, D. L.; Gombosi, T. I.

    2008-01-01

    Magnetotail current sheet thinning and magnetic reconnection are key elements of magnetospheric substorms. We utilized the global MHD model BATS-R-US with Adaptive Mesh Refinement developed at the University of Michigan to investigate the formation and dynamic evolution of the magnetotail thin current sheet. The BATSRUS adaptive grid structure allows resolving magnetotail regions with increased current density up to ion kinetic scales. We investigated dynamics of magnetotail current sheet thinning in response to southwards IMF turning. Gradual slow current sheet thinning during the early growth phase become exponentially fast during the last few minutes prior to nightside reconnection onset. The later stage of current sheet thinning is accompanied by earthward flows and rapid suppression of normal magnetic field component $B-z$. Current sheet thinning set the stage for near-earth magnetic reconnection. In collisionless magnetospheric plasma, the primary mechanism controlling the dissipation in the vicinity of the reconnection site is non-gyrotropic effects with spatial scales comparable with the particle Larmor radius. One of the major challenges in global MHD modeling of the magnetotail magnetic reconnection is to reproduce fast reconnection rates typically observed in smallscale kinetic simulations. Bursts of fast reconnection cause fast magnetic field reconfiguration typical for magnetospheric substorms. To incorporate nongyritropic effects in diffusion regions we developed an algorithm to search for magnetotail reconnection sites, specifically where the magnetic field components perpendicular to the local current direction approaches zero and form an X-type configuration. Spatial scales of the diffusion region and magnitude of the reconnection electric field are calculated self-consistently using MHD plasma and field parameters in the vicinity of the reconnection site. The location of the reconnection sites and spatial scales of the diffusion region are updated

  18. Transient Grating Spectroscopy in Magnetic Thin Films : Simultaneous Detection of Elastic and Magnetic Dynamics

    NARCIS (Netherlands)

    Janusonis, J.; Jansma, T.; Chang, C. L.; Liu, Qi; Gatilova, A.; Lomonosov, A. M.; Shalagatskyi, V.; Pezeril, T.; Temnov, V. V.; Tobey, R. I.

    2016-01-01

    Surface magnetoelastic waves are coupled elastic and magnetic excitations that propagate along the surface of a magnetic material. Ultrafast optical techniques allow for a non-contact excitation and detection scheme while providing the ability to measure both elastic and magnetic components individu

  19. Magnetic layer thickness dependence of all-optical magnetization switching in GdFeCo thin films

    Science.gov (United States)

    Yoshikawa, Hiroki; El Moussaoui, Souliman; Terashita, Shinnosuke; Ueda, Ryohei; Tsukamoto, Arata

    2016-07-01

    To clarify the relationship between all-optical magnetization switching (AOS) and nonlocal and nonadiabatic energy dissipation process, we focus on the contribution from energy dissipation in the depth direction. Differently designed structure dependence of created magnetic domain is observed from the reversal phenomenon, AOS, or multidomains by thermomagnetic nucleation (TMN) in GdFeCo multilayer thin films. TMN depends on the shared absorbed energy throughout the continuous metallic volume. On the other hand, AOS critically depends on nonadiabatic energy dissipation process with the electron system in sub-picoseconds. Furthermore, the laser fluence dependence of AOS-created domain sizes indicates that the value of irradiated laser fluence threshold per magnetic domain volume is almost constant. However, a lower laser irradiation fluence below 1-2 mW has a larger value and thickness dependence. From these results, we suggest that AOS depends on energy dissipation from the incident surface in the depth direction for a few picoseconds.

  20. Non-collinear magnetization configuration in interlayer exchange coupled magnetic thin films

    Science.gov (United States)

    Choi, J.; Min, B.-C.; Kim, J.-Y.; Park, B.-G.; Park, J. H.; Lee, Y. S.; Shin, K.-H.

    2011-09-01

    Element specific magnetic hysteresis loops of the interlayer exchange coupled CoFeB/Ru/[Co/Ni]4 structure were measured utilizing x-ray magnetic circular dichroism. It was found that the Co/Ni multilayer and the CoFeB layer have Ru thickness dependent oscillatory interlayer coupling. Due to its interlayer coupling with the perpendicularly magnetized Co/Ni multilayer, the CoFeB magnetization direction is slightly tilted out-of-plane from its in-plane magnetic easy axis. Quantitative measurements show that the tilting angle is small (magnetic field (˜50 Oe) applied to this structure will result in a completely in-plane CoFeB magnetization.

  1. Analytical Newtonian models of finite thin disks in a magnetic field

    CERN Document Server

    Cardona-Rueda, Edinson

    2013-01-01

    Axially symmetric Newtonian thin disks of finite extension in presence of magnetic field are studied based on the well-known Morgan-Morgan solutions. The source of the magnetic field is constructed separating the equation corresponding to the Ampere's law of electrodinamic in spheroidal oblate coordinates. This produces two associated Legendre equations of first order for the magnetic potential and hence that can be expressed as a series of associated Legendre functions of the same order. The discontinuity of its normal derivate across the disk allows us interpreter the source of the magnetic field as a ringlike current distribution extend on the plane of the disk. We also study the motion of charged test particles around of the disks. In particular we analysis the circular speed curves or rotation curve for equatorial circular orbits of particles both inside and outside the disk. The stability of the orbits is analyzed for radial perturbation using a extension of the Rayleigh criterion.

  2. Hall current sensor IC with integrated Co-based alloy thin film magnetic concentrator

    Science.gov (United States)

    Palumbo, V.; Marchesi, M.; Chiesi, V.; Paci, D.; Iuliano, P.; Toia, F.; Casoli, F.; Ranzieri, P.; Albertini, F.; Morelli, M.

    2013-01-01

    This work deals with a cobalt-based alloy thin film magnetic concentrator (MC) which is fully integrated on a Hall sensor integrated circuit (IC) developed in the 0.35 µm Bipolar CMOS DMOS (BCD) technology on 8" silicon wafer. An amorphous magnetic film with a thickness of 1µm, coercitive field Hc<10A/m and saturation magnetization (µ0MS) of 0.45T has been obtained with a sputtering process. The Hall sensor IC has shown sensitivity to magnetic field at room temperature of 240V/AT without concentrator and 2550V/AT with concentrator, gaining a factor of 10.5. A current sensor demonstrator has been realized showing linear response in the range -50 to 50A.

  3. Hall current sensor IC with integrated Co-based alloy thin film magnetic concentrator

    Directory of Open Access Journals (Sweden)

    Albertini F.

    2013-01-01

    Full Text Available This work deals with a cobalt-based alloy thin film magnetic concentrator (MC which is fully integrated on a Hall sensor integrated circuit (IC developed in the 0.35 µm Bipolar CMOS DMOS (BCD technology on 8” silicon wafer. An amorphous magnetic film with a thickness of 1µm, coercitive field Hc<10A/m and saturation magnetization (µ0MS of 0.45T has been obtained with a sputtering process. The Hall sensor IC has shown sensitivity to magnetic field at room temperature of 240V/AT without concentrator and 2550V/AT with concentrator, gaining a factor of 10.5. A current sensor demonstrator has been realized showing linear response in the range -50 to 50A.

  4. Structural and magnetic studies of Cr doped nickel ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, Kalpana, E-mail: kalpanapanwar99@gmail.com [Department of Pure & Applied Physics, University of Kota, Kota-324010 (India); Department of Physics, Govt. Women Engg. College, Ajmer-305002 (India); Heda, N. L. [Department of Pure & Applied Physics, University of Kota, Kota-324010 (India); Tiwari, Shailja [Department of Physics, Govt. Women Engg. College, Ajmer-305002 (India); Bapna, Komal; Ahuja, B. L. [Department of Physics, M. L. Sukhadia University, Udaipur-313001 (India); Choudhary, R. J.; Phase, D. M. [UGC-DAE Consortium for Scientific Research, University Campus, Indore-452017 (India)

    2016-05-23

    We have studied the structural and magnetic properties of Cr doped nickel ferrite thin films deposited on Si (100) and Si (111) using pulsed laser deposition technique. The films were deposited under vacuum and substrate temperature was kept at 700°C. X-ray diffraction analysis revealed that films on both substrates have single phase cubic spinel structure. However, the film grown on Si (111) shows better crystalline behavior. Fourier transform infrared spectroscopy suggests that films on both substrates have mixed spinel structure. These films show magnetic hysteresis behavior and magnetization value of film on Si (100) is larger than that on Si (111). It turns out that structural and magnetic properties of these two films are correlated.

  5. Effect of quenching on the magnetic properties of Mg-ferrite thin films

    Directory of Open Access Journals (Sweden)

    Himadri Roy Dakua

    2016-05-01

    Full Text Available We have investigated the microstructural and magnetic properties of the post annealed slow cooled and quenched Mg-ferrite thin films. The microstructural properties of these films were studied through XRD, TEM and SEM. The magnetic properties were studied using VSM at 300K and 10K. The quenched film showed ∼1.66 times higher magnetization at room temperature (RT compared to the bulk and the slow cooled film (4πMS of bulk∼1880 Gauss at RT though the crystal phase, grain size and thickness of both the films were similar. The change in the cation distribution is the plausible origin of large magnetization observed in the quenched (rapid cooled film.

  6. Magnetic Property in large array cobalt antidot thin film using polymer-assisted nanosphere lithography

    Science.gov (United States)

    Lee, Wei-Li; Ho, Chi-Chih; Hsieh, Yung-Wu; Juan, Wen-Tau; Lin, Keng-Hui

    2010-03-01

    We have developed a new method to prepare monolayer of close- packed nanospheres (NSs) over large area onto a substrate of any kind utilizing polymer bridging effect. The NSs packing domain can be as large as 1 cmx1 cm which is demonstrated from its diffraction pattern. It was then used as a template to fabricate series of cobalt antidot thin films with different antidot diameter ranging from 100nm to 180nm. Because of the good periodicity and less defects in our nanostructured samples, we would be able to not only qualitatively study their magnetic properties but also quantitatively. As the antidot diameter increases, the surface to bulk volume fraction increases and the surface magnetism becomes more prominent. We found a systematic increase in magnetic coercivity with the antidote diameter, while the saturation magnetization drops at large antidote diameter. Detailed analysis and their implication will be discussed.

  7. Effects of thermal annealing on the magnetic interactions in nanogranular Fe-Ag thin films

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, J.; Fdez-Gubieda, M.L.; Svalov, A. [Departamento de Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), Campus de Leioa, 48940 Leioa (Spain); Meneghini, C. [Dipartimento di Fisica ' E. Amaldi' , Universita degli Studi Roma Tre, 00146 Roma (Italy); Orue, I. [SGIker, Universidad del Pais Vasco (UPV/EHU), Campus de Leioa, 48940 Leioa (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Fe{sub x}Ag{sub 100-x} granular thin films with competing interactions (25 {<=} x{<=} 35). Black-Right-Pointing-Pointer Annealing up to 200 Degree-Sign C mainly modifies the interface of Fe nanoparticles. Black-Right-Pointing-Pointer Annealing reduces RKKY interactions in Fe{sub 25}Ag{sub 75}. Black-Right-Pointing-Pointer Annealing favors exchange interactions and ferromagnetic order in Fe{sub 35}Ag{sub 65}. - Abstract: In this paper we have studied, by analysing the evolution of the magnetic behaviour during thermal treatment, the role of the interparticle magnetic interactions in Fe{sub x}Ag{sub 100-x} granular thin films prepared by sputtering deposition technique. Two compositions have been selected: x = 25 and 35, below and around the magnetic percolation of the system, respectively, according to our previous works. The structure of these thin films has been studied by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) measurements. To analyse the magnetic behaviour, DC magnetic measurements have been carried out after progressively annealing the samples at different temperatures (0 {<=} T{sub ann} {<=} 200 Degree-Sign C). These measurements have revealed that, upon thermal treatment, the frustrated state at low temperatures (T < 80 K) for the x = 25 sample tends to disappear, probably due to the weakening of RKKY interactions after the segregation of soluted Fe atoms in the Ag matrix. However, dipolar interactions are not affected by the annealing. On the contrary, at x = 35, around the magnetic percolation, the annealing gives rise to an increasingly ordered interface, thereby enhancing the transfer of the direct exchange interactions.

  8. Ion irradiation effects on the magnetic anisotropy of Fe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Salazar, Josiane Bueno; Santos, Barbara Canto dos; Geshev, Julian Penkov; Schmidt, Joao Edgar; Schafer, Deise; Grande, Pedro Luis; Pereira, Luis Gustavo [Universidade Federal do Rio Grande do Sul (UFRGS), RS (Brazil). Inst. de Fisica

    2011-07-01

    Full text. The effects of low dimensionality can lead a system to show certain properties quite different from those observed in bulk systems. In general, some of these properties are obtained during manufacturing the sample. However, we may modify them after the deposition by several processes, for example, ion irradiation. In a recent work was observed that Fe thin films grown on Si (111) have a different magnetic behavior depending on the thickness. In our work, we analyzed Fe films with thickness of 60 angstrom and 300 angstrom, which presented the same magnetic characteristics observed previously. Later they were subjected to the irradiation of 20 MeV Au{sup +} ion, in an angle of 45 degrees to the normal of the films. The current density was 4 nA/cm{sup 2} and the fluency was 5 X 10{sup 11} ions/cm{sup 2}. Irradiated films presented an increase in the contribution of shape anisotropy due to the action of the ions. The observation of changes in magnetic behavior and morphological characteristics by ion irradiation was the main motivation for present work. In the present work we discuss the influence of ion irradiation in Fe (60 angstrom) films, whose projection of the beam direction in the plan is presents parallel and perpendicular to the easy axis of magnetization film, performed in an angle of 70 degrees to the normal of the film. We also want to understand the oxidation effects on the magnetic behavior of Fe thin films. This analysis was performed using the MEIS (Medium Energy Ion Scattering) technique, which is also interesting because it provides great accuracy in the study of depth profiles of extremely thin layers. A second work associated with the change effects in the magnetic behavior by ion irradiation is discussed based on samples that present the exchange bias phenomenon

  9. Epitaxial growth of magnetic ZnCuO thin films by pulsed laser deposition

    Science.gov (United States)

    Kim, Dong Hun; Kim, Tae Cheol; Lee, Seung Han; Jung, Hyun Kyu; Jeong, Jaeeun; Han, Seung Ho

    2017-02-01

    The crystal structure and magnetic properties of epitaxial ZnO thin films doped with 5 at% Cu on SrTiO3 (001) and (111) substrates were investigated. In the case of films deposited in oxygen, unique crystallographic growth directions on different substrates were observed, while a metallic phase was detected in films grown under vacuum. The Cu-doped ZnO thin films deposited on the SrTiO3 (111) substrates, with hexagonal structures, showed a single epitaxial relationship with the substrates, whereas those deposited on the SrTiO3 (001) substrates showed a double epitaxial growth mode. The epitaxial ZnCuO thin films deposited on the SrTiO3 (111) substrates under high vacuum exhibited a ferromagnetic signal at room temperature.

  10. Dip coated nickel zinc oxide thin films: Structural, optical and magnetic investigations

    Science.gov (United States)

    Kayani, Zohra Nazir; Kiran, Faiza; Riaz, Saira; Zia, Rehana; Naseem, Shahzad

    2015-01-01

    Dip-coating technique was used to deposit NiZnO thin films on glass substrates at varying withdrawal speed in the range of 150-350 mm/s and annealed at 500 °C for 4 h. X-ray diffraction (XRD) results showed that the deposited NiZnO thin films have a pure wurtzite structure without any significant change in the structure caused by substituting Zn ion with Ni ion. Crystallite size increased from 248 to 497 nm with increase in withdrawal speed. Vibrating Sample magnetometer (VSM) results indicated that NiZnO thin films exhibit ferromagnetic properties. Increase in saturation magnetization with increase in withdrawal speed is observed. Evaluated optical band gap of the films reduced from 3.18 eV to 2.50 eV with the increase in withdrawal speed of the substrate.

  11. Structural and Magnetic Anisotropy in Amorphous Terbium-Iron Thin Films

    Science.gov (United States)

    Hufnagel, Todd Clayton

    1995-01-01

    High density, removable media magnetooptic disk drives have recently begun to make significant gains in the information mass storage market. The media in these disks are amorphous rare-earth/transition-metal (RE-TM) alloys. One vital property of these materials is a large perpendicular magnetic anisotropy; that is, an easy axis of magnetization which is perpendicular to the plane of the film. A variety of theories, sometimes contradictory, have been proposed to account for this surprising presence of an anisotropic property in an amorphous material. Recent research indicates that there is an underlying atomic-scale structural anisotropy which is responsible for the observed magnetic anisotropy. Several different types of structural anisotropy have been proposed to account for the observed magnetic anisotropy, including pair-ordering anisotropy (anisotropic chemical short-range order) and bond orientation anisotropy (an anisotropy in coordination number or distances independent of chemical ordering). We have studied the structural origins of perpendicular magnetic anisotropy in amorphous Tb-Fe thin films by employing high-energy and anomalous dispersion x-ray scattering. The as-deposited films show a clear structural anisotropy, with a preference for Tb-Fe near neighbors to align in the out-of-plane direction. These films also have a large perpendicular magnetic anisotropy. Upon annealing, the magnetic anisotropy energy drops significantly, and we see a corresponding reduction in the structural anisotropy. The radial distribution functions indicate that the number of Tb-Fe near-neighbors increases in the in-plane direction, but does not change in the out-of-plane direction. Therefore, the distribution of Tb-Fe near-neighbors becomes more uniform upon annealing. We propose that the observed reduction in perpendicular magnetic anisotropy energy is a result of this change in structure. Our results support the pair -ordering anisotropy model of the structural anisotropy

  12. Uniaxial magnetic anisotropy of cobalt thin films on different substrates using CW-MOKE technique

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Vijay, E-mail: shuklavs@rrcat.gov.in [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Mukherjee, C. [Mechanical and Optical Support Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Chari, R. [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Rai, S. [Indus Synchrotron Utilization Division, Raja Ramnna Centre for Advanced Technology, Indore 452013 (India); Bindra, K.S. [Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Banerjee, A. [BARC training school at RRCAT and Homi Bhabha National Institute, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2014-12-15

    Cobalt thin films were deposited on GaAs, Si and Glass substrates by RF-magnetron sputtering. The structure was studied using atomic force microscopy, X-ray reflectivity and grazing incidence X-ray diffraction. Magnetic properties were determined with the magneto-optic Kerr effect. The deposited films have in-plane uniaxial anisotropy and after annealing the anisotropy reduces. The reduction in anisotropy may be due to release of stress and the remaining anisotropy after annealing may be due to shape anisotropy of the particulates. - Highlights: • Deposited cobalt thin films on different substrates and annealed at 300 °C. • Characterized as-grown and annealed films by GIXRD, AFM and MOKE. • Uniaxial magnetic anisotropy observed for all the samples. • Decrease in anisotropy on annealing may be due to release of stress during deposition.

  13. Magnetic, magnetooptical, and magnetotransport properties of Ti-substituted Co2FeGa thin films

    Science.gov (United States)

    Khovaylo, Vladimir; Rodionova, Valeria; Lyange, Maria; Chichay, Ksenia; Gan'shina, Elena; Novikov, Andrey; Zykov, Georgy; Bozhko, Alexei; Ohtsuka, Makoto; Umetsu, Rie Y.; Okubo, Akinari; Kainuma, Ryosuke

    2014-08-01

    Magnetic, magnetooptical and magnetotransport properties of Co50.3Fe20.3Ti5.6Ga23.8 thin films were studied for the as prepared as well as annealed samples. Measurements of transverse magnetooptical Kerr effect revealed that the spectral response of the films strongly depends on the structural ordering which can be manipulated by annealing conditions. Peculiarities in the magnetic properties of the films were attributed to the coexisting phases with different degree of structural disorder. Magnetoresistance of Co50.3Fe20.3Ti5.6Ga23.8 thin films was found to be linear in the fields above 1 T which is typical for half-Heusler systems as well as for Heusler-based ferromagnetic shape memory alloys.

  14. Three-dimensional simulations of thin ferro-fluid films and drops in magnetic fields

    Science.gov (United States)

    Conroy, Devin; Wray, Alex; Matar, Omar

    2016-11-01

    We consider the interfacial dynamics of a thin, ferrofluidic film flowing down an inclined substrate, under the action of a magnetic field, bounded above by an inviscid gas. The fluid is assumed to be weakly-conducting. Its dynamics are governed by a coupled system of the steady Maxwell's, the Navier-Stokes, and continuity equations. The magnetisation of the film is a function of the magnetic field, and is prescribed by a Langevin function. We make use of a long-wave reduction in order to solve for the dynamics of the pressure, velocity, and magnetic fields inside the film. The potential in the gas phase is solved with the use of Fourier Transforms. Imposition of appropriate interfacial conditions allows for the construction of an evolution equation for the interfacial shape, via use of the kinematic condition, and the magnetic field. We consider the three-dimensional evolution of the film to spawise perturbations by solving the non-linear equations numerically. The constant flux configuration is considered, which corresponds to a thin film and drop flowing down an incline, and a parametric study is performed to understand the effect of a magnetic field on the stability and structure of the formed drops. EPSRC UK platform Grant MACIPh (EP/L020564/1) and programme Grant MEMPHIS (EP/K003976/1).

  15. Dynamos and anti-dynamos as thin magnetic flux ropes in Riemannian spaces

    CERN Document Server

    de Andrade, L Garcia

    2007-01-01

    Two examples of magnetic anti-dynamos in magnetohydrodynamics (MHD) are given. The first is a 3D metric conformally related to Arnold cat fast dynamo metric: ${ds_{A}}^{2}=e^{-{\\lambda}z}dp^{2}+e^{{\\lambda}z}dq^{2}+dz^{2}$ is shown to present a behaviour of non-dynamos where the magnetic field exponentially decay in time. The curvature decay as z-coordinates increases without bounds. Some of the Riemann curvature components such as $R_{pzpz}$ also undergoes dissipation while component $R_{qzqz}$ increases without bounds. The remaining curvature component $R_{pqpq}$ is constant on the torus surface. The other anti-dynamo which may be useful in plasma astrophysics is the thin magnetic flux rope or twisted magnetic thin flux tube which also behaves as anti-dynamo since it also decays with time. This model is based on the Riemannian metric of the magnetic twisted flux tube where the axis possesses Frenet curvature and torsion. Since in this last example the Frenet torsion of the axis of the rope is almost zero, o...

  16. Magnetic properties and high frequency characteristics of FeCoN thin films

    Directory of Open Access Journals (Sweden)

    Tae-Jong Hwang

    2016-05-01

    Full Text Available (Fe65Co35N soft magnetic thin films were prepared by reactive RF magnetron sputtering with the sputtering power of 100 W on thermally oxidized Si substrate in various nitrogen partial pressures (PN2. A strong uniaxial in-plane magnetic anisotropy with the easy-axis coercive field as low as 1∼2 Oe was observed in films grown at PN2 in the range from 3.3% to 5.5%. The saturation magnetizations for those films were about 20 KG. Outside this range, almost isotropic magnetization curves were observed. Vector network analyzer and grounded coplanar waveguide were used to measure the ferromagnetic resonance (FMR signals up to 25 GHz. The FMR signals were detected only in anisotropic films and their FMR frequencies were well fit to the Kittel formula. The obtained g-values and damping parameters at magnetic fields >20 kOe for films grown at PN2 of 3.3%, 4.8% and 5.5% were 1.96, 1.86, 1.92 and 0.0055, 0.0047, 0.0046, respectively. This low damping factor qualifies FeCoN thin films for high-frequency applications.

  17. Magnetic properties and high frequency characteristics of FeCoN thin films

    Science.gov (United States)

    Hwang, Tae-Jong; Lee, Joonsik; Kim, Ki Hyeon; Kim, Dong Ho

    2016-05-01

    (Fe65Co35)N soft magnetic thin films were prepared by reactive RF magnetron sputtering with the sputtering power of 100 W on thermally oxidized Si substrate in various nitrogen partial pressures (PN2). A strong uniaxial in-plane magnetic anisotropy with the easy-axis coercive field as low as 1˜2 Oe was observed in films grown at PN2 in the range from 3.3% to 5.5%. The saturation magnetizations for those films were about 20 KG. Outside this range, almost isotropic magnetization curves were observed. Vector network analyzer and grounded coplanar waveguide were used to measure the ferromagnetic resonance (FMR) signals up to 25 GHz. The FMR signals were detected only in anisotropic films and their FMR frequencies were well fit to the Kittel formula. The obtained g-values and damping parameters at magnetic fields >20 kOe for films grown at PN2 of 3.3%, 4.8% and 5.5% were 1.96, 1.86, 1.92 and 0.0055, 0.0047, 0.0046, respectively. This low damping factor qualifies FeCoN thin films for high-frequency applications.

  18. Dipolar interactions in magnetic thin films: perpendicular to in-plane ordering transition

    CERN Document Server

    Santamarina-Rios, C

    2000-01-01

    We study by extensive Monte Carlo (MC) simulations magnetic properties of very thin films with Heisenberg spin model on a BCC lattice with (0 0 1) surfaces, taking into account long-range dipolar interactions and single-ion anisotropy. In a range of parameters, a transition from perpendicular to in-plane ordering at a finite temperature is found. A phase diagram is shown. We interpret this magnetization reorientation as an entropy effect generated by dipolar interaction. Discussion in connection with experiments is given.

  19. High-purity cobalt thin films with perpendicular magnetic anisotropy prepared by chemical vapor deposition

    Science.gov (United States)

    Ootera, Yasuaki; Shimada, Takuya; Kado, Masaki; Quinsat, Michael; Morise, Hirofumi; Nakamura, Shiho; Kondo, Tsuyoshi

    2015-11-01

    A study of the chemical vapor deposition (CVD) of high-purity cobalt thin films is described. The Co layer prepared by a thermal CVD technique with a Pt/Ta underlayer and a Pt cap layer shows a saturation magnetization (Ms) of ∼1.8 T and perpendicular magnetic anisotropy (PMA) with an anisotropy energy (Ku) of ∼105 J/m3. The cobalt thickness dependence of Ku reveals that the interfacial anisotropy at the Pt/Co interface is most likely the origin of the obtained PMA.

  20. Critical magnetic field of V/sub 3/Ga thin films with third element additions

    Energy Technology Data Exchange (ETDEWEB)

    Tedrow, P.M.; Bending, S.J.; Hammond, R.; Meservey, R.; Tkaczyk, J.E.

    1985-03-01

    We have made thin films of V-Ga superconductors by electron beam codeposition with approximately one percent additions of Nb, Ta, Sn, Pt or Pb. We have measured the high-magnetic field properties of these films to observe the effect of these impurities on spin-orbit scattering. Although the residual resistivity of the films was affected by the additional elements, the rate of spin-orbit scattering did not appear to increase.

  1. Electrical and magnetic properties of electrodeposited nickel incorporated diamond-like carbon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, B., E-mail: pandey.beauty@yahoo.com [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India); Das, D. [UGC-DAE CSR, Sector III/LB-8, Bidhan Nagar, Kolkata 700098 (India); Kar, A.K. [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India)

    2015-05-15

    Highlights: • Electrical and magnetic properties of DLC and Ni-DLC thin films are studied. • The ohmicity and conductivity of DLC films rise with nickel addition. • The ohmicity of Ni-DLC is enhanced with increase in dilution of electrolyte. • Dielectric loss is high for Ni-DLC and decreases with frequency till 100 kHz. • (m–H) and (m–T) curves of Ni-DLC indicate superparamagnetic behavior. - Abstract: Nanocomposite diamond-like carbon (DLC) thin films have been synthesized by incorporating nickel (Ni) nanoparticles in DLC matrix with varying concentration of nickel. DLC and Ni-DLC thin films have been deposited on ITO coated glass substrates employing low voltage electrodeposition method. Electrical properties of the samples were studied by measuring current–voltage characteristics and dielectric properties. The current approaches toward an ohmic behavior with metal addition. This tendency of increasing ohmicity is enhanced with increase in dilution of the electrolyte. The conductivity increases with Ni addition and interestingly it continues to increase with dilution of Ni concentration in the electrolyte in the range of our study. Magnetic properties for DLC and Ni-DLC thin film samples were examined by electron paramagnetic resonance (EPR) measurements and Super Conducting Quantum Interference Device (SQUID) measurements. g-Value for DLC is 2.074, whereas it decreases to 2.055 with Ni addition in the electrolyte. This decrement arises from the increased sp{sup 2} content in DLC matrix. The magnetic moment vs. magnetic field (m–H) curves of Ni-DLC indicate superparamagnetic behavior which may be due to ferromagnetic contribution from the incorporated nickel nanoparticles in the DLC matrix. The ZFC curve of Ni-DLC after the blocking temperature shows a combined contribution of ferromagnetic, superparamagnetic and paramagnetic nature of the materials persisting up to 300 K.

  2. Magneto-optical and magnetic properties in a Co/Pd multilayered thin film

    Science.gov (United States)

    Nwokoye, Chidubem A.; Bennett, Lawrence H.; Della Torre, Edward; Ghahremani, Mohammadreza; Narducci, Frank A.

    2017-01-01

    The paper describes investigation of ferromagnetism at low temperatures. We explored the magneto-optical properties, influenced by photon-magnon interactions, of a ferromagnetic Co/Pd multilayered thin film below and above the magnon Bose-Einstein Condensation (BEC) temperature. Analyses of SQUID and MOKE low temperature experimental results reveal a noticeable phase transition in both magnetic and magneto-optical properties of the material at the BEC temperature.

  3. Effects of thermal annealing on structural and magnetic properties of thin Pt/Cr/Co multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, J.K. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Satpati, B. [Center for Advanced Material Processing, Central Mechanical Engineering Research Institute, Mahatma Gandhi Avenue, Durgapur 713 209 (India); Oskar Liedke, Maciej [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); Gupta, A. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452 017 (India); Som, T., E-mail: tsom@iopb.res.i [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India)

    2010-11-15

    Thermal stability of thin Pt/Cr/Co multilayers and the subsequent changes in their structural, magnetic, and magneto-optical properties are reported. We observe CoCrPt ternary alloy phase formation due to annealing at temperatures about 773 K, which is accompanied by enhancement in the coercivity value. In addition, 360{sup o} domain wall superimposed on a monodomain like background has been observed in the pristine multilayer, which changes into a multidomain upon annealing at 873 K.

  4. Temperature dependent coercivity and magnetization of light rare-earth Nd doped permalloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chen [Physics Department, Southeast University, Nanjing 211189 (China); Fu, Yu [Physics Department, Southeast University, Nanjing 211189 (China); Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble (France); Zhang, Dong [Physics Department, Southeast University, Nanjing 211189 (China); School of Physics Science and Information Engineering, Liaocheng University, Liaocheng 252059 (China); Yuan, Shijun [Physics Department, Southeast University, Nanjing 211189 (China); Zhai, Ya, E-mail: yazhai@seu.edu.cn [Physics Department, Southeast University, Nanjing 211189 (China); Dong, Shuai [Physics Department, Southeast University, Nanjing 211189 (China); Zhai, Hongru [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-01-15

    The temperature dependence of the magnetic properties of Ni{sub 80}Fe{sub 20} thin films with dilute Nd dopants has been studied. The effect of Nd dopants on the hysteresis loops of Nd-doped Ni{sub 80}Fe{sub 20} thin films is small at room temperature but large at low temperature. The measurements show an interesting temperature dependence of the coercivity with different concentrations of Nd impurities, which might be related to the film structure. The temperature dependence of the saturation magnetization for Nd-doped Ni{sub 80}Fe{sub 20} thin films is fitted by a theoretical expression of spin-wave excitation plus Stoner-type-like contribution, in which the spin-wave excitation plays a main role at low temperature. The spin-wave stiffness constant D evaluated from the fitting shows a strong doping concentration dependence. - Highlights: • The abnormal coercivity behavior of Nd-doped Permalloy thin films is studied. • The mechanism of temperature dependence of coercivity is discussed. • The effect of Nd dopants on temperature dependence of Ms is studied. • Spin-wave excitations and Stoner-type excitations are discussed quantitatively.

  5. Magnetic and structural investigation of growth induced magnetic anisotropies in Fe50Co50 thin films

    Directory of Open Access Journals (Sweden)

    Neri I.

    2013-01-01

    Full Text Available In this paper, we investigate the magnetic properties of Fe50 Co50 polycrystalline thin films, grown by dc-magnetron sputtering, with thickness (t ranging from 2.5 nm up to 100 nm. We focused on the magnetic properties of the samples to highlight the effects of possible intrinsic stress that may develop during growth, and their dependence on film thickness. Indeed, during film deposition, due to the growth technique and growth conditions, a metallic film may display an intrinsic compressive or tensile stress. In our case, due to the Fe50Co50 magnetolastic properties, this stress may in its turn promote the development of magnetic anisotropies. Samples magnetic properties were monitored with a SQUID magnetometer and a magneto–optic Kerr effect apparatus, using both an in–plane and an out–of–plane magnetic field. Magnetoresistance measurements were collected, as well, to further investigate the magnetic behavior of the samples. Indications about the presence of intrinsic stress were obtained accessing samples curvature with an optical profilometer. For t ≤ 20 nm, the shape of the in-plane magnetization loops is squared and coercivity increases with t, possibly due to fact that, for small t values, the grain size grows with t. The magnetoresistive response is anisotropic in character. For t > 20 nm, coercivity smoothly decreases, the approach to saturation gets slower and the shape of the whole loop gets less and less squared. The magnetoresistive effect becomes almost isotropic and its intensity increases of about one order of magnitude. These results suggest that the magnetization reorientation process changes for t > 20 nm, and are in agreement with the progressive development of an out-of-plane easy axis. This hypothesis is substantiated by profilometric analysis that reveals the presence of an in-plane compressive stress.

  6. Annealed SnO{sub 2} thin films: Structural, electrical and their magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Mehraj, Sumaira, E-mail: sumairamehraj07@gmail.com [Department of Applied Physics, Aligarh Muslim University, Aligarh 202002 (India); Ansari, M. Shahnawaze, E-mail: shah.csengg@gmail.com [Center of Nanotechnology, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Alimuddin [Department of Applied Physics, Aligarh Muslim University, Aligarh 202002 (India)

    2015-08-31

    SnO{sub 2} thin films of ~ 150 nm thicknesses were deposited on quartz substrate by pulse laser deposition technique and annealed at 600–900 °C for 1 h with a variation of 100 °C per sample. The X-ray diffraction patterns show that as deposited SnO{sub 2} thin film was completely amorphous while annealed SnO{sub 2} thin films were randomly oriented, polycrystalline in nature and correspond to the rutile phase. The average crystallite size estimated using Scherrer and Williamson–Hall equations was found to increase with annealing temperature. In addition to the three fundamental Raman peaks at 473 cm{sup −1}, 627 cm{sup −1} and 766 cm{sup −1} corresponding to the tetragonal rutile phase of SnO{sub 2}, two IR active Raman bands and one Raman forbidden mode were also observed at 500 cm{sup −1}, 690 cm{sup −1} and 544 cm{sup −1} respectively. The dc resistivity measurements in the temperature range of 297–400 K show semiconducting behavior of all the annealed thin films. Room temperature dielectric properties of all the samples show dispersion which is explained in the light of Koop's theory based on Maxwell–Wagner two layer models. The dielectric parameters: real part of dielectric constant, dielectric loss and ac conductivity show their maximum value for SnO{sub 2} film sample annealed at 600 °C. The dielectric loss shows anomalous behavior and exhibits relaxation peaks (Debye peaks) at lower and middle frequencies. Complex impedance plots (Nyquist plots) for annealed SnO{sub 2} thin films show two well-resolved semicircles corresponding to two different electrical transport mechanisms which stand for grain and grain boundary. It is observed that the contribution of grains in the conduction process starts dominating over the grain boundary with the increase in annealing temperature. From a magnetic hysteresis loop, it is clear that all the single phase SnO{sub 2} thin films annealed at different temperatures are ferromagnetic at room

  7. Critical behavior of zero-field magnetic fluctuations in perpendicularly magnetized thin films

    Science.gov (United States)

    Balk, A. L.; Stiles, M. D.; Unguris, J.

    2014-11-01

    We use video-rate magneto-optical Kerr effect microscopy to study zero-field magnetic fluctuations in a perpendicularly magnetized cobalt film at room temperature, prepared near a spin reorientation transition. Globally, the film has zero net moment but local areas continually undergo thermal magnetic fluctuations between saturated states. Position resolved hysteresis loops show the fluctuations occur at sample locations close to the spin reorientation transition. Furthermore, nearby fluctuations interact magnetostatically, acting to maintain the overall zero net magnetization. The measured scaling exponent of the fluctuation areas τ is consistent with 4 /3 .

  8. Multiferroic BiFeO{sub 3} thin films: Structural and magnetic characterization

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Z. [Physics Department, Faculty of Science (Girls Branch), Al-Azhar University, Cairo (Egypt); Atta, A. [National Center for Radiation Research and Technology (NCRRT), Nasr City, Cairo (Egypt); Abbas, Y. [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt); Sedeek, K.; Adam, A.; Abdeltwab, E. [Physics Department, Faculty of Science (Girls Branch), Al-Azhar University, Cairo (Egypt)

    2015-02-27

    BiFeO{sub 3} (BFO) film has been deposited on indium tin oxide (ITO) substrate by a simple sol–gel spin-coating technique. The crystal phase composition, surface morphology, topography and magnetization measurements of the BFO thin film were investigated using grazing incidence X-ray diffraction (GIXRD), scanning electronic microscope (SEM), atomic force microscope and vibrating sample magnetometer, respectively. GIXRD analysis revealed that the film was fully crystallized and no impure phase was observed. Cross-section SEM results indicated that compact and homogeneous BFO thin film was deposited on ITO with a thickness of about 180 nm. Moreover, most of A and E-symmetry normal modes of R3c BFO were assigned by Raman spectroscopy. We report here that the pure phase BFO film shows ferromagnetism at room temperature with remarkably high saturation magnetization of 63 kA m{sup −1}. Our results are discussed mainly in correlation with the condition of processing technique and destruction of the spiral spin cycloid at interface layers and grain boundaries. - Highlights: • Multiferroic BiFeO{sub 3} (BFO) thin film was prepared by sol–gel spin-coating method. • BFO film w asdeposited on indium tin oxide substrate with a thickness of 180 nm. • The film exhibits pure rhombohedral perovskite structure. • High saturation magnetization was recorded for our film at room temperature.

  9. Magnetic and microwave properties of amorphous FeCoNbBCu thin films

    Science.gov (United States)

    Bi, Mei; Wang, Xin; Lu, Haipeng; Deng, Longjiang; Sunday, Katie Jo; Taheri, Mitra L.; Harris, Vincent G.

    2016-01-01

    The soft magnetic and microwave properties of amorphous FeCoNbBCu thin films with thicknesses varying from 70 nm to 450 nm have been systematically investigated. Due to the amorphous structure, the coercivity is 1.5 Oe in thicker films. The thickness-dependent microwave characteristics of the films were measured over the range 0.5-6 GHz and analyzed using the Landau-Lifshitz-Gilbert equation. Without applying magnetic field during deposition and measurement, an in-plane uniaxial anisotropy in amorphous thin films was obtained, ranging from 21 to 45 Oe. The interface interaction between substrate and film is confirmed to be the origin of the induced anisotropy, whereas the volume anisotropy contribution is more pronounced with increasing film thickness. For films possessing an in-plane uniaxial anisotropy, the shift of resonance frequency with thickness is observed and verified by the Kittel equation. The demonstration of a controllable and tunable anisotropy suggests that the FeCoNbBCu thin films have potential application as magnetic materials for Spintronics-based microwave devices.

  10. Tuning magnetic exchange interactions in crystalline thin films of substituted Cobalt Phthalocyanine

    Science.gov (United States)

    Rawat, Naveen; Manning, Lane; Hua, Kim-Ngan; Headrick, Randall; Bishop, Michael; McGill, Stephen; Waterman, Rory; Furis, Madalina

    Magnetic exchange interactions in diluted organometallic crystalline thin film alloys of Phthalocyanines (Pcs) made of a organo-soluble derivatives of Cobalt Pc and metal-free (H2Pc) molecule and is investigated. To this end, we synthesized a organosoluble CoPc and successfully employed a novel solution-based pen-writing deposition technique to fabricate long range ordered thin films of mixtures of different ratios ranging from 1:1 to 10:1 H2Pc:CoPc. Our previous magnetic circular dichroism (MCD) results on the parent CoPc crystalline thin films identified different electronic states mediating exchange interactions and indirect exchange interaction competing with superexchange interaction. This understanding of spin-dependent exchange interaction between delocalized π-electrons with unpaired d spins along with the excitonic delocalization character enabled the further tuning of these interactions by essentially varying the spatial distance between the spins. Furthermore, high magnetic field (B CAREER and EPM program Awards: DMR-0722451, DMR-0821268, DMR-1307017 and DMR-1056589, DMR-1229217.

  11. Scanning probe microscopy: instrumentation and applications on thin films and magnetic multilayers.

    Science.gov (United States)

    Karoutsos, Vagelis

    2009-12-01

    In this article we present a review on instrumentation and the modes of operation of a scanning probe microscope. In detail, we review the main techniques of Scanning Probe Microscopy (SPM), which are Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM), focusing our attention on the latter one. The AFM instrument provides information on the roughness and grain size of thin films. As an example we review recent results on two metallic thin film systems: thin Ag films deposited on glass, and Ni/Pt compositionally modulated multilayers deposited on glass, Si, and polyimide substrates. To show the validity of the grain size measurements, we compare the data with the ones resulting from X-ray diffraction (XRD) measurements. We show that the AFM results are reliable for grain diameters as small as 14 nm, which is approximately comparable to the tip radius. Finally, we deal with Magnetic Force Microscopy (MFM) results on Co/Pt and Co/Au multilayers. We observe perpendicularly magnetized domains. The domain configurations are correlated to the magnetization hysteresis curves.

  12. Dependence of the magnetization on the interface morphology in ultra-thin magnetic/non-magnetic films: Monte Carlo approach

    Energy Technology Data Exchange (ETDEWEB)

    Razouk, A. [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco); Sahlaoui, M., E-mail: msahlaoui@yahoo.fr [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco); Sajieddine, M. [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco)

    2009-07-30

    Using Monte Carlo simulations, we have studied the dependence of magnetic properties on interface morphology in magnetic/non-magnetic (M/NM) multilayers. Our aim is to relate macroscopic magnetic properties of the multilayers to their concentration profile at the interface. Our model consists of an alternate staking of magnetic and non-magnetic layers with disordered interfaces. We have considered different concentration and the existence of local magnetic domains at the interface. The results indicate the crucial dependence of magnetization amplitude with interface multilayers atomic composition and the spatial arrangement of magnetic atoms. In particular, we show that isolated islands at the interface leads to the apparition of super-paramagnetic behavior.

  13. Oxygen-enabled control of Dzyaloshinskii-Moriya Interaction in ultra-thin magnetic films

    KAUST Repository

    Belabbes, Abderrezak

    2016-04-22

    The search for chiral magnetic textures in systems lacking spatial inversion symmetry has attracted a massive amount of interest in the recent years with the real space observation of novel exotic magnetic phases such as skyrmions lattices, but also domain walls and spin spirals with a defined chirality. The electrical control of these textures offers thrilling perspectives in terms of fast and robust ultrahigh density data manipulation. A powerful ingredient commonly used to stabilize chiral magnetic states is the so-called Dzyaloshinskii-Moriya interaction (DMI) arising from spin-orbit coupling in inversion asymmetric magnets. Such a large antisymmetric exchange has been obtained at interfaces between heavy metals and transition metal ferromagnets, resulting in spin spirals and nanoskyrmion lattices. Here, using relativistic first-principles calculations, we demonstrate that the magnitude and sign of DMI can be entirely controlled by tuning the oxygen coverage of the magnetic film, therefore enabling the smart design of chiral magnetism in ultra-thin films. We anticipate that these results extend to other electronegative ions and suggest the possibility of electrical tuning of exotic magnetic phases.

  14. MAGNETIC-ELASTIC BUCKLING OF A THIN CURRENT CARRYING PLATE SIMPLY SUPPORTED AT THREE EDGES

    Institute of Scientific and Technical Information of China (English)

    WANG Zhiren; WANG Ping; BAI Xiangzhong

    2008-01-01

    The magnetic-elasticity buckling problem of a current plate under the action of a mechanical load in a magnetic field was studied by using the Mathieu function. According to the magnetic-elasticity non-linear kinetic equation, physical equations, geometric equations, the expression for Lorenz force and the electrical dynamic equation, the magnetic-elasticity dynamic buckling equation is derived. The equation is changed into a standard form of the Mathieu equation using Galerkin's method. Thus, the buckling problem can be solved with a Mathieu equation. The criterion equation of the buckling problem also has been obtained by discussing the eigenvalue relation of the coefficients λ and η in the Mathieu equation. As an example, a thin plate simply supported at three edges is solved here. Its magnetic-elasticity dynamic buckling equation and the relation curves of the instability state with variations in some parameters are also shown in this paper. The conclusions show that the electrical magnetic forces may be controlled by changing the parameters of the current or the magnetic field so that the aim of controlling the deformation, stress, strain and stability of the current carrying plate is achieved.

  15. Structural and magnetic studies of thin Fe57 films formed by ion beam assisted deposition

    Science.gov (United States)

    Lyadov, N. M.; Bazarov, V. V.; Vagizov, F. G.; Vakhitov, I. R.; Dulov, E. N.; Kashapov, R. N.; Noskov, A. I.; Khaibullin, R. I.; Shustov, V. A.; Faizrakhmanov, I. A.

    2016-08-01

    Thin Fe57 films with the thickness of 120 nm have been prepared on glass substrates by using the ion-beam-assisted deposition technique. X-ray diffraction, electron microdiffraction and Mössbauer spectroscopy studies have shown that as-deposited films are in a stressful nanostructured state containing the nanoscaled inclusions of α-phase iron with the size of ∼10 nm. Room temperature in-plane and out-of-plane magnetization measurements confirmed the presence of the magnetic α-phase in the iron film and indicated the strong effect of residual stresses on magnetic properties of the film as well. Subsequent thermal annealing of iron films in vacuum at the temperature of 450 °C stimulates the growth of α-phase Fe crystallites with the size of up to 20 nm. However, electron microdiffraction and Mössbauer spectroscopic data have shown the partial oxidation and carbonization of the iron film during annealing. The stress disappeared after annealing of the film. The magnetic behaviour of the annealed samples was characterized by the magnetic hysteresis loop with the coercive field of ∼10 mT and the saturation magnetization decreased slightly in comparison with the α-phase Fe magnetization due to small oxidation of the film.

  16. Perpendicular Magnetic Anisotropy in Amorphous Ferromagnetic CoSiB/Pd Thin-Film Layered Structures.

    Science.gov (United States)

    Jung, Sol; Yim, Haein

    2015-10-01

    Spin transfer torque (STT) induced switching of magnetization has led to intriguing and practical possibilities for magnetic random access memory (MRAM). This form of memory, called STT-MRAM, is a strong candidate for future memory applications. This application usually requires a large perpendicular magnetic anisotropy (PMA), large coercivity, and low saturation magnetization. Therefore, we propose an amorphous ferromagnetic CoSiB alloy and investigate CoSiB/Pd multilayer thin films, which have a large PMA, large coercivity, and low saturation magnetization. In this research, we propose a remarkable layered structure that could be a candidate for future applications and try to address a few factors that might affect the variation of PMA, coercivity, and saturation magnetization in the CoSiB/Pd multilayers. We investigate the magnetic properties of the CoSiB/Pd multilayers with various thicknesses of the CoSiB layer. The coercivity was obtained with a maximum of 228 Oe and a minimum value of 91 Oe in the [CoSiB 7 Å/Pd 14 Å], and [CoSiB 9 Å/Pd 14 Å], multilayers, respectively. The PMA arises from tCoSiB = 3 Å to tCoSiB = 9 Å and disappears after tCoSiB = 9 Å.

  17. Effect of microstructural evolution on magnetic properties of Ni thin films

    Indian Academy of Sciences (India)

    Prashant Kumar; M Ghanashyam Krishna; A K Bhattacharya

    2009-06-01

    The magnetic properties of Ni thin films, in the range 20–500 nm, at the crystalline–nanocrystalline interface are reported. The effect of thickness, substrate and substrate temperature has been studied. For the films deposited at ambient temperatures on borosilicate glass substrates, the crystallite size, coercive field and magnetization energy density first increase and achieve a maximum at a critical value of thickness and decrease thereafter. At a thickness of 50 nm, the films deposited at ambient temperature onto borosilicate glass, MgO and silicon do not exhibit long-range order but are magnetic as is evident from the non-zero coercive field and magnetization energy. Phase contrast microscopy revealed that the grain sizes increase from a value of 30–50 nm at ambient temperature to 120–150 nm at 503 K and remain approximately constant in this range up to 593 K. The existence of grain boundary walls of width 30–50 nm is demonstrated using phase contrast images. The grain boundary area also stagnates at higher substrate temperature. There is pronounced shape anisotropy as evidenced by the increased aspect ratio of the grains as a function of substrate temperature. Nickel thin films of 50 nm show the absence of long-range crystalline order at ambient temperature growth conditions and a preferred [111] orientation at higher substrate temperatures. Thin films are found to be thermally relaxed at elevated deposition temperature and having large compressive strain at ambient temperature. This transition from nanocrystalline to crystalline order causes a peak in the coercive field in the region of transition as a function of thickness and substrate temperature. The saturation magnetization on the other hand increases with increase in substrate temperature.

  18. Study on optimization of YBCO thin film stack for compact NMR magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.B., E-mail: kim@elec.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530 (Japan); Kimoto, T. [Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530 (Japan); Hahn, S.; Iwasa, Y.; Voccio, J. [Francis Bitter Magnet Laboratory, MIT, Cambridge, MA 02139 (United States); Tomita, M. [Applied Superconductivity Materials Tech. Div., Railway Technical Research Institute, 2-8-38, Hikari-cho, Kokubunji-shi, Tokyo 185-8540 (Japan)

    2013-01-15

    Highlights: ► Stacking methods for compact NMR magnet using YBCO thin films were tested. ► The stacking angles are 0°, 22.5° and 90° against the rolling direction. ► The best spatial field homogeneity was obtained in rotation angle of 22.5°. ► The maximum trapped magnetic fields of 0.4 T was obtained at 77.4 K. ► The maximum trapped magnetic fields of 0.95 T was obtained at 21 K. -- Abstract: A compact high temperature superconducting (HTS) magnet, which consists of a stack of 500 HTS thin film annuli, was constructed and tested. Each thin film annulus, manufactured by the AMSC using the Rolling Assisted Bi-axially Textured Substrate (RABiTS) method, has a square cross-section of 40 mm × 40 mm with a thickness of 80 m. It has a 25-mm center hole created by machining. This paper reports a study on the anisotropic J{sub c} issue due to the rolling procedure of the Ni substrate direction and its impact on field homogeneity. Also, three different stacking methods with rotation angles of 22.5°, 90°, and 0° against the rolling direction have been tested to study their impacts on strength, spatial homogeneity, and temporal stability of trapped fields. Finally, the 500-annulus magnet was tested at 21 K under a cryogen-free environment using a GM cryocooler. The spatial field homogeneity and temporal stability were measured at 21 K and compared with those obtained in a bath of liquid nitrogen at 77 K.

  19. Magnetic properties of thin Ni films measured by a dc SQUID-based magnetic microscope

    DEFF Research Database (Denmark)

    Snigirev, O.V.; Andreev, K.E.; Tishin, A.M.;

    1997-01-01

    We have applied a scanning HTS (high-temperature superconductor) de SQUID (superconducting quantum interference device) -based magnetic microscope to study the magnetic properties of Au/Ni/Si(100) films in the thickness range from 8 to 200 Angstrom at T = 77 K. A one-domain structure with in-plan...

  20. Substrate dependent structural and magnetic properties of pulsed laser deposited Fe3O4 thin films.

    Science.gov (United States)

    Goyal, Rajendra N; Kaur, Davinder; Pandey, Ashish K

    2010-12-01

    Nanocrystalline iron oxide thin films have been deposited on various substrates such as quartz, MgO(100), and Si(100) by pulsed laser deposition technique using excimer KrF laser (248 nm). The orientations, crystallite size and lattice parameters were studied using X-ray diffraction. The XRD results show that the films deposited on MgO and Si substrates are highly oriented and show only (400) and (311) reflections respectively. On the other hand, the orientation of the films deposited on quarts substrate changed from (311) to (400) with an increase in the substrate temperature from 400 degrees C to 600 degrees C, indicating thereby that the film growth direction is highly affected with nature of substrate and substrate temperature. The surface morphology of the deposited films was studied using Atomic Force Microscopy (AFM) and spherical ball like regular features of nanometer size grains were obtained. The magnetic properties were studied by Superconducting Quantum Interference Device (SQUID) magnetometer in the magnetic field +/- 6 Tesla. The magnetic field dependent magnetization (M-H) curves of all the Fe3O4 thin films measured at 5 K and 300 K show the ferrimagnetic nature. The electrochemical sensing of dopamine studied for these films shows that the film deposited on MgO substrate can be used as a sensing electrode.

  1. Perpendicular magnetic anisotropy in thin ferromagnetic films adjacent to high-k oxides

    Science.gov (United States)

    Xu, Meng; Bi, Chong; Rosales, Marcus; Newhouse-Illige, Ty; Almasi, Hamid; Wang, Weigang

    2015-03-01

    Perpendicular magnetic anisotropy (PMA) in thin ferromagnetic films has attracted a great deal of attention due to interesting physics and promising application in spintronic devices. The strength of PMA is often found to be strongly influenced by the adjacent heavy metal layer and oxide layer. A strong interest has emerged recently to control the PMA of these ultra-thin films by electric fields. Here we report the fabrication and characterization of perpendicularly magnetized 3d transitional metal films next to high-k oxides such as HfO2 and ZrO2. We have investigated structural, magnetic and transport properties of these films. The PMA strongly depends on the thickness of the ferromagnetic layers and the interfacial oxidation level of the bilayers. We will also discuss electric field controlled magnetic properties in these systems. This work was supported in part by NSF (ECCS-1310338) and by C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA.

  2. Perpendicular magnetic anisotropy in Mn{sub 2}CoAl thin film

    Energy Technology Data Exchange (ETDEWEB)

    Sun, N. Y.; Zhang, Y. Q.; Che, W. R.; Shan, R. [Shanghai Key Laboratory of Special Artificial Microstructure and Pohl Institute of Solid State Physics and School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Fu, H. R.; You, C. Y., E-mail: caiyinyou@xaut.edu.cn [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China)

    2016-01-15

    Heusler compound Mn{sub 2}CoAl (MCA) is attracting more attentions due to many novel properties, such as high resistance, semiconducting behavior and suggestion as a spin-gapless material with a low magnetic moment. In this work, Mn{sub 2}CoAl epitaxial thin film was prepared on MgO(100) substrate by magnetron sputtering. The transport property of the film exhibits a semiconducting-like behavior. Moreover, our research reveals that perpendicular magnetic anisotropy (PMA) can be induced in very thin Mn{sub 2}CoAl films resulting from Mn-O and Co-O bonding at Mn{sub 2}CoAl/MgO interface, which coincides with a recent theoretical prediction. PMA and low saturation magnetic moment could lead to large spin-transfer torque with low current density in principle, and thus our work may bring some unanticipated Heusler compounds into spintronics topics such as the domain wall motion and the current-induced magnetization reversal.

  3. Perpendicular magnetic anisotropy in Mn2CoAl thin film

    Directory of Open Access Journals (Sweden)

    N. Y. Sun

    2016-01-01

    Full Text Available Heusler compound Mn2CoAl (MCA is attracting more attentions due to many novel properties, such as high resistance, semiconducting behavior and suggestion as a spin-gapless material with a low magnetic moment. In this work, Mn2CoAl epitaxial thin film was prepared on MgO(100 substrate by magnetron sputtering. The transport property of the film exhibits a semiconducting-like behavior. Moreover, our research reveals that perpendicular magnetic anisotropy (PMA can be induced in very thin Mn2CoAl films resulting from Mn-O and Co-O bonding at Mn2CoAl/MgO interface, which coincides with a recent theoretical prediction. PMA and low saturation magnetic moment could lead to large spin-transfer torque with low current density in principle, and thus our work may bring some unanticipated Heusler compounds into spintronics topics such as the domain wall motion and the current-induced magnetization reversal.

  4. Defect induced modification of structural, topographical and magnetic properties of zinc ferrite thin films by swift heavy ion irradiation

    Science.gov (United States)

    Raghavan, Lisha; Joy, P. A.; Vijaykumar, B. Varma; Ramanujan, R. V.; Anantharaman, M. R.

    2017-04-01

    Swift heavy ion irradiation provides unique ways to modify physical and chemical properties of materials. In ferrites, the magnetic properties can change significantly as a result of swift heavy ion irradiation. Zinc ferrite is an antiferromagnet with a Neel temperature of 10 K and exhibits anomalous magnetic properties in the nano regime. Ion irradiation can cause amorphisation of zinc ferrite thin films; thus the role of crystallinity on magnetic properties can be examined. The influence of surface topography in these thin films can also be studied. Zinc ferrite thin films, of thickness 320 nm, prepared by RF sputtering were irradiated with 100 MeV Ag ions. Structural characterization showed amorphisation and subsequent reduction in particle size. The change in magnetic properties due to irradiation was correlated with structural and topographical effects of ion irradiation. A rough estimation of ion track radius is done from the magnetic studies.

  5. Extraordinary Hall effect in thin magnetic films and its potential for sensors, memories and magnetic logic applications

    Science.gov (United States)

    Moritz, J.; Rodmacq, B.; Auffret, S.; Dieny, B.

    2008-07-01

    We investigate the potential of the extraordinary Hall effect (EHE) in magnetic thin films with out-of-plane anisotropy for sensors, memories or logic applications. The scalability of EHE at decreasing lateral dimension has been first explored. In order for EHE to provide output voltage compatible with CMOS technology, it is shown that the longitudinal resistivity of the magnetic material must be considerably increased at decreasing size while keeping a large Hall angle. Then the EHE properties of various classes of materials with out-of-plane anisotropy ((Co/Pt) multilayers, FePt ordered alloys, rare-earth/transition metal alloys, CoSiOx and CoPtSiOx heterogeneous composites) are measured and compared in order to evaluate their potential for the envisioned applications. It is concluded that while EHE can readily be used for large devices (size > micrometres), no materials are yet available which offer suitable scalability towards the 22 nm microelectronic node.

  6. Magnetic Properties of FeNi-Based Thin Film Materials with Different Additives

    Directory of Open Access Journals (Sweden)

    Cai Liang

    2014-07-01

    Full Text Available This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B.

  7. Magnetic properties of FeNi-based thin film materials with different additives

    KAUST Repository

    Liang, C.

    2014-07-04

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B. 2014 by the authors.

  8. Magnetic properties of FeCoC thin films prepared by various sputtering methods

    Energy Technology Data Exchange (ETDEWEB)

    Edon, V; Dubourg, S [CEA, DAM, LE RIPAULT, F-37260 Monts (France); Vernieres, J; Bobo, J-F, E-mail: sebastien.dubourg@cea.fr [LNMH-CEMES-CNRS-ONERA, F-31055 Toulouse (France)

    2011-07-06

    In order to grow nanocrystallized soft magnetic thin films, FeCoC alloys were first deposited by reactive sputtering in Ar/C{sub 2}H{sub 2} plasma. This deposition process rendered it possible to incorporate a carbon content between 0 and 30 at.% into the FeCo samples. The films were then compared to FeCoC samples obtained from a Fe{sub 65}Co{sub 35}/C composite target, with an adjustable amount of C slots. Layers with soft magnetic properties were achieved when increasing the C{sub 2}H{sub 2} rate during the reactive deposition, whereas films deposited by sputtering of FeCo and C on the same target demonstrated a very high coercivity. Permeability spectra measurements (and published elsewhere) demonstrated that FeCoC prepared with acetylene is a very promising material for high-frequency magnetic devices.

  9. Ferromagnetic MnGaN thin films with perpendicular magnetic anisotropy for spintronics applications

    Science.gov (United States)

    Lee, Hwachol; Sukegawa, Hiroaki; Liu, Jun; Ohkubo, Tadakatsu; Kasai, Shinya; Mitani, Seiji; Hono, Kazuhiro

    2015-07-01

    Perpendicularly magnetized flat thin films of antiperovskite Mn67Ga24N9 were grown on an MgO(001) substrate by reactive sputtering using an argon/1% nitrogen gas mixture and a Mn70Ga30 target. The films showed a saturation magnetization of 80 -100 kA/m, an effective perpendicular magnetic anisotropy (PMA) energy of 0.1-0.2 MJ/m3, and a Curie temperature of 660-740 K. Upon increasing the N composition, the films transformed from ferromagnetic to antiferromagnetic as expected in the stoichiometric Mn3GaN phase. Point contact Andreev reflection spectroscopy revealed that the ferromagnetic MnGaN has a current spin polarization of 57%, which is comparable to D022-MnGa. These findings suggest that MnGaN is a promising PMA layer for future spintronics devices.

  10. Crossover to striped magnetic domains in Fe1-xGax magnetostrictive thin films

    Science.gov (United States)

    Barturen, M.; Rache Salles, B.; Schio, P.; Milano, J.; Butera, A.; Bustingorry, S.; Ramos, C.; de Oliveira, A. J. A.; Eddrief, M.; Lacaze, E.; Gendron, F.; Etgens, V. H.; Marangolo, M.

    2012-08-01

    We have studied the magnetic properties at room temperature of Fe1-xGax (FeGa) epitaxial thin films grown on ZnSe/GaAs(100) for 0.14≤x≤0.29 range concentration, and film thicknesses, d = 36 and 72 nm. The study was performed by means of magnetometric measurements and magnetic force microscopy scans. Increasing x promotes the loss of the four-fold magnetic-crystalline anisotropy associated to an Fe-like behavior, which is lost completely above x = 0.20. Stripe domains with rotatable anisotropy are observed even in samples in which the theoretical conditions for stripe appearance are not completely fulfilled. An unexpected "saw-tooth" stripe structure has been found under certain conditions.

  11. Electron theory of perpendicular magnetic anisotropy of Co-ferrite thin films

    Directory of Open Access Journals (Sweden)

    Jun-ichiro Inoue

    2014-02-01

    Full Text Available We develop an electron theory for the t2g electrons of Co2+ ions to clarify the perpendicular magnetic anisotropy (PMA mechanism of Co-ferrite thin films by considering the spin-orbit interaction (SOI and crystal-field (CF potentials induced by the local symmetry around the Co ions and the global tetragonal symmetry of the film. Uniaxial and in-plane MA constants Ku and K1 at 0 K, respectively, are calculated for various values of SOI and CF. We show that reasonable parameter values explain the observed PMA and that the orbital moment for the in-plane magnetization reduces to nearly half of that of the out-of-plane magnetization.

  12. Electron theory of perpendicular magnetic anisotropy of Co-ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Jun-ichiro; Yanagihara, Hideto; Kita, Eiji [Institute of Applied Physics, University of Tsukuba, Tsukuba 305-8573 (Japan); Niizeki, Tomohiko [Institute of Applied Physics, University of Tsukuba, Tsukuba 305-8573 (Japan); AIMR, Tohoku University, Sendai 980-8577 (Japan); Itoh, Hiroyoshi [Department of Pure and Applied Physics, Kansai University, Suita 564-8680 (Japan)

    2014-02-15

    We develop an electron theory for the t{sub 2g} electrons of Co{sup 2+} ions to clarify the perpendicular magnetic anisotropy (PMA) mechanism of Co-ferrite thin films by considering the spin-orbit interaction (SOI) and crystal-field (CF) potentials induced by the local symmetry around the Co ions and the global tetragonal symmetry of the film. Uniaxial and in-plane MA constants K{sub u} and K{sub 1} at 0 K, respectively, are calculated for various values of SOI and CF. We show that reasonable parameter values explain the observed PMA and that the orbital moment for the in-plane magnetization reduces to nearly half of that of the out-of-plane magnetization.

  13. Influence of modulated structure on magnetic properties of NdFeB/Co multilayer thin films

    Institute of Scientific and Technical Information of China (English)

    傅宇东; 王诗阳; 朱小硕; 方博; 闫峰

    2015-01-01

    The NdFeB/Co multilayer films were prepared by magnetron sputtering. After that, the samples were annealed at 600 °C for 20 min. The surface morphology, phase structures and magnetic properties of Mo (50 nm)/[NdFeB (100 nm)/Co(y)]×10/Mo (50 nm) thin films were researched by AFM, XRD and VSM, respectively. The results show that the films show stronger perpendicular magnetic anisotropy. When the thickness of Co layers is 10 nm, the coercivity Hc⊥ is the maximum, 295 kA/m. However, for y=10−20, the reduced remanence M/Ms of films has increased. When the thickness of Co layers is 20−30 nm, the NdFeB/Co multilayer films obtained more superior magnetic properties with M/Ms=0.95.

  14. Orientation and thickness dependence of magnetization at the interfacesof highly spin-polarized manganite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chopdekar, Rajesh V.; Arenholz, Elke; Suzuki, Y.

    2008-08-18

    We have probed the nature of magnetism at the surface of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films. The spin polarization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films is not intrinsically suppressed at all surfaces and interfaces but is highly sensitive to both the epitaxial strain state as well as the substrate orientation. Through the use of soft x-ray spectroscopy, the magnetic properties of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces have been investigated and compared to bulk magnetometry and resistivity measurements. The magnetization of (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces are more bulk-like as a function of thickness whereas the magnetization at the (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interface is suppressed significantly below a layer thickness of 20 nm. Such findings are correlated with the biaxial strain state of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films; for a given film thickness it is the tetragonal distortion of (001) La{sub 0.7}Sr{sub 0.3}MnO{sub 3} that severely impacts the magnetization, whereas the trigonal distortion for (111)-oriented films and monoclinic distortion for (110)-oriented films have less of an impact. These observations provide evidence that surface magnetization and thus spin polarization depends strongly on the crystal surface orientation as well as epitaxial strain.

  15. Statics and dynamics of zero field stable skyrmions in magnetic thin layers

    Science.gov (United States)

    Kiselev, Nikolai S.; Heo, Changhoon; Nandy, Ashis Kumar; Rasing, Theo; Blügel, Stefan

    2015-03-01

    We have developed a method which allows determining the magnetic helicity in thin films by magnetotransport measurements. A helical spin configuration occurs during magnetization reversal in exchange coupled Ni/FeF2 heterostructures. Both longitudinal and transverse components of the magnetization are concurrently detected using magnetotransport through a lithographically patterned cross junction. Small angle deviations around the well-defined unidirectional anisotropy axis reveal the change in the helicity of in-depth spin configuration. The simulations obtained using an incomplete domain wall model are in excellent agreement with the experimental data. Thus, we show that the complex spin formations in nanomagnetic systems can be studied with a lab based, well known, and rather simple experimental technique. We have developed a method which allows determining the magnetic helicity in thin films by magnetotransport measurements. A helical spin configuration occurs during magnetization reversal in exchange coupled Ni/FeF2 heterostructures. Both longitudinal and transverse components of the magnetization are concurrently detected using magnetotransport through a lithographically patterned cross junction. Small angle deviations around the well-defined unidirectional anisotropy axis reveal the change in the helicity of in-depth spin configuration. The simulations obtained using an incomplete domain wall model are in excellent agreement with the experimental data. Thus, we show that the complex spin formations in nanomagnetic systems can be studied with a lab based, well known, and rather simple experimental technique. Research supported by the Department of Energy's Office of Basic Energy Science, DMR under Grant DE FG03 87ER-45332. R.M. acknowledges funding from EU FP7-IRSES-2012 318901, MINECO FIS2013-45469 and MECD CAS12/00241.

  16. Magnetic Insulator Thin Films and Induced Magneto-Transport Effect at Normal Metal / Magnetic Insulator Interface

    OpenAIRE

    2013-01-01

    The discipline of spintronics with magnetic insulators (MI) has attracted extensive attention in both research and application interests. Yttrium iron garnet (YIG) is a ferrimagnetic insulator which is called the spin Seebeck insulator, for its supports of pure spin currents generation. Non-magnetic metals (NM) with strong spin-orbit interaction (e.g. Pd, Pt), are used as either spin current generator or detector based on the spin Hall effect (SHE) or the inverse spin Hall effect (ISHE). The ...

  17. Tailoring of in-plane magnetic anisotropy in polycrystalline cobalt thin films by external stress

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Dileep, E-mail: dkumar@csr.res.in [UGC-DAE Consortium for Scientic Research, Khandwa Road, Indore 452001 (India); Singh, Sadhana [UGC-DAE Consortium for Scientic Research, Khandwa Road, Indore 452001 (India); Vishawakarma, Pramod [School of Nanotechnology, RGPV, Bhopal 462036 (India); Dev, Arun Singh; Reddy, V.R. [UGC-DAE Consortium for Scientic Research, Khandwa Road, Indore 452001 (India); Gupta, Ajay [Amity Center for Spintronic Materials, Amity University, Sector 125, Noida 201303 (India)

    2016-11-15

    Polycrystalline Co films of nominal thickness ~180 Å were deposited on intentionally curved Si substrates. Tensile and compressive stresses of 100 MPa and 150 MPa were induced in the films by relieving the curvature. It has been found that, within the elastic limit, presence of stress leads to an in-plane magnetic anisotropy in the film and its strength increases with increasing stress. Easy axis of magnetization in the films is found to be parallel/ transverse to the compressive /tensile stresses respectively. The origin of magnetic anisotropy in the stressed films is understood in terms of magneto- elastic coupling, where the stress try to align the magnetic moments in order to minimize the magneto-elastic as well as anisotropy energy. Tensile stress is also found to be responsible for the surface smoothening of the films, which is attributed to the movement of the atoms associated with the applied stress. The present work provides a possible way to tailor the magnetic anisotropy and its direction in polycrystalline and amorphous films using external stress. - Highlights: • Tensile and compressive stresses were induced in Co films by removing the bending force from the substrates after film deposition. • Controlled external mechanical stress is found to be responsible for magnetic anisotropies in amorphous and polycrystalline thin films, where crystalline anisotropy is absent. • Tensile stress leads to surface smoothening of the polycrystalline Co films.

  18. Perpendicular magnetic anisotropy in Co{sub 3}Pt thin films

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Christian; Makarov, Denys; Brombacher, Christoph; Neupert, Katja; Kehr, Mirko; Hoyer, Walter; Albrecht, Manfred [Chemnitz University of Technology (Germany). Institute of Physics

    2010-07-01

    Binary alloys of M{sub x}Pt{sub 1-x} (M=Fe and Co) prepared as thin films tend to show a strong perpendicular magnetic anisotropy (PMA), making them good candidates for magnetic recording media or sensoric devices. The magnetic response of M{sub x}Pt{sub 1-x} films can be strongly modified by the degree of composition, film thickness, deposition temperature, and nature of substrate. Thus, chemically disordered CoPt alloys with (111) texture exhibit an unexpected PMA related to an anisotropic short-range order (SRO) effect. Here we present an investigation of structural and magnetic properties of Co{sub 3}Pt alloy films in the thickness range from 5 to 20 nm. The magnetic layers were deposited using magnetron co-sputtering on thermally oxidized Si(100) wafers. Interestingly, even when deposited at room temperature, these films reveal the presence of a strong PMA (K{sub U} = 0.6 MJ/m{sup 3}) with a full remanence in the out-of-plane direction. Furthermore, owing to the high Co content, the alloy has a rather high value of saturation magnetization of about 0.8 T. To access the structural properties of the alloy, a X-ray diffraction study was carried out. However, no superstructure peaks which might be attributed to a chemical long range order have been observed indicating that SRO is the origin for the PMA.

  19. Study of nanocrystalline thin cobalt films with perpendicular magnetic anisotropy obtained by thermal evaporation

    Science.gov (United States)

    Kozłowski, Witold; Balcerski, Józef; Szmaja, Witold

    2017-02-01

    We have performed a detailed investigation of the morphological and magnetic domain structures of nanocrystalline thin cobalt films with perpendicular magnetic anisotropy. The films were thermally evaporated at an incidence angle of 0° in a vacuum of about 10-5 mbar and possessed thicknesses in the range from 60 nm to 100 nm. The films were studied by X-ray photoelectron spectroscopy (XPS), electron diffraction of transmission electron microscopy (TEM), atomic force microscopy (AFM), magnetic force microscopy (MFM) and the Fresnel mode of TEM. The films are polycrystalline and consist of very densely packed grains with sizes at the nanometer range. The grains are roundish in shape and generally exhibit no geometric alignment. The films are mainly composed of the hexagonal close-packed (HCP) phase of cobalt and possess preferential orientation of the cobalt grains with the hexagonal axis perpendicular to the film surface. 70 nm thick films and thicker have fully perpendicular magnetization, while 60 nm thick films possess clearly dominating perpendicular magnetization component. The magnetic domain structure is in the form of stripe domains forming a maze pattern. When the film thickness increases from 60 nm to 100 nm, the average grain size increases from 28.9 nm to 31.5 nm and the average domain width increases from 79.4 nm to 98.7 nm.

  20. Spin-orbit torque-assisted switching in magnetic insulator thin films with perpendicular magnetic anisotropy

    Science.gov (United States)

    Li, Peng; Liu, Tao; Chang, Houchen; Kalitsov, Alan; Zhang, Wei; Csaba, Gyorgy; Li, Wei; Richardson, Daniel; Demann, August; Rimal, Gaurab; Dey, Himadri; Jiang, J. S.; Porod, Wolfgang; Field, Stuart B.; Tang, Jinke; Marconi, Mario C.; Hoffmann, Axel; Mryasov, Oleg; Wu, Mingzhong

    2016-09-01

    As an in-plane charge current flows in a heavy metal film with spin-orbit coupling, it produces a torque on and thereby switches the magnetization in a neighbouring ferromagnetic metal film. Such spin-orbit torque (SOT)-induced switching has been studied extensively in recent years and has shown higher efficiency than switching using conventional spin-transfer torque. Here we report the SOT-assisted switching in heavy metal/magnetic insulator systems. The experiments used a Pt/BaFe12O19 bilayer where the BaFe12O19 layer exhibits perpendicular magnetic anisotropy. As a charge current is passed through the Pt film, it produces a SOT that can control the up and down states of the remnant magnetization in the BaFe12O19 film when the film is magnetized by an in-plane magnetic field. It can reduce or increase the switching field of the BaFe12O19 film by as much as about 500 Oe when the film is switched with an out-of-plane field.

  1. Spin–orbit torque-assisted switching in magnetic insulator thin films with perpendicular magnetic anisotropy

    Science.gov (United States)

    Li, Peng; Liu, Tao; Chang, Houchen; Kalitsov, Alan; Zhang, Wei; Csaba, Gyorgy; Li, Wei; Richardson, Daniel; DeMann, August; Rimal, Gaurab; Dey, Himadri; Jiang, J. S.; Porod, Wolfgang; Field, Stuart B.; Tang, Jinke; Marconi, Mario C.; Hoffmann, Axel; Mryasov, Oleg; Wu, Mingzhong

    2016-01-01

    As an in-plane charge current flows in a heavy metal film with spin–orbit coupling, it produces a torque on and thereby switches the magnetization in a neighbouring ferromagnetic metal film. Such spin–orbit torque (SOT)-induced switching has been studied extensively in recent years and has shown higher efficiency than switching using conventional spin-transfer torque. Here we report the SOT-assisted switching in heavy metal/magnetic insulator systems. The experiments used a Pt/BaFe12O19 bilayer where the BaFe12O19 layer exhibits perpendicular magnetic anisotropy. As a charge current is passed through the Pt film, it produces a SOT that can control the up and down states of the remnant magnetization in the BaFe12O19 film when the film is magnetized by an in-plane magnetic field. It can reduce or increase the switching field of the BaFe12O19 film by as much as about 500 Oe when the film is switched with an out-of-plane field. PMID:27581060

  2. Investigating the magnetic field-dependent conductivity in magnetite thin films by modelling the magnetorefractive effect.

    Science.gov (United States)

    Kelley, Chris S; Naughton, James; Benson, Emma; Bradley, Ruth C; Lazarov, Vlado K; Thompson, Sarah M; Matthew, Jim A D

    2014-01-22

    A model of the magnetorefractive effect is developed for metallic oxides which allows the MRE to be used to study the magnetic dependence of their transport and phononic properties. This model is successfully applied to Fe3O4 and compared to experiments on a series of magnetite thin films of varying thickness (10, 18, 37, 64 and 110 nm) deposited on MgO(111) substrates. Reflection spectra were modelled as a function of film thickness, calculated from the Fresnel equations using an Fe3O4 dielectric function consisting of Drude, hopping, phononic and d-s transition conductivity processes. The reflectivity spectra of the different thickness films are reasonably reproduced by the model and reveal that the Fe3O4 18.5 μm phonon peak is shifted to a shorter wavelength in the thin films, approaching the bulk value for t > 110 nm. The MRE spectra are modelled by introducing a magnetic field dependence to the hopping and phononic terms, where previous models have considered the magnetic dependence to be on the Drude term only. In addition, the position of the Fe3O4 18.5 μm phonon peak was also found to shift in energy in the applied magnetic field by 0.05 μm. These results demonstrate the potential for using the MRE technique for probing the underlying magnetoelectronic properties of thin film oxides in a quick and non-destructive way.

  3. Tuning the magnetic properties of Fe50-xMnxPt50 thin films

    Science.gov (United States)

    Manoharan, Ezhil A.; Mankey, Gary; Hong, Yang-Ki

    2017-09-01

    The magnetic and structural properties of highly ordered (S ∼ 0.82) epitaxial Fe50-xMnxPt50 thin films were investigated. L10 Fe50-xMnxPt50 (x = 0, 6, 9, 12 and 15) thin films with a constant thickness of 45 nm were prepared by co-sputtering Fe50Pt50 and Mn50Pt50 on to MgO (100) single crystal substrate. We find a significant increase in the coercivity for FeMnPt thin films. We have shown that this increase coincides with a tetragonal distortion, while a recent first principles study of Mn doped FePt showed the sub lattice ordering of ferromagnetically aligned Mn atoms would lead to increase in magnetic anisotropy in the FeMnPt ternary alloy system with fixed Pt concentration. At x = 12 the coercivity has increased by 46.4% relative to that of Fe50Pt50 (x = 0). We attribute the increase in coercivity to the tetragonal distortion as the experimentally determined c/a ratio is larger than the expected c/a ratio for ferromagnetically ordered Mn atoms in the sublattice at the concentration x = 12. High temperature deposition and high temperature annealing was applied to achieve large coercivity in Mn doped FePt as these process lead to the observed tetragonal distortion.

  4. Exciting transition metal doped dilute magnetic thin films: MgO:Er and ZnO:Er

    Science.gov (United States)

    Ćakıcı, T.; Sarıtaş, S.; Muǧlu, G. Merhan; Yıldırım, M.

    2017-02-01

    Erbium doped MgO and doped ZnO thin films have reasonably important properties applications in spintronic devices. These films were synthesized on glass substrates by Chemical Spray Pyrolysis (CSP) method. In the literature there has been almost no report on preparation of MgO:Er dilute magnetic thin films by means of CSP. Because doped thin films show different magnetic behaviors, depending upon the type of magnetic material ions, concentration of them, synthesis route and experimental conditions, synthesized MgO:Er and ZnO:Er films were compared to thin film properties. Optical analyses of the synthesized thin films were examined spectral absorption and transmittance measurements by UV-Vis double beam spectrophotometer technique. Structural analysis of the thin films was examined by using XRD, Raman Analysis, FE-SEM, EDX and AFM techniques. Also, magnetic properties of the MgO:Er and ZnO:Er films were investigated by vibrating sample magnetometer (VSM) which show that diamagnetic behavior of the MgO:Er thin film and ferromagnetic (FM) behavior of the ZnO:Er film were is formed.

  5. Influence of the interface on the magnetic properties of NiZn ferrite thin films treated by proton irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, X.D. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Guo, D.W. [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Zhang, C.H., E-mail: c.h.zhang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Fan, X.L.; Chai, G.Z. [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Xue, D.S., E-mail: xueds@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2015-09-01

    In order to systematically investigate the influence of the interface on the magnetic properties, polycrystalline NiZn ferrite thin films were irradiated with 60 keV proton in the dose range from 5 × 10{sup 12} to 5 × 10{sup 16} ions/cm{sup 2}. A non-destructive approach by proton irradiation was found to finely adjust the magnetic properties of polycrystalline NiZn ferrite thin films such as coercivity, perpendicular magnetic anisotropy as well as the effective g value. The coercivity is about 725 Oe for high proton dose ferrite, which is twice larger than the unirradiated one. The ferromagnetic resonance measurements indicated that perpendicular magnetic anisotropy and the effective g value increase with the irradiation dose. Our finding indicates that all modifications of these magnetic properties were associated with the change of interface due to the diffusion and the stress induced by proton irradiation. The change of the effective g value is a result of lattice expansion and the decrease of the magnetic dipole interaction between the columnar grains. This work provides a feasible way to tailor the magnetic properties of thin films by ion irradiation and promotes investigations for the stability of magnetic thin film devices in space or unclear radiation environments.

  6. Thin, horizontal-plane Hall sensors for read heads in magnetic recording

    Science.gov (United States)

    Solin, S. A.; Stradling, R. A.; Thio, T.; Bennett, J. W.

    1997-10-01

    We show that thin mesoscopic read-head sensors with a vertical resolution of 0957-0233/8/10/021/img8 are advantageous for detecting magnetic fields from high-density recording media and compare such sensors constructed from narrow-gap semiconductors using the Hall bar and Corbino (giant magnetoresistance) geometries. For signal fields below a critical crossover field 0957-0233/8/10/021/img9, the Hall bar yields a larger output voltage. The maximum output voltage for a thin Hall bar detector is proportional to the maximum drift velocity of the sensor material and to its width. The maximum output voltage and power signal-to-noise ratios are calculated for thin Hall bar read-head sensors constructed from a number of polar semiconductor materials. Read heads of this type are shown to be competitive with metallic spin valve magnetoresistive read heads. We propose a simple, commercially practical procedure for the fabrication of thin Hall bar read-head sensors with high sensitivity and high spatial resolution.

  7. Crystalline structure, and magnetic and magneto-optical properties of MnSbBi thin films

    CERN Document Server

    Kang, K

    2001-01-01

    the c-axis texture and the saturation magnetisation due to less segregation of the non-magnetic phase in the annealed films. Using a thin Sb seed layer in Mn/Sb/Bi// films also results in an increase in both the c-axis texture and the saturation magnetisation. Decreasing the layer thicknesses in Mn/Bi/Sb// films results in a decrease in the grain size. By depositing the Sb layer first in Pt/Mn/Sb// and Co/Mn/Sb// films, the perpendicular c-axis texture can be kept before and after annealing. Computer simulation was carried out to investigate the relationship between the crystal structure and the magnetic properties before and after annealing. Comparing optical and MO properties of annealed Mn/Sb/Bi// and Mn/Sb// films suggests a possible origin of the peaks in Kerr spectra caused by adding Bi. This thesis reports work carried out to investigate some aspects of the crystal structure, and magnetic and magneto-optical (MO) properties in thin films of the Mn-Sb system. Reports of interesting properties and the po...

  8. Indoor allergen assessment quantified by a thin-layer electrochemical cell and magnetic beads.

    Science.gov (United States)

    Kurita, Ryoji; Yanagisawa, Hiroyuki; Niwa, Osamu

    2013-10-15

    We report the electrochemical determination of mite allergen in real house dust by using a thin layer electrochemical flow cell and magnetic beads. Der p1, which is an allergen from Dermatophagoides pteronyssinus, was immunochemically sandwiched between two dispersed monoclonal antibodies; one was modified on the surface of magnetic beads and the other was modified with alkaline phosphatase. After washing the beads, a small volume of p-aminophenol phosphate (p-APP) was added to produce p-aminophenol (p-AP). And then the p-AP concentration was measured electrochemically with a homemade electrochemical cell. The Der p1 assay was completed within 30 min and a low detection limit of 0.3 ng/mL was achieved. This is because the diffusion distance of Der p1 and the detection antibody was reduced to 22.3 μm by using dispersed magnetic beads. Only 10 min was required to complete the entire immunoreaction, and 54% of the Der p1 was confirmed to have immunoreacted in only 1 min of mixing. Furthermore, the p-APP volume could be reduced using the thin-layer electrochemical flow cell. This is advantageous in terms of concentrating p-AP, and provides a high signal-to-noise ratio measurement in a short time. We achieved a high correlation (r=0.967, p<0.001) between our assay and a conventional enzyme-linked immunosorbent assay (ELISA) for real house dust measurements.

  9. Magnetic properties of high Li doped ZnO sol–gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vettumperumal, R. [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Kalyanaraman, S., E-mail: mayura_priya2003@yahoo.co.in [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Santoshkumar, B. [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Thangavel, R. [Department of Physics, Indian School of Mines, Dhanbad (India)

    2014-02-01

    Highlights: • Ferromagnetism in high Li doped ZnO films. • Magnetic properties observed by Guoy's and VSM method. • The rod and wrinkle like structures are observed from the surface of the films. • Band gap of ZnO does not get altered by high Li doping. - Abstract: Undoped and Li doped ZnO thin films were deposited on a glass substrate using the sol–gel dip coating method. The films were prepared at 5 mol.% and 10 mol.% of Li doped ZnO at 550 °C annealing temperature and the deposited films were characterized by X-ray diffraction (XRD), microscopic studies, Gouy's method, vibrating sample magnetometer (VSM) and UV–visible spectroscopy. All the deposited thin films had a hexagonal wurtzite structure with polycrystalline grains at random. Primarily magnetic properties of pure and Li doped ZnO films were observed by Guoy's method which depicted Dia and Para magnetic behavior at room temperature. VSM measurement reveals a coercivity of 97.7 Oe in the films. An inverse relative ferromagnetism was perceived in Li doped ZnO films which had an average transmission of <90%.

  10. Structural and magnetic properties of evaporated Co/Si(100) and Co/glass thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kharmouche, A [Departement de Physique, Universite Ferhat Abbas, Setif 19000, (Algeria); Cherif, S-M [Laboratoire PMTM, Institut Galilee, Universite Paris 13, Villetaneuse, 93340 (France); Bourzami, A [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria); Layadi, A [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria); Schmerber, G [IPCMS-GEMME, UMR-CNRS, Universite Louis Pasteur, 23 rue du Loess, B.P. 43, 67034, Strasbourg, Cedex 2 (France)

    2004-09-21

    A series of Co thin films have been evaporated onto Si(100) and glass substrates. The Co thickness, t{sub Co}, ranges from 50 to 195 nm. The structural and magnetic properties have been investigated by x-ray diffraction, hysteresis curves, Brillouin light scattering and magnetic force microscopy (MFM) techniques. The Co thin films are found to be polycrystalline with (0001) texture. There is an increase of the grain size with increasing film thickness. The coercive fields range from values as low as 2 Oe in thinner films to the highest values, 2500 Oe, in 195 nm thick Co/Si films. The magnetocrystalline anisotropy field H{sub a} decreases as the thickness increases; surface and stress induced anisotropies seem to contribute to the value of H{sub a}. MFM images reveal a well-defined stripe pattern for thicker Co/Si samples. Such domains are not observed in the case of the thinner films. These so-called weak-stripe domains appear in magnetic films with a low or intermediate perpendicular anisotropy. Similar behaviour was observed in Co/glass samples, in addition, cross-tie walls were seen in thinner ones.

  11. Atomic Layer Deposition Al2O3 Thin Films in Magnetized Radio Frequency Plasma Source

    Science.gov (United States)

    Li, Xingcun; Chen, Qiang; Sang, Lijun; Yang, Lizhen; Liu, Zhongwei; Wang, Zhenduo

    Self-limiting deposition of aluminum oxide (Al2O3) thin films were accomplished by the plasma-enhanced chemical vapor deposition using trimethyl aluminum (TMA) and O2 as precursor and oxidant, respectively, where argon was kept flowing in whole deposition process as discharge and purge gas. In here we present a novel plasma source for the atomic layer deposition technology, magnetized radio frequency (RF) plasma. Difference from the commercial RF source, magnetic coils were amounted above the RF electrode, and the influence of the magnetic field strength on the deposition rate and morphology are investigated in detail. It concludes that a more than 3 Å/ purging cycle deposition rate and the good quality of ALD Al2O3 were achieved in this plasma source even without extra heating. The ultra-thin films were characterized by including Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectric spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The high deposition rates obtained at ambient temperatures were analyzed after in-situ the diagnostic of plasmas by Langmuir probe.

  12. Structural, magnetic, and transport properties of Fe-doped CoTiSb epitaxial thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sun, N. Y.; Zhang, Y. Q.; Che, W. R.; Shan, R. [Shanghai Key Laboratory of Special Artificial Microstructure and Pohl Institute of Solid State Physics and School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Qin, J., E-mail: juan-qin@staff.shu.edu.cn [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China)

    2015-11-07

    Epitaxial intrinsic and Fe-doped CoTiSb thin films with C1{sub b} structure were grown on MgO(100) substrates by magnetron sputtering. The semiconducting-like behavior in both intrinsic and Fe-doped thin films was demonstrated by temperature dependence of longitudinal resistivity. The Fe-doped CoTiSb films with a wide range of doping concentrations can maintain semiconducting-like and magnetic properties simultaneously, while the semiconducting behavior is weakening with the increasing Fe concentration. For 21 at. % Fe-doped film, low lattice magnetic moment (around 0.65 μ{sub B}) and high resistivity (larger than 800 μΩ cm) are beneficial to its application as a magnetic electrode in spintronic devices. Anomalous Hall effect of 21 at. % Fe-doped film was also investigated and its behaviors can be treated well by recent-reported anomalous Hall scaling including the contribution of spin-phonon skew scattering.

  13. Size dependent electronic and magnetic properties of ultra thin graphene nanoribbons

    Science.gov (United States)

    Kumar, Sandeep; Meenakshi; Sharma, Hitesh

    2016-09-01

    We present the results of systematic investigation into size dependent electronic and magnetic properties of ultra thin graphene nanoribbons (GNRs) of finite and infinite length using spin polarized density functional calculation. The rectangular GNRs with width up to 1.40 nm with finite (2.50 nm) and infinite length were investigated. The ultra thin GNRs are found less stable in comparison to larger GNRs with binding energy increasing with increase in the size. All GNRs have shown finite HOMO-LUMO gap which decreases oscillatory as a function of width. HOMO-LUMO gap in the Finite length armchair GNRs is in range of 0.01-0.36 eV, where as in infinite length GNR the energy gap is in the range of 0.30-1.41 eV. Zigzag GNRs have shown very small HOMO-LUMO gap in the range 50-80 meV. The zigzag GNR have shown opening of energy band gap. However, for N = 8 and 10 layers, GNRs with zigzag edges are found to be ferromagnetic. The edge C atom on zigzag edges contribute magnetic moment of 0.94 {μ }B per C atom with total magnetic moment remaining constant with increase in the width. The energy difference between ferromagnetic and anti-ferromagnetic state decreases sharply with the increase in GNR width suggesting iso-energetic behavior in larger GNRs. The results are consistent with the reported experimental results.

  14. Edge-modulated perpendicular magnetic anisotropy in [Co/Pd]n and L10-FePt thin film wires

    Science.gov (United States)

    Zhang, Jinshuo; Ho, Pin; Currivan-Incorvia, Jean Anne; Siddiqui, Saima A.; Baldo, Marc A.; Ross, Caroline A.

    2015-11-01

    Thickness modulation at the edges of nanostructured magnetic thin films is shown to have important effects on their perpendicular magnetic anisotropy. Thin film wires with tapered edges were made from [Co/Pd]20 multilayers or L10-FePt films using liftoff with a double-layer resist. The effect of edge taper on the reversal process was studied using magnetic force microscopy and micromagnetic modeling. In [Co/Pd]20, the anisotropy was lower in the tapered edge regions which switched at a lower reverse field compared to the center of the wire. The L10-FePt wires showed opposite behavior with the tapered regions exhibiting higher anisotropy.

  15. Magnetic and Electric Properties of Amorphous Co40Fe40B20 Thin Films

    Directory of Open Access Journals (Sweden)

    Yuan-Tsung Chen

    2012-01-01

    Full Text Available C40Fe40B20 was deposited on a glass substrate to a thickness (tf of between 100 Å and 500 Å. X-ray diffraction patterns (XRD indicate that C40Fe40B20 films are in an amorphous state. The plane-view microstructures and grain size distributions of CoFeB thin films are observed under a high-resolution transmission electron microscope (HRTEM. The thicker CoFeB films have larger grain size distribution than thinner CoFeB films. The saturation magnetization (Ms exhibits a size effect, meaning that Ms increases as tf increases. The magnetic remanence magnetization (Mr of CoFeB thin films are sensitive to thinner CoFeB films, and the refined grain size of thinner CoFeB films can induce ferromagnetic stronger spin exchange-coupling behavior than thicker CoFeB films, resulting in higher remanence. The highest magnetic squareness ratio (Mr/Ms of the CoFeB films occurs at thickness of 100 Å, suggesting the 100 Å of the as-deposited CoFeB film is suitable for magnetic memory application. These results also demonstrate that coercivity (Hc is increased by an increase in the width of the distribution of grain sizes. The electrical resistivity (ρ of such a film is typically higher than normally exceeding 100 μΩ cm, revealing that the amorphous phase dominates. These results are consistent with the XRD results.

  16. Structure, Magnetism, and Transport of CuCr2Se4 Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Bettinger, J.S.; Chopdekar, R.V.; Liberati, M.; Neulinger, J.R.; Chshiev, M.; Takamura, Y.; Alldredge, L.M.B.; Arenholz, E.; Idzerda,Y.U.; Stacy, A.M.; Butler, W.H.; Suzuki, Y.

    2007-04-01

    We report the successful growth of highly spin-polarized chalcogenide thin films of CuCr{sub 2}Se{sub 4}, which are promising candidates for spin-based electronic applications. We also present electronic structure calculations for CuCr{sub 2}Se{sub 4} that, together with magnetic and transport data, imply that the stoichiometric compound is a metallic ferromagnet with a relatively low density of hole-like carriers at the Fermi energy. These calculations also predict that a deficiency of Se will deplete the minority density of states at the Fermi energy perhaps leading to a half-metal. We have successfully grown thin films of CuCr{sub 2}Se{sub 4} by pulsed laser deposition on isostructural MgAl{sub 2}O{sub 4} substrates followed by an anneal in a Se-rich environment. X-ray diffraction confirms the structure of CuCr{sub 2}Se{sub 4} on MgAl{sub 2}O{sub 4} substrates as well as a secondary phase of Cr{sub 2}Se{sub 3}. X-ray absorption spectroscopy indicates that the chemical structure at the surface of the films is similar to that of bulk CuCr{sub 2}Se{sub 4} single crystals. Magnetization measurements indicate that these films saturate with a magnetic moment close to 5 {micro}{sub B} per formula unit and a T{sub c} above 400 K. X-ray magnetic circular dichroism shows that the magnetism persists to the surface of the film. Resistivity and Hall effect measurements are consistent with a p-type ferromagnetic metallic behavior and with the electronic structure calculations.

  17. Measurement setup for the magnetic penetration depth and superfluid stiffness in thin superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Lorenz; Brunner, Markus Christopher Paul; Schneider, Ina; Kronfeldner, Klaus; Strunk, Christoph [Institute for exp. and appl. Physics, University of Regensburg (Germany); Bousquet, Jessica; Bustarret, Etienne [Institut NEEL, Grenoble (France)

    2015-07-01

    A mutual inductance measurement setup has been established in order to determine the magnetic penetration depths of thin film superconductors. By measuring the variation of the mutual inductance M, the temperature dependent penetration depth can be evaluated. The setup has been characterized using thin aluminum and niobium films as a reference. Temperature dependence of λ of B-doped diamond films is determined down to 0.3 K and compared with theoretical expectations. The impact of the doping ratio B/C and film thickness on λ and T{sub c} is investigated. Correlation between the film impedance σ = σ{sub 1} - i σ{sub 2} and λ is examined.

  18. Discussion on the Split-Flow Programs of Reconstruction and Extension of Expressway and Emergent Grooming Measures%对高速公路改扩建分流方案及应急疏导方式的探讨

    Institute of Scientific and Technical Information of China (English)

    孙元鹏; 高原

    2014-01-01

    In the highway reconstruction and extension ,there are two difficulties which are split-flow and emergent grooming.Based on roadway split-flow and vehicle type split-flow,the paper sketches split-flow programs were used in the process of old road reconstruction of highway and emergent grooming measures were presented after the accident.%针对高速公路改扩建工程中的分流及应急疏导的两个难点,从道路分流和车型分流两方面简述了高速公路在旧路改造过程中曾用到的分流方案,以及介绍了发生事故后应急疏导的方法。

  19. Structure and magnetization in CoPd thin films and nanocontacts

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Caitlin, E-mail: c.morgan@fz-juelich.de [Peter Gruenberg Institut, Forschungszentrum Juelich (Germany); JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany); Schmalbuch, Klaus [JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany); Physikalisches Institut, RWTH Aachen University, Otto-Blumenthal-Strasse, 52074 Aachen (Germany); Garcia-Sanchez, Felipe [Peter Gruenberg Institut, Forschungszentrum Juelich (Germany); JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany); Schneider, Claus M. [Peter Gruenberg Institut, Forschungszentrum Juelich (Germany); JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany); Fakultaet f. Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universitaet Duisburg-Essen, D-47048 Duisburg (Germany); Meyer, Carola [Peter Gruenberg Institut, Forschungszentrum Juelich (Germany); JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany)

    2013-01-15

    We present results showing the structural and magnetic properties of MBE-grown extended films and nanostructured elements of various CoPd alloys. X-ray diffraction studies show that the thin films are polycrystalline, yet exhibit a strong preferential growth orientation along the (111) direction. Magnetic force microscopy and SQUID are used to gain an understanding of the magnetic behavior of the CoPd system with respect to competing anisotropy contributions, based on temperature-dependent SQUID data, collected between 4 and 300 K. The idea and potential implications of using CoPd as a contact material to achieve spin injection in carbon nanotube-based devices is discussed. - Highlights: Black-Right-Pointing-Pointer In-plane magnetization of CoPd films increases with added Co content. Black-Right-Pointing-Pointer Quasi single-domain nanostructures of Co{sub 50}Pd{sub 50} exhibit almost no OOP component. Black-Right-Pointing-Pointer Nanostructures exhibit decrease in coercive field with initial temperature decrease. Black-Right-Pointing-Pointer Magnetic behavior is influenced by the anti-FM oxide and magnetoelastic effect.

  20. Structural, mechanical, and magnetic properties of GaFe{sub 3}N thin films

    Energy Technology Data Exchange (ETDEWEB)

    Junaid, Muhammad, E-mail: junaid@mch.rwth-aachen.de; Music, Denis, E-mail: music@mch.rwth-aachen.de; Hans, Marcus; Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Scholz, Tanja; Dronskowski, Richard [Institute of Inorganic Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Primetzhofer, Daniel [Department of Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, S-75120 Uppsala (Sweden)

    2016-07-15

    Using the density-functional theory, the structural, mechanical, and magnetic properties were investigated for different GaFe{sub 3}N configurations: ferromagnetic, ferrimagnetic, paramagnetic, and nonmagnetic. Ferrimagnetic and high-spin ferromagnetic states exhibit the lowest energy and are the competing ground states as the total energy difference is 0.3 meV/atom only. All theoretically predicted values could be fully confirmed by experiments. For this, the authors synthesized phase pure, homogeneous, and continuous GaFe{sub 3}N films by combinatorial reactive direct current magnetron sputtering. Despite the low melting point of gallium, the authors succeeded in the growth of GaFe{sub 3}N films at a temperature of 500 °C. Those thin films exhibit a lattice parameter of 3.794 Å and an elastic modulus of 226 ± 20 GPa. Magnetic susceptibility measurements evidence a magnetic phase transitions at 8.0 ± 0.1 K. The nearly saturated magnetic moment at ±5 T is about 1.6 μB/Fe and is close to the theoretically determined magnetic moment for a ferrimagnetic ordering (1.72 μB/Fe).

  1. Spin Hall magnetoresistance at the interface between platinum and cobalt ferrite thin films with large magnetic anisotropy

    Directory of Open Access Journals (Sweden)

    Takeshi Tainosho

    2017-05-01

    Full Text Available The recently discovered spin Hall magnetoresistance (SMR effect is a useful means to obtain information on the magnetization process at the interface between a nonmagnetic metal and ferromagnetic insulators. We report the SMR measurements at the interface between platinum and cobalt ferrite thin films for samples with two different preferential directions of magnetization (out-of-plane and in-plane. The directional difference of the magnetic easy axis does not seem to influence the value of SMR.

  2. Heat assisted magnetic probe recording onto a thin film with perpendicular magnetic anisotropy

    NARCIS (Netherlands)

    Onoue, T.; Siekman, M.H.; Abelmann, L.; Lodder, J.C.

    2008-01-01

    The possibility of magnetic probe recording into a continuous perpendicular medium is discussed. By applying a current from the tip to the medium, a very localized area can be heated and bits as small as 80 nm in diameter could be written. This value is close to the calculated minimum diameter of re

  3. Highly-oriented molecular arrangements and enhanced magnetic interactions in thin films of CoTTDPz using PTCDA templates.

    Science.gov (United States)

    Eguchi, Keitaro; Nanjo, Chihiro; Awaga, Kunio; Tseng, Hsiang-Han; Robaschik, Peter; Heutz, Sandrine

    2016-07-14

    In the present work, the templating effect of thin layers of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) on the growth of cobalt tetrakis(thiadiazole)porphyrazine (CoTTDPz) thin films was examined. X-ray diffraction and optical absorption spectra indicate that while CoTTDPz forms amorphous thin films on the bare substrates, it forms crystalline thin films on the PTCDA templates, in which the molecular planes of CoTTDPz are considered to be parallel to the substrates. Magnetic measurements reveal a significantly enhanced antiferromagnetic interaction of CoTTDPz in the templated thin films, with values reaching over 13 K. The ability to generate crystalline films and to control their orientation using molecular templates is an important strategy in the fields of organic electronics and spintronics in order to tailor the physical properties of organic thin films to suit their intended application.

  4. Low-field microwave magnetic permeability on FeSiBNbCu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Viegas, A.D.C. [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil)]. E-mail: adcviegas@fisica.ufsc.br; Santi, L. [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Correa, M.A. [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Silva, R.B. da [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Andrade, A.M.H. de [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Sommer, R.L. [Centro Brasileiro de Pesquisas Fisicas-CBPF, Rio de Janeiro (Brazil)

    2006-10-01

    This work presents the dynamic and static magnetic properties of an 85 nm-thick amorphous thin film precursor of the well-known Finemet material, deposited by RF sputtering. Hysteresis evidences in-plane isotropic properties that are distinguished as contributions of hard and soft axis simultaneously. High-frequency permeability measurements were performed by using the network inductive method in the frequency range 100 kHz-1.8 GHz. The low-field FMR relation dispersion obtained from the permeability spectra shows peculiar properties, from which the effects of stress-induced anisotropy are discussed.

  5. MAGNETIC EXCHANGE-COUPLING IN CoPt/Co BILAYER THIN FILMS

    Energy Technology Data Exchange (ETDEWEB)

    KIM,J.; BARMAK,K.; LEWIS,L.H.; CREW,D.C.; WELCH,D.O.

    1999-04-05

    Thin film CoPt/Co bilayers have been prepared as a model system to investigate the relationship between microstructure and exchange coupling in two-phase hard/soft composite magnets. CoPt films, with a thickness of 25 nm, were sputter-deposited from a nearly equiatomic alloy target onto oxidized Si wafers. The films were subsequently annealed at 700 C and fully transformed from the FCC phase to the magnetically hard, ordered L1{sub 0} phase. The coercivity of the films increased rapidly with annealing time until it reached a plateau at approximately 9.5 kOe. Fully-ordered CoPt films were then used as substrates for deposition of Co layers, with thicknesses in the range of 2.8--225 nm, in order to produce the hard/soft composite bilayers. As predicted by theory, the magnetic coherency between the soft Co phase and the hard, ordered CoPt phase decreased as the thickness of the soft phase increased. This decrease in coupling was clearly seen in the magnetic hysteresis loops of the bilayers. At small thicknesses of Co (a few nanometers), the shape of the loop was one of a uniform material showing no indication of the presence of two phases with extremely different coercivities. At larger Co thicknesses, constricted loops, i.e., ones showing the presence of a mixture of two ferromagnetic phases of different hardnesses, were obtained. The magnetic exchange present in the bilayer samples was qualitatively analyzed using magnetic recoil curves and the dependence of exchange coupling on the soft phase dimension in the bilayer hard/soft composite magnet films is discussed.

  6. Weakly Nonlinear Stability Analysis of a Thin Magnetic Fluid during Spin Coating

    Directory of Open Access Journals (Sweden)

    Cha'o-Kuang Chen

    2010-01-01

    Full Text Available This paper investigates the stability of a thin electrically conductive fluid under an applied uniform magnetic filed during spin coating. A generalized nonlinear kinematic model is derived by the long-wave perturbation method to represent the physical system. After linearizing the nonlinear evolution equation, the method of normal mode is applied to study the linear stability. Weakly nonlinear dynamics of film flow is studied by the multiple scales method. The Ginzburg-Landau equation is determined to discuss the necessary conditions of the various critical flow states, namely, subcritical stability, subcritical instability, supercritical stability, and supercritical explosion. The study reveals that the rotation number and the radius of the rotating circular disk generate similar destabilizing effects but the Hartmann number gives a stabilizing effect. Moreover, the optimum conditions can be found to alter stability of the film flow by controlling the applied magnetic field.

  7. Optically transparent magnetic and electrically conductive Fe-Cr-Zr ultra-thin films

    Energy Technology Data Exchange (ETDEWEB)

    Louzguine-Luzgin, D.V.; Ketov, S.V.; Mizukami, S. [Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai (Japan); Orava, J. [Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai (Japan); Department of Materials Science and Metallurgy, University of Cambridge (United Kingdom)

    2014-05-15

    The transparent magnetic thin films having a nominal composition of Fe{sub 75}Cr{sub 15}Zr{sub 10} and containing nanocrystalline BCC Fe particles embedded in a metallic glassy matrix were deposited by a magnetron sputtering technique. The nanoparticles were homogeneously distributed in the glassy matrix, which results in the appearance of ferromagnetic properties. The phase composition and microstructure of the films were examined by X-ray diffractometry and scanning electron microscopy equipped with EDX spectroscopy. The magneto-optical properties of the obtained films were also studied by magnetic circular dichroism (MCD) method. The material obtained possesses three key properties: it is optically transparent in the visible-light range as well as electrically conductive and it shows ferromagnetism, which all of these are often mutually alternative. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Magnetic properties of ZnO:Cu thin films prepared by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhuo Shiyi; Xiong Yuying; Gu Min, E-mail: xiongyy@scnu.edu.c [Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China)

    2009-05-01

    ZnO films and ZnO:Cu diluted magnetic semiconductor films were prepared by radio frequency magnetron sputtering on Si (111) substrates, with targets of ZnO and Zn{sub 0.99}Cu{sub 0.01}O, respectively. The plasma emission spectra were analyzed by using a grating monochromator during sputtering. The X-ray photoelectron spectroscopy measurements indicate the existence of Zni defect in the films, and the valence state of Cu is 1+. The X-ray diffraction measurements indicate that the thin films have a hexagonal wurtzite structure and have a preferred orientation along the c-axis. The vibrating sample magnetometer measurements indicate that the sample is ferromagnetic at room temperature, and the origin of the magnetic behavior of the samples is discussed.

  9. Spin orientation driven static and dynamic magnetic process in amorphous FeCoBSi thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Peiheng; Luo, Xiaojia; Zhang, Li; Lu, Haipeng; Xie, Jianliang; Deng, Longjiang [State Key Laboratory of Electronic Thin Film and Integrated Devices, National Engineering Research Center of Electromagnetic Radiation Control Materials, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-06-07

    The spin orientation dependence of magnetic hysteresis and microwave ferromagnetic resonance data are investigated in FeCoBSi amorphous thin films. Demagnetization effect allows the weak interface-rooted out-of-plane anisotropy to build up local spin orientation domains under the dominant in-plane anisotropy. As a result, two phase magnetization reversal and double-peak ferromagnetic resonance traces with varying damping behavior are observed. Due to the distribution of in-plane and out-of-plane spin orientations, the ferromagnetic resonance bandwidth has been extensively expanded with the full width at half maximum increased from 1.2 GHz to 3.5 GHz.

  10. GALVANIC MAGNETIC PROPERTIES OF BISMUTH THIN FILMS DOPED WITH TELLURIUM MADE BY THERMAL VACUUM EVAPORATION

    Directory of Open Access Journals (Sweden)

    V. A. Komarov

    2013-01-01

    Full Text Available The influence of n-type impurity of tellurium (concentration range from 0.005 atomic % Te to 0.15 atomic % Te on galvanic magnetic properties (resistivity, magnetic resistance and Hall constant of Bi thin films with various thicknesses was studied. The properties were measured in temperature range from 77 to 300 K. It was established that the classical size effect in the films is significant and decreases with higher concentration of Te impurity. The analysis of experimental results was carried out in approximation of the law of Jones-Schoenberg dispersion for Bi films doped with tellurium. Calculation of concentration and mobility of charge carriers in the studied films was made.

  11. High-Spatial-Resolution Monitoring of Strong Magnetic Field using Rb vapor Nanometric-Thin Cell

    CERN Document Server

    Hakhumyan, G; Pashayan-Leroy, Y; Sarkisyan, D; Auzinsh, M

    2011-01-01

    We have implemented the so-called $\\lambda$-Zeeman technique (LZT) to investigate individual hyperfine transitions between Zeeman sublevels of the Rb atoms in a strong external magnetic field $B$ in the range of $2500 - 5000$ G (recently it was established that LZT is very convenient for the range of $10 - 2500$ G). Atoms are confined in a nanometric thin cell (NTC) with the thickness $L = \\lambda$, where $\\lambda$ is the resonant wavelength 794 nm for Rb $D_1$ line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field with the frequency positions and transition probabilities depending on the $B$-field. Possible applications are described, such as magnetometers with nanometric local spatial resolution and tunable atomic frequency references.

  12. High-spatial-resolution monitoring of strong magnetic field using Rb vapor nanometric-thin cell

    Science.gov (United States)

    Hakhumyan, G.; Leroy, C.; Pashayan-Leroy, Y.; Sarkisyan, D.; Auzinsh, M.

    2011-08-01

    We have implemented the so-called λ-Zeeman technique (LZT) to investigate individual hyperfine transitions between Zeeman sublevels of the Rb atoms in a strong external magnetic field B in the range of 2500 - 5000 G (recently it was established that LZT is very convenient for the range of 10 - 2500 G). Atoms are confined in a nanometric thin cell (NTC) with the thickness L = λ, where λ is the resonant wavelength 794 nm for Rb D 1 line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field with the frequency positions and transition probabilities depending on the B-field. Possible applications are described, such as magnetometers with nanometric local spatial resolution and tunable atomic frequency references.

  13. Influence of Magnetic Annealing on Properties of SmFe Thin Films

    Institute of Scientific and Technical Information of China (English)

    Wang Lei; Du Zhaofu; Zhao Dongliang

    2007-01-01

    SmFe thin films were prepared by DC magnetron sputtering at room temperature and 300 ℃. The influence of magnetic annealing temperature on the phase structure and magnetic properties was investigated. Results showed that thermal sputtering followed by a heat treatment process helped to obtain a structure with a relatively large fraction of SmFe2. Residual phases observed were α-Fe, Sm2O3, and unknown phases. During the annealing treatment, the intrinsic compressive stress in SmFe films was relieved and could become tensile at higher annealing temperatures. The degree of in-plane anisotropy weakened, and furthermore, the anisotropy transformed into out-of-plane anisotropy.

  14. Axisymmetric absorption of p modes by an ensemble of thin, magnetic-flux tubes

    Energy Technology Data Exchange (ETDEWEB)

    Jain, R; Gascoyne, A [Department of Applied Mathematics, University of Sheffield (United Kingdom); Hindman, B W, E-mail: R.Jain@sheffield.ac.uk [JILA, University of Colorado at Boulder (United States)

    2011-01-01

    The buffeting action of the solar acoustic waves (p modes) on magnetic fibrils excites magnetohydrodynamic (MHD) tube waves. We model these fibrils as axisymmetric, untwisted, vertically oriented, thin, magnetic-flux tubes. The MHD tube waves propagate along the length of the tube and carry energy away from the p-mode cavity creating a source of p-mode absorption. We calculate the absorption arising from the excitation of sausage MHD waves within a model plage composed of many flux tubes with differing plasma properties. We find that for a collection of tubes with normally distributed plasma parameters {beta}, the macroscopic absorption coefficient of the collection effectively depends on only the mean value of {beta}.

  15. Magnetically induced nonvolatile magnetoresistance and resistance memory effect in phase-separated manganite thin films

    Science.gov (United States)

    Li, Qian; Cao, Qingqi; Wang, Dunhui; Du, Youwei

    2017-03-01

    We report the observation of magnetically induced resistance memory effect in a typical electronic phase-separated manganite La5/8‑x Pr x Ca3/8MnO3 (x  =  0.3) thin film. In the hysteresis region of metal-to-insulator transition, the resistance exhibits a sharp drop with the application of magnetic field and maintains the low resistance state after the removal of field, showing a nonvolatile magnetoresistance effect. The high resistance state can be recovered until the temperature is warmed. More explicit measurements at the hysteresis region exhibit the non-volatility and irreversibility of magnetoresistance, which can be ascribed to the percolative feature in the electronic phase-separated manganite. The origin and potential applications of these interesting effects are discussed.

  16. Modeling thermally activated domain wall dynamics in thin magnetic strips with disorder

    Energy Technology Data Exchange (ETDEWEB)

    Laurson, L; Mughal, A; Serpico, C; Durin, G; Zapperi, S, E-mail: lasse.laurson@gmail.com [ISI Foundation, Torino (Italy)

    2011-04-01

    We study the effect of disorder and temperature on the field-driven dynamics of a transverse domain wall occurring in thin and narrow magnetic strips made of a soft magnetic material such as permalloy. Motivated by a micromagnetic description of such a domain wall, we construct a model based on two coupled flexible lines enclosing the domain wall transition region, capturing both the finite width and the characteristic V-shape of the wall. Disorder is included via randomly distributed pinning centers interacting with the two lines. We study the field-driven dynamics of the domain wall in disordered strips in a finite temperature, and compare our findings to experimental observations of stochastic domain wall dynamics.

  17. Magnetic properties of ZnO:Cu thin films prepared by RF magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    Zhuo Shiyi; Xiong Yuying; Gu Min

    2009-01-01

    ZnO films and ZnO:Cu diluted magnetic semiconductor films were prepared by radio frequency magnetron sputtering on Si (111) substrates, with targets of ZnO and Zn0.99Cu0.01 O, respectively. The plasma emission spectra were analyzed by using a grating monochromator during sputtering. The X-ray photoelectron spectroscopy measurements indicate the existence of Zni defect in the films, and the valence state of Cu is 1. The X-ray diffraction measurements indicate that the thin films have a hexagonal wurtzite structure and have a preferred orientation along the c-axis. The vibrating sample magnetometer measurements indicate that the sample is ferromagnetic at room temperature, and the origin of the magnetic behavior of the samples is discussed.

  18. Field-dependent perpendicular magnetic anisotropy in CoFeB thin films

    Energy Technology Data Exchange (ETDEWEB)

    Barsukov, I., E-mail: ibarsuko@uci.edu; Krivorotov, I. N. [Physics and Astronomy, University of California, Irvine, California 92697 (United States); Fu, Yu [INAC/CEA, Grenoble, 17 avenue des Martyrs, Grenoble 38054 (France); Fakultät für Physik and Center for Nanointegration (CeNIDE), Universität Duisburg-Essen, Duisburg 47048 (Germany); Gonçalves, A. M.; Sampaio, L. C. [Physics and Astronomy, University of California, Irvine, California 92697 (United States); Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Rio de Janeiro 22.290-180, RJ (Brazil); Spasova, M.; Farle, M. [Fakultät für Physik and Center for Nanointegration (CeNIDE), Universität Duisburg-Essen, Duisburg 47048 (Germany); Arias, R. E. [Departamento de Física, FCFM, Universidad de Chile, Casilla 487-3, Santiago (Chile)

    2014-10-13

    We report ferromagnetic resonance measurements of perpendicular magnetic anisotropy in thin films of Ta/Co{sub 20}Fe{sub 60}B{sub 20}/MgO as a function of the Co{sub 20}Fe{sub 60}B{sub 20} layer thickness. The first and second order anisotropy terms show unexpectedly strong dependence on the external magnetic field applied to the system during the measurements. We propose strong interfacial spin pinning as a possible origin of the field-dependent anisotropy. Our results imply that high-field anisotropy measurements cannot be directly used for quantitative evaluation of zero-field performance parameters of CoFeB-based devices such as spin torque memory.

  19. Complex high-frequency magnetization dynamics and magnetoimpedance in thin films

    Energy Technology Data Exchange (ETDEWEB)

    Silva, R.B. da [Departamento de Fisica, CCNE, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS (Brazil)]. E-mail: rbarreto1975@gmail.com; Viegas, A.D.C. [Departamento de Fisica, CCNE, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS (Brazil); Correa, M.A. [Departamento de Fisica, CCNE, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS (Brazil); Andrade, A.M.H. de [Departamento de Fisica, CCNE, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS (Brazil); Sommer, R.L. [Centro Brasileiro de Pesquisas Fisicas-CBPF, Rua Dr. Xavier Sigaud 150, Urca, 22290-180, Rio de Janeiro, RJ (Brazil)

    2006-10-01

    High-frequency differential magnetic permeability and magnetoimpedance measurements were performed in Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9} as-made and annealed thin films at frequencies up to 1.8 GHz. The results show complex dynamical properties characterized by multiple ferromagnetic resonance modes at relatively low frequencies for the amorphous as-made sample. After the thermal treatments, the resonance frequencies increase drastically exceeding the upper limit of 1.8 GHz for our equipment. This increase can possibly associated to higher local magnetic fields that are, in turn, associated to the formation of nanocrystalline grains randomly oriented.

  20. Magnetic domain structure in thin CoPt perpendicular magnetic anisotropy films

    Directory of Open Access Journals (Sweden)

    Komine T.

    2013-01-01

    Full Text Available The relation between thickness and domain structure of Co80Pt20 perpendicular magnetic anisotropy films was investigated through experiments and micromagnetic simulation. The films with thickness over 10 nm exhibited clear maze domain structure, while for the films thinner than 10 nm the domain structure abruptly changed from maze domain to irregular and large domain as the thickness became thinner. The irregular domain had narrower domain wall width than maze domain.

  1. Influence of antiferromagnetic FeMn on magnetic properties of perpendicular magnetic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Feng Chun; Li Baohe; Teng Jiao; Jiang Yong [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu Guanghua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)], E-mail: ghyu@mater.ustb.edu.cn

    2009-02-27

    We studied the influence of an anitferromagnetic FeMn layer on perpendicular magnetic anisotropy (PMA) and perpendicular coercivity (H{sub C}-perpendicular ) of the CoCr/Pt multilayers and found that both PMA and H{sub C}-perpendicular can be enhanced by the FeMn layer. We observed an obvious exchange coupling between FeMn and CoCr/Pt multilayers which enhances PMA and may increase the density of pinning sites that can pin the domain wall of ferromagnetic layers and lifts up energy barrier during the propagation of domain walls. This leads to the enhancement of H{sub C}-perpendicular . Moreover, X-ray diffraction results shows that the (111) texture of the FeMn layer enhances that of the CoCr/Pt multilayers, leading to the increase of PMA and H{sub C}-perpendicular as well. This result is of great significance on improving magnetic properties of perpendicular magnetic recording media by using an antiferromagnetic manganese alloy.

  2. Magnetic anisotropy of Co thin films: Playing with the shadowing effect, magnetic field and substrate spinning

    Science.gov (United States)

    Bertelli, T. P.; Bueno, T. E. P.; Krohling, A. C.; Silva, B. C.; Rodríguez-Suárez, R. L.; Nascimento, V. P.; Paniago, R.; Krambrock, K.; Larica, C.; Passamani, E. C.

    2017-03-01

    The shape and magneto-crystalline anisotropies of 10 nm thick Co sputtered films have shown to be dependent on the oblique deposition angle (αi), the angular velocity of the substrate-holder (ωS) and the applied magnetic field (H0) during the deposition. Oblique deposition geometry is natural in our sputtering setup, being α equal to 22° at the edge of 4 in. sample-holder and 32° at its central part. X-ray diffraction analysis has evidenced a (111) texturized fcc structure for all films. Ferromagnetic resonance has shown that samples prepared under H0 of 250 Oe present dominantly the uniaxial HU field contribution independent of the ωS-value, however its magnitude depends on αi. For a non-magnetic holder, Co films show a mixture of twofold (uniaxial) with fourfold (cubic) in-plane magnetic anisotropies. The fourfold contribution is small and it is not influenced by αi or ωS within the experimental error, while the dominant twofold contribution, which is governed by the shadowing effect, is reduced for higher ωS and for samples positioned at the center of the sample-holder. In addition, the intrinsic isotropic Gilbert damping dominates the relaxation process, which is followed by anisotropic twofold scattering mechanism due to stripes and defects, interestingly not influenced by the substrate rotation during depositions.

  3. Levitation force and magnetization in bulk and thin film high T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Riise, A.B

    1998-04-01

    The authors present high-resolution measurements of the repulsive vertical force and its associated stiffness between a Nd-B-Fe magnet and a YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} superconductor in cylindrical geometry. The results are compared with theoretical predictions. The calculations are based on a model in which the superconductor is assumed to be either a sintered granular material or consisting of grains embedded in a nonactive matrix so that only intragranular currents are important. The critical state model is applied to each grain individually and closed form expressions for both vertical force F{sub z} and stiffness are obtained in a configuration with cylindrical symmetry. The model explains all features of the experimental results in a consistent way. A good quantitative agreement has been obtained using only three adjustable parameters. Several central aspects of the phenomenon of magnetic levitation with high-T{sub c} superconductors are presented. High-resolution measurements are made of the repulsive vertical force and its associated stiffness as well as the horizontal stabilizing force and the stiffness governing lateral vibrations. The results obtained at 77 K using a granular YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} sample and Nd-Fe-B magnet in a rectangular levitation configuration are compared with theoretical predictions. The calculations, which are based on the critical state model with the assumption that it applies to the grins individually, give closed-form expressions for all the measured quantities. It is concluded that the present model explains all features of the observations in a consistent way. Using only three adjustable parameters a good agreement exists also at a quantitative level. Experimental studies and theoretical modelling of the levitation force on a permanent magnet placed above a superconducting thin film are offered. It is shown that measurements of the levitation force is a simple and precise method to determine the

  4. Growth of perpendicularly magnetized thin films on a polymer buffer and voltage-induced change of magnetic anisotropy at the MgO|CoFeB interface

    Directory of Open Access Journals (Sweden)

    D. D. Lam

    2015-06-01

    Full Text Available We show that perpendicularly magnetized thin films can be grown onto polyimide, a potentially flexible substrate. With polar Kerr magnetometry, we demonstrate that the coercive field of CoFeB thin film can be modulated by applying a back gate voltage. Our proposed multi-layered structure is suitable for surface-sensitive measurements of the voltage-induced change in anisotropy, and could be used to realize flexible spintronics devices.

  5. Unconventional magnetization of Fe3O4 thin film grown on amorphous SiO2 substrate

    Directory of Open Access Journals (Sweden)

    Jia-Xin Yin

    2016-06-01

    Full Text Available High quality single crystal Fe3O4 thin films with (111 orientation had been prepared on amorphous SiO2 substrate by pulsed laser deposition. The magnetization properties of the films are found to be unconventional. The Verwey transition temperature derived from the magnetization jump is around 140K, which is higher than the bulk value and it can be slightly suppressed by out-plane magnetic field; the out-of-plane magnetization, which is unexpectedly higher than the in-plane value, is also significantly increased as compared with the bulk value. Our findings highlight the unusual magnetization of Fe3O4 thin film grown on the amorphous SiO2 substrate.

  6. Changes in the Metastability of the Midlatitude Southern Hemisphere Circulation and the Utility of Nonstationary Cluster Analysis and Split-Flow Blocking Indices as Diagnostic Tools

    Science.gov (United States)

    O'Kane, Terence; Risbey, James; Franzke, Christian; Horenko, Illia; Monselesan, Didier

    2013-04-01

    The authors examine changes in the metastability of the Southern Hemisphere 500-hPa circulation using both cluster analysis techniques and split-flow blocking indices. The cluster methodology is a purely datadriven approach for parameterization whereby a multiscale approximation to nonstationary dynamical processes is achieved through optimal sequences of locally stationary fast vector autoregressive factor (VARX) processes and some slow (or persistent) hidden process switching between them. Comparison is made with blocking indices commonly used in weather forecasting and climate analysis to identify dynamically relevant metastable regimes in the 500-hPa circulation in both reanalysis and Atmospheric Model Intercomparison Project (AMIP) model datasets. The analysis characterizes the metastable regime in both reanalysis and model datasets prior to 1978 as positive and negative phases of a hemispheric midlatitude blocking state with the southern annular mode (SAM) associated with a transition state. Post 1978, the SAM emerges as a true metastable state replacing the negative phase of the hemispheric blocking pattern. The hidden state frequency of occurrences exhibits strong trends. The blocking pattern dominates in the early 1980s then gradually decreases. There is a corresponding increase in the SAM frequency of occurrence. This trend is largely evident in the reanalysis summer and spring but was not evident in the AMIP dataset. Further comparison with the split-flow blocking indices reveals a superficial correspondence between the cluster hidden state frequency of occurrences and split-flow indices. Examination of composite states shows that the blocking indices capture splitting of the zonal flow whereas the cluster composites reflect coherent block AU1 formation. Differences in blocking climatologies from the respective methods are discussed.

  7. Magnetic properties of ultra thin epitaxial Fe films on GaAs(001)

    Energy Technology Data Exchange (ETDEWEB)

    Morton, S A; Tobin, J G; Spangenberg, M; Neal, J R; Shen, T H; Waddill, G D; Matthew, J D; Greig, D; Malins, A R; Seddon, E A; Hopkinson, M

    2003-10-02

    The magnetic properties of epitaxial Fe films on GaAs in the range of the first few monolayers have been the subject of a considerable number of investigations in recent years. The absence of magnetic signatures at room temperature has been attributed to the existence of a magnetic ''dead'' layer as well as superparamagnetism. By examining the temperature dependence of the magnetic linear dichroism of the Fe core level photoelectrons, we found that these ''non-ferromagnetic'' layers had in fact a Curie temperature, T{sub c}, substantially lower than room temperature, e.g., a T{sub c} of about 240K for thin films of a nominal thickness of 0.9 nm. The values of Curie temperature were sensitive to the initial GaAs substrate conditions and the thickness of the Fe over-layer with a layer of thickness of 1.25 nm showing a T{sub c} above room temperature. The data suggest that the ultrathin Fe films on GaAs(001) are ferromagnetic, although a weaker exchange interaction in the films lead to a substantial reduction in Curie temperature.

  8. Dynamic origin of segment magnetization reversal in thin-film Penrose tilings

    Science.gov (United States)

    Montoncello, F.; Giovannini, L.; Farmer, B.; De Long, L.

    2017-02-01

    We investigate the low-frequency spin wave dynamics involved in the magnetization reversal of a Penrose P2 tiling using the dynamical matrix method. This system consists of a two-dimensional, connected wire network of elongated thin-film segments, whose complete reversal occurs as a cascade of successive local segment reversals. Using soft mode theory, we interpret the reversal of an individual segment as a first order magnetic transition, in which magnetization curve of the system suffers a small discontinuity. Near this discontinuity a specific mode of the spin wave spectrum goes soft (i.e., its frequency goes to zero), triggering a local instability of the magnetization. We show that this mode is localized, and is at the origin of the local reversal. We discuss the correlation of the mode spatial profile with the ;reversal mechanism;, which is the passage of a domain wall through the segment. This process differs from reversal in periodic square or honeycomb artificial spin ices, where a cascade of reversing segments (e.g., ;Dirac string;) follows an extended (though irregular) path across the sample; here the spatial distribution of successive segment reversals is discontinuous, but strictly associated with the area where a soft mode is localized. The migration of the localization area across the P2 tiling (during reversal in decreasing applied fields) depends on changes in the internal effective field map. We discuss these results in the context of spin wave localization due to the unique topology of the P2 tiling.

  9. Observations of Thin Current Sheets in the Solar Wind and Their Role in Magnetic Energy Dissipation

    Science.gov (United States)

    Perri, S.; Goldstein, M. L.; Dorelli, J.; Sahraoui, F.; Gurgiolo, C. A.; Karimabadi, H.; Mozer, F.; Wendel, D. E.; TenBarge, J.; Roytershteyn, V.

    2013-12-01

    A recent analysis of 450 vec/s resolution data from the STAFF search-coil magnetometer on board Cluster has revealed, for the first time, the presence of thin current sheets and discontinuities from the proton Larmor scale down to the electron Larmor scale in the solar wind. This is in the range of scales where a cascade of energy consistent with highly oblique kinetic Alfvénic fluctuations (KAW), eventually dissipated by electron Landau damping, has been detected. The current sheets have been found to have a size between 20-200 km, indicating that they are very localized. We will compare the observations with results coming from 2D Hall MHD, Gyrokinetic, and full Particle-in-Cell turbulence simulations. Preliminary work has highlighted promising qualitative agreement between the properties of the structures observed in the Cluster data and the current sheets generated in the simulations. With the aim of investigating the role played by those structures in dissipating the magnetic energy in the solar wind, E●J has been computed within each magnetic discontinuity. This has been made possible via a combined analysis of both STAFF-SC magnetic field data and the electric field data from the Electric Fields and Wave instrument (EFW). We describe procedures used to reduce the noise in the EFW data. The results obtained represent an effort to clarify the processes involved in the dissipation of magnetic energy in the solar wind.

  10. Structural Control of Magnetic Anisotropy in a Multiferroic EuTiO3 Thin Film

    Science.gov (United States)

    Freeland, J. W.; Ke, X.; Ryan, P. J.; Kim, J. W.; Lee, J.-H.; Misra, R.; Schiffer, P.; Birol, T.; Fennie, C. J.; Schlom, D. G.

    2012-02-01

    Strain control of EuTiO3 has been shown under tensile strain the system converts to a multiferroic groundstate with ferromagnetic and ferroelectric order[1]. Here we present a study of the magnetic order in thin films of EuTiO3 grown on DyScO3(110) substrates by reactive molecular-beam epitaxy (MBE). Neutron scattering and magnetic measurements show the magnetic moment orders with an easy axis along only one of the (110) pseudocubic axis of the unit cell. Such an easy axis is connected to the uniaxial crystal structure that evolves from cubic to tetragonal with octahedral tilting, which agrees well with the strain dependent structure predicted under biaxial tensile strain. The magnetic anisotropy for Eu is attributed to an asymmetric crystal field due to the uniaxial symmetry of the Eu-O coordination. Work at Argonne, including the Advanced Photon, is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. [1] J.-H. Lee et al. Nature 466, 954 (2010).

  11. Emergence of magnetic order in ultra-thin pyrochlore iridate films

    Science.gov (United States)

    Cheema, Suraj; Serrao, Claudy; Mundy, Julia; Patankar, Shreyas; Birgeneau, Robert; Orenstein, Joseph; Salahuddin, Sayeef; Ramesh, Ramamoorthy

    We report on thickness-dependent magnetotransport in (111) - oriented Pb2Ir2O7-x (Pb227) epitaxial thin films. For thicknesses greater than 4 nm, the magnetoresistance (MR) of metallic Pb227 is positive, linear and non-saturated up to 14 T. Meanwhile at 4 nm, the conduction turns nonmetallic and the MR becomes negative and asymmetric upon field-cooling; such traits are reminiscent of all-in-all-out (AIAO) magnetic order in the insulating pyrochlore iridates. Hysteretic low-field MR dips and trained-untrained resistivity bifurcations suggest the presence of magnetic conducting domain walls within the chiral AIAO spin structure. Beyond just AIAO order, angular-dependent MR indicates a magnetic phase space hosting 2-in-2-out (2I2O) spin ice order. Such anomalous magnetotransport calls for re-evaluation of the pyrochlore iridate phase diagram, as epitaxially strained Pb227 exhibits traits reminiscent of both the insulating magnetic and metallic spin-liquid members. Furthermore, these results open avenues for realizing topological phase predictions in (111) - oriented pyrochlore slabs of kagome-triangular iridate heterostructures. This work is supported by the Office of Basic Energy Sciences of the US Department of Energy under Contract No. DE-AC02-05CH11231.

  12. Neutron Diffuse Reflectometry of Magnetic Thin Films with a 3He Analyzer

    Science.gov (United States)

    Chen, Wangchun; O'Donovan, Kevin; Borchers, Julie

    2005-03-01

    Polarized neutron reflectometry (PNR) is a powerful probe that characterizes the magnetization depth profile and magnetic domains in magnetic thin films. Although the conventionally used supermirrors are well-matched for specular PNR, they have limited angular acceptance and hence are impractical for complete characterization of the magnetic off-specular scattering where polarization analysis for diffusely reflected neutrons is required. Polarized ^3He gas, produced by optical pumping, can be used to polarize or analyze neutron beams because of the strong spin dependence of the neutron absorption cross section for ^3He. Here we report efficient polarization analysis of diffusely reflected neutrons in a reflectometry geometry using a polarized ^3He analyzer in conjunction with a position-sensitive detector (PSD). We obtained spin-resolved two-dimensional Qx-Qz reciprocal space maps for a patterned array of Co antidots in both the saturated and the demagnetized states. The preliminary results for a patterned amorphous bilayer, Gd40Fe60/ Tb55Fe45, measured with a ^3He analyzer and a PSD will also be discussed. Using the spin exchange optical pumping method we have achieved record high ^3He polarizations of 76% on the neutron beam line where we measured an initial analyzing efficiency of 0.97 and a neutron transmission for the desired spin state of 0.45.

  13. Electrode polarization and unusual magnetodielectric effect in a transformer oil-based magnetic nanofluid thin layer.

    Science.gov (United States)

    Rajnak, Michal; Dolnik, Bystrik; Kurimsky, Juraj; Cimbala, Roman; Kopcansky, Peter; Timko, Milan

    2017-01-07

    In the present paper, we provide low-frequency dielectric spectra for a thin layer of a nanofluid based on transformer oil and iron oxide nanoparticles stabilized by oleic acid. The complex dielectric permittivity measured in the frequency range from 1 mHz to 200 kHz shows an obvious electrode polarization effect and a Debye-like dielectric relaxation process. Both effects stem from the presence of space charge in the oil due to impurity ions, and in the nanofluid represented predominantly by a residual surfactant and uncompensated particle surface charge. It is shown that the spectra, which were measured in the temperature range from 298 K to 358 K, can be well represented by a fitting function consisted of one Havriliak-Negami term and the Jonscher's power law. In the investigated magnetic nanofluid layer, we found that the onset of the electrode polarization is suppressed to lower frequencies by the application of an external magnetic field (300 mT). This phenomenon is explained by a slowed-down migration of the space charge due to the Lorentz force and by a hindering effect of the formed magnetic nanoparticle aggregates. Surprisingly, a moderate decrease in the whole permittivity spectrum was observed for both parallel and perpendicular orientations of the electric and magnetic fields. This is in contradiction with the usual magnetodielectric anisotropy effect. Based on our qualitative analysis, we discuss potential reasons accountable for the observed effect.

  14. Structure and magnetic properties of highly textured nanocrystalline Mn–Zn ferrite thin film

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Jaison, E-mail: jaisonjosephp@gmail.com [Department of Physics, Goverment College, Khandola, Goa 403107 India (India); Tangsali, R.B. [Department of Physics, Goa University, Taleigao Plateau, Goa 403206 India (India); Pillai, V.P. Mahadevan [Department of Optoelectronics, University of Kerala,Thiruvananthapuram, Kerala 695581 India (India); Choudhary, R.J.; Phase, D.M.; Ganeshan, V. [UGC-DAE-CSR Indore, Madhya Pradesh 452017 India. (India)

    2015-01-01

    Nanoparticles of Mn{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} were chemically synthesized by co-precipitating the metal ions in aqueous solutions in a suitable alkaline medium. The identified XRD peaks confirm single phase spinal formation. The nanoparticle size authentication is carried out from XRD data using Debye Scherrer equation. Thin film fabricated from this nanomaterial by pulse laser deposition technique on quartz substrate was characterized using XRD and Raman spectroscopic techniques. XRD results revealed the formation of high degree of texture in the film. AFM analysis confirms nanogranular morphology and preferred directional growth. A high deposition pressure and the use of a laser plume confined to a small area for transportation of the target species created certain level of porosity in the deposited thin film. Magnetic property measurement of this highly textured nanocrystalline Mn–Zn ferrite thin film revealed enhancement in properties, which are explained on the basis of texture and surface features originated from film growth mechanism.

  15. Stress analysis, structure and magnetic properties of sputter deposited Ni-Mn-Ga ferromagnetic shape memory thin films

    Science.gov (United States)

    Annadurai, A.; Manivel Raja, M.; Prabahar, K.; Kumar, Atul; Kannan, M. D.; Jayakumar, S.

    2011-11-01

    The residual stress instituted in Ni-Mn-Ga thin films during deposition is a key parameter influencing their shape memory applications by affecting its structural and magnetic properties. A series of Ni-Mn-Ga thin films were prepared by dc magnetron sputtering on Si(1 0 0) and glass substrates at four different sputtering powers of 25, 45, 75 and 100 W for systematic investigation of the residual stress and its effect on structure and magnetic properties. The residual stresses in thin films were characterized by a laser scanning technique. The as-deposited films were annealed at 600 °C for 1 h in vacuum for structural and magnetic ordering. The compressive stresses observed in as-deposited films transformed into tensile stresses upon annealing. The annealed films were found to be crystalline and possess mixed phases of both austenite and martensite, exhibiting good soft magnetic properties. It was found that the increase of sputtering power induced coarsening in thin films. Typical saturation magnetization and coercivity values were found to be 330 emu/cm 3 and 215 Oe, respectively. The films deposited at 75 and 100 W display both structural and magnetic transitions above room temperature.

  16. Anomalous Hall effect sensors based on magnetic element doped topological insulator thin films

    Science.gov (United States)

    Ni, Yan; Zhang, Zhen; Nlebedim, Ikenna; Jiles, David

    Anomalous Hall effect (AHE) is recently discovered in magnetic element doped topological insulators (TIs), which promises low power consumption highly efficient spintronics and electronics. This discovery broaden the family of Hall effect (HE) sensors. In this work, both HE and AHE sensor based on Mn and Cr doped Bi2Te3 TI thin films will be systematically studied. The influence of Mn concentration on sensitivity of MnxBi2-xTe3 HE sensors will be discussed. The Hall sensitivity increase 8 times caused by quantum AHE will be reported. AHE senor based on Cr-doped Bi2Te3 TI thin films will also be studied and compared with Mn doped Bi2Te3 AHE sensor. The influence of thickness on sensitivity of CrxBi2-xTe3 AHE sensors will be discussed. Ultrahigh Hall sensitivity is obtained in Cr doped Bi2Te3. The largest Hall sensitivity can reach 2620 Ω/T in sensor which is almost twice higher than that of the normal semiconductor HE sensor. Our work indicates that magnetic element doped topological insulator with AHE are good candidates for ultra-sensitive Hall effect sensors.

  17. Microstructure and magnetic properties of sputtered Fe-Pt thin films

    CERN Document Server

    Mahalingam, T; Chen, J H; Wang, S F; Inoue, K

    2003-01-01

    The characterization of rf magnetron-sputtered Fe-Pt thin films at various compositions (Pt = 15, 24, 46 and 78 at%) is reported. X-ray diffraction studies on annealed Fe-46%Pt thin films at 600 deg C revealed an ordered L1 sub 0 gamma sub 2 -FePt phase with fct structure whereas annealed Fe-24%Pt and Fe-78%Pt films exhibited ordered gamma sub 1 -Fe sub 3 Pt and gamma sub 3 -FePt sub 3 phases, respectively. The effects of argon quenching and rapid thermal annealing (RTA) on the structural and magnetic properties are investigated. When the films are annealed at 600 deg C for 1 h and then quenched to room temperature in argon gas, ordered gamma sub 2 -FePt with L1 sub 0 phase is obtained. Argon-quenched and rapid thermal annealed films exhibit microtwins in scanning electron microscopy analysis. The appearance of microtwins may be attributed to the planar defects developed in the FePt films due to the release of elastic strain during annealing. The saturation magnetization is found to increase with ferrous cont...

  18. Structural and magnetic properties of pure and Cu doped In{sub 2}O{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, N. Sai; Kaleemulla, S., E-mail: skaleemulla@gmail.com; Rao, N. Madhusudhana; Krishnamoorthi, C.; Begam, M. Rigana [Thin Films Laboratory, School of Advanced Sciences, VIT University, Vellore – 632014 (India); Amarendra, G. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam –603102 (India); UGC-DAE-CSR, Kalpakkam Node, Kokilamedu-603104 (India)

    2015-06-24

    Pure and Cu (7 at.%) doped In{sub 2}O{sub 3} thin films were prepared using an electron beam evaporation technique. A systematic study was carried out on the structural, chemical and magnetic properties of the thin films. X-ray diffraction analysis revealed that all the films were cubic in structure. The pure and Cu doped In{sub 2}O{sub 3} thin films showed ferromagnetism at room temperature. The Cu doped In{sub 2}O{sub 3} thin films showed the saturation magnetization, coercivity and retentivity of 38.71 emu/cm{sup 3}, 245 G and 5.54 emu/cm{sup 3}, respectively.

  19. Nanomagnetic behavior of fullerene thin films in Earth magnetic field in dark and under polarization light influences.

    Science.gov (United States)

    Koruga, Djuro; Nikolić, Aleksandra; Mihajlović, Spomenko; Matija, Lidija

    2005-10-01

    In this paper magnetic fields intensity of C60 thin films of 60 nm and 100 nm thickness under the influence of polarization lights are presented. Two proton magnetometers were used for measurements. Significant change of magnetic field intensity in range from 2.5 nT to 12.3 nT is identified as a difference of dark and polarization lights of 60 nm and 100 nm thin films thickness, respectively. Specific power density of polarization light was 40 mW/cm2. Based on 200 measurement data average value of difference between magnetic intensity of C60 thin films, with 60 nm and 100 nm thickness, after influence of polarization light, were 3.9 nT and 9.9 nT respectively.

  20. Magnetic Properties and Nanostructures of FePtCu:C Thin Films with FePt Underlayers

    Institute of Scientific and Technical Information of China (English)

    JIN Ling-Fang; YAN Ming-Lang

    2007-01-01

    Magnetic properties and nanostructures of FePtCu:C thin films with FePt underlayers (ULs) are studied. The effect of FePt ULs on the orientation and magnetic properties of the thin films are investigated by adjusting FePt UL thicknesses from 2nm to 14nm. X-ray diffraction (XRD) scans reveal that the orientation of the films is dependent on FePt UL thickness. For a 5-nm FePtCu:C nanocomposite thin film with a 2-nm FePt UL, the coercivity is 6.5 KOe, the correlation length is 59nm, the desired face-centred-tetragonal (fct) ordered structure [L10 phase] is formed and the c axis normal to the film plane [(001) texture] is obtained. These results indicate that the better orientation and magnetic properties of the films can be tuned by decreasing the thickness of the FePt UL.

  1. Study of electronic structure and magnetic properties of epitaxial Co{sub 2}FeAl Heusler Alloy Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Soni, S. [Department of Pure & Applied Physics, University of Kota, Kota 324007 (India); Dalela, S., E-mail: sdphysics@rediffmail.com [Department of Pure & Applied Physics, University of Kota, Kota 324007 (India); Sharma, S.S. [Department of Physics, Govt. Women Engineering College, Ajmer (India); Liu, E.K.; Wang, W.H.; Wu, G.H. [State Key Laboratory for Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Kumar, M. [Department of Physics, Malviya National Institute of Technology, Jaipur-302017 (India); Garg, K.B. [Department of Physics, University of Rajasthan, Jaipur-302004 (India)

    2016-07-25

    This work reports the magnetic and electronic characterization of plane magnetized buried Heusler Co{sub 2}FeAl nano thin films of different thickness by X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements. . The spectra on both Fe- and Co L{sub 2,3} edges show a pronounced magnetic dichroic signal in remanence, corresponding to a ferromagnetically-aligned moments on Fe and Co atoms conditioning the peculiar characteristics of the Co{sub 2}FeAl Heusler compound (a half-metallic ferromagnet). The detailed knowledge of the related magnetic and electronic properties of these samples over a wide range of thickness of films are indispensable for achieving a higher tunnel magnetoresistance ratio, and thus for spintronics device applications. - Highlights: • Electronic structure and Magnetic Properties of Epitaxial Co{sub 2}FeAl Heusler Films. • X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). • Fe- and Co L{sub 2,3} edges show a pronounced magnetic dichroic signal in remanence. • Calculated Orbital, Spin and total magnetic moments of Fe and Co for 30 nm Co{sub 2}FeAl thin film. • The total magnetic moment of Fe at L{sub 2,3} edges increases with the thickness of the Co2FeAl films.

  2. Magnetic domain structure in nanocrystalline Ni-Zn-Co spinel ferrite thin films using off-axis electron holography

    Science.gov (United States)

    Zhang, D.; Ray, N. M.; Petuskey, W. T.; Smith, D. J.; McCartney, M. R.

    2014-08-01

    We report a study of the magnetic domain structure of nanocrystalline thin films of nickel-zinc ferrite. The ferrite films were synthesized using aqueous spin-spray coating at low temperature (˜90 °C) and showed high complex permeability in the GHz range. Electron microscopy and microanalysis revealed that the films consisted of columnar grains with uniform chemical composition. Off-axis electron holography combined with magnetic force microscopy indicated a multi-grain domain structure with in-plane magnetization. The correlation between the magnetic domain morphology and crystal structure is briefly discussed.

  3. Structural and magnetic properties of zinc ferrite thin films irradiated by 90 keV neon ions

    Energy Technology Data Exchange (ETDEWEB)

    Gafton, E.V., E-mail: elena.gafton@insp.jussieu.fr [Alexandru Ioan Cuza University, Faculty of Physics, 11 Carol I Blv., Iasi 700506 (Romania); Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Bulai, G., E-mail: georgiana.bulai@yahoo.com [Alexandru Ioan Cuza University, Faculty of Physics, 11 Carol I Blv., Iasi 700506 (Romania); Caltun, O.F., E-mail: caltun@uaic.ro [Alexandru Ioan Cuza University, Faculty of Physics, 11 Carol I Blv., Iasi 700506 (Romania); Cervera, S., E-mail: sophie.cervera@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Macé, S., E-mail: stephane.mace@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Trassinelli, M., E-mail: martino.trassinelli@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Steydli, S., E-mail: sebastien.steydli@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Vernhet, D., E-mail: dominique.vernhet@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France)

    2016-08-30

    Highlights: • Effect of different ion beam fluences on zinc ferrite thin films structure was investigated. • First reported results on zinc ferrite thin films irradiated with slow highly charged ions. • Increased magnetization was observed for samples irradiated even at low fluence. • Measurements of blocking temperature of thin films before and after irradiation. - Abstract: The effects of 90 keV neon beam irradiation on the structure and magnetic properties of zinc ferrite thin films have been investigated through several methods, namely, X-ray diffraction technique, Vibrating Sample and SQUID magnetometers. Beforehand, the pristine have also been characterized using profilometry and microscopy techniques. In particular single-phase formation of the thin films deposited on monocrystalline Si (111) substrate by pulsed laser deposition technique was confirmed. Crystal lattice, coercivity, saturation magnetization have been studied for the first time, as a function of ion penetration depth and irradiation fluence. The chemical composition and the crystallinity of the films are not affected with the ion impact acting as a mechanical stress relief. On the contrary, both magnetization and coercivity are sensitive to Ne{sup q+} ion irradiation and exhibit different behaviours depending on the ion fluence range.

  4. Technique for high axial shielding factor performance of large-scale, thin, open-ended, cylindrical Metglas magnetic shields

    CERN Document Server

    Malkowski, S; Hona, B; Mattie, C; Woods, D; Yan, H; Plaster, B; 10.1063/1.3605665

    2011-01-01

    Metglas 2705M is a low-cost commercially-available, high-permeability Cobalt-based magnetic alloy, provided as a 5.08-cm wide and 20.3-$\\mu$m thick ribbon foil. We present an optimized construction technique for single-shell, large-scale (human-size), thin, open-ended cylindrical Metglas magnetic shields. The measured DC axial and transverse magnetic shielding factors of our 0.61-m diameter and 1.83-m long shields in the Earth's magnetic field were 267 and 1500, for material thicknesses of only 122 $\\mu$m (i.e., 6 foil layers). The axial shielding performance of our single-shell Metglas magnetic shields, obtained without the use of magnetic shaking techniques, is comparable to the performance of significantly thicker, multiple-shell, open-ended Metglas magnetic shields in comparable-magnitude, low-frequency applied external fields reported previously in the literature.

  5. Magnetization reversal in ferromagnetic thin films induced by spin-orbit interaction with Slonczewski-like spin transfer torque

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jia, E-mail: lijia@wipm.ac.cn [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)

    2014-10-07

    We theoretically investigate the dynamics of magnetization in ferromagnetic thin films induced by spin-orbit interaction with Slonczewski-like spin transfer torque. We reproduce the experimental results of perpendicular magnetic anisotropy films by micromagnetic simulation. Due to the spin-orbit interaction, the magnetization can be switched by changing the direction of the current with the assistant of magnetic field. By increasing the current amplitude, wider range of switching events can be achieved. Time evolution of magnetization has provided us a clear view of the process, and explained the role of minimum external field. Slonczewski-like spin transfer torque modifies the magnetization when current is present. The magnitude of the minimum external field is determined by the strength of the Slonczewski-like spin transfer torque. The investigations may provide potential applications in magnetic memories.

  6. CVD synthesis of polycrystalline magnetite thin films: structural, magnetic and magnetotransport properties

    Energy Technology Data Exchange (ETDEWEB)

    Mantovan, R; Lamperti, A; Georgieva, M; Tallarida, G; Fanciulli, M, E-mail: roberto.mantovan@mdm.infm.i [Laboratorio Nazionale MDM CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (Italy)

    2010-02-17

    Magnetite (Fe{sub 3}O{sub 4}) is predicted to be half metallic at room temperature (RT) and it shows the highest Curie temperature among oxides. The use of Fe{sub 3}O{sub 4} thin films is therefore promising for spintronic devices such as magnetic tunnel junctions (MTJs) and magnetoresistive sensors. The structural, magnetic and magnetotransport properties of magnetite are reported to be strongly dependent on the growth conditions. We have developed a very simple deposition chamber for growing thin magnetite films via a chemical vapour deposition (CVD) process based on the Fe{sub 3}(CO){sub 12} carbonyl precursor. The structural, morphological, and magnetic properties of the as deposited Fe{sub 3}O{sub 4} films have been investigated by means of time of flight secondary ion mass spectrometry, grazing incidence x-ray diffraction, x-ray reflectivity, atomic force microscopy, conversion electron Moessbauer spectroscopy and superconducting quantum interference device magnetometry. Magnetotransport measurements show magnetoresistance up to -2.4% at RT at the maximum applied field of 1.1 T. Resistivity measurements in the 100-300 K temperature range reveal that the magnetotransport properties of the Fe{sub 3}O{sub 4} films are governed by inter-granular tunnelling of the spin-polarized electrons. The spin polarization is estimated to be around -16%. A possible route for increasing the spin-polarized performances of our magnetite films is proposed. We have also deposited Fe{sub 3}O{sub 4}/MgO/Co stacks by using a combined CVD and atomic layer-deposition process. The trilayer's hysteresis curve evidences the presence of two distinct switching fields making it promising for magnetite-based MTJ applications.

  7. CVD synthesis of polycrystalline magnetite thin films: structural, magnetic and magnetotransport properties

    Science.gov (United States)

    Mantovan, R.; Lamperti, A.; Georgieva, M.; Tallarida, G.; Fanciulli, M.

    2010-02-01

    Magnetite (Fe3O4) is predicted to be half metallic at room temperature (RT) and it shows the highest Curie temperature among oxides. The use of Fe3O4 thin films is therefore promising for spintronic devices such as magnetic tunnel junctions (MTJs) and magnetoresistive sensors. The structural, magnetic and magnetotransport properties of magnetite are reported to be strongly dependent on the growth conditions. We have developed a very simple deposition chamber for growing thin magnetite films via a chemical vapour deposition (CVD) process based on the Fe3(CO)12 carbonyl precursor. The structural, morphological, and magnetic properties of the as deposited Fe3O4 films have been investigated by means of time of flight secondary ion mass spectrometry, grazing incidence x-ray diffraction, x-ray reflectivity, atomic force microscopy, conversion electron Mössbauer spectroscopy and superconducting quantum interference device magnetometry. Magnetotransport measurements show magnetoresistance up to -2.4% at RT at the maximum applied field of 1.1 T. Resistivity measurements in the 100-300 K temperature range reveal that the magnetotransport properties of the Fe3O4 films are governed by inter-granular tunnelling of the spin-polarized electrons. The spin polarization is estimated to be around -16%. A possible route for increasing the spin-polarized performances of our magnetite films is proposed. We have also deposited Fe3O4/MgO/Co stacks by using a combined CVD and atomic layer-deposition process. The trilayer's hysteresis curve evidences the presence of two distinct switching fields making it promising for magnetite-based MTJ applications.

  8. Experimental studies in magnetically induced transverse force-frequency effect in thin quartz microresonators

    Energy Technology Data Exchange (ETDEWEB)

    Hatipoglu, Gokhan [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Tadigadapa, Srinivas, E-mail: sat10@psu.edu [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-07-21

    In this work, the transverse force-frequency sensitivity of magnetostrictive Metglas{sup ®} (Fe{sub 85}B{sub 5}Si{sub 10}) thin film coated AT-cut thickness shear mode quartz thin plate microresonator (500 μm × 500 μm × 19 μm) is experimentally measured and modeled in Lagrangian formulation by coupling magnetostrictive deformation equations with the basic plate equations from the theory of small deformation. The quartz plate resonator is fabricated by micromachining techniques and released into fixed-free structure using focused ion beam milling. Application of a magnetic field results in the out-of-plane bending of the structure due to elastic coupling between the magnetostrictive Metglas{sup ®} and quartz resonator layers. As a result of the transverse loading and out-of-plane bending, the admittance characteristics of the resonator shifts, and these shifts are recorded in real time utilizing a network analyzer. The sensitivity is experimentally measured to be 162.3 mdeg/Oe for phase, corresponding to a frequency sensitivity of Δf/H = 11 Hz/Oe. The equivalent force-frequency sensitivity can then be calculated as 2.36 μN/Hz using the developed model. The coupled domain analysis fits well with the experimental data. Further reduction of quartz thickness and optimization of the thickness ratio of the magnetostrictive to quartz layers offers the possibility of exploiting the stress sensitivity of plate microresonators as sensitive magnetic field sensors capable of low nanoTesla to picoTesla level magnetic flux densities.

  9. Moving magnetic tubes: fragmentation, vortex streets and the limit of the approximation of thin flux tubes

    Science.gov (United States)

    Cheung, M. C. M.; Moreno-Insertis, F.; Schüssler, M.

    2006-05-01

    Aims.We study the buoyant rise of magnetic flux tubes in a stratified layer over a range of Reynolds numbers (25 ⪉ Re ⪉ 2600) by means of numerical simulations. Special emphasis is placed on studying the fragmentation of the rising tube, its trailing wake and the formation of a vortex street in the high-Reynolds number regime. Furthermore, we evaluate the relevance of the thin flux tube approximation with regard to describing the evolution of magnetic flux tubes in the simulations. Methods: .We used the FLASH code, which has an adaptive mesh refinement (AMR) algorithm, thus allowing the simulations to be carried out at high Reynolds numbers. Results: .The evolution of the magnetic flux tube and its wake depends on the Reynolds number. At Re up to a few hundred, the wake consists of two counter-rotating vortex rolls. At higher Re, the vortex rolls break up and the shedding of flux into the wake occurs in a more intermittent fashion. The amount of flux retained by the central portion of the tube increases with the field line twist (in agreement with previous literature) and with Re. The time evolution of the twist is compatible with a homologous expansion of the tube. The motion of the central portion of the tube in the simulations is very well described by the thin flux tube model whenever the effects of flux loss or vortex forces can be neglected. If the flux tube has an initial net vorticity, it undergoes asymmetric vortex shedding. In this case, the lift force accelerates the tube in such a way that an oscillatory horizontal motion is super-imposed on the vertical rise of the tube, which leaves behind a vortex street. This last result is in accordance with previous simulations reported in the literature, which were carried out at lower Reynolds number.

  10. Ultrafast Magnetization Dynamics of SrRuO3 Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Langner, Matthew C. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2009-05-19

    Itinerant ferromagnet SrRuO3 has drawn interest from physicists due to its unusual transport and magnetic properties as well as from engineers due to its low resistivity and good lattice-matching to other oxide materials. The exact electronic structure remains a mystery, as well as details of the interactions between magnetic and electron transport properties. This thesis describes the use of time-resolved magneto-optical Kerr spectroscopy to study the ferromagnetic resonance of SrRuO3 thin films, where the ferromagnetic resonance is initiated by a sudden change in the easy axis direction in response to a pump pulse. The rotation of the easy axis is induced by laser heating, taking advantage of a temperature-dependent easy axis direction in SrRuO3 thin films. By measuring the change in temperature of the magnetic system in response to the laser pulse, we find that the specific heat is dominated by magnons up to unusually high temperature, ~100 K, and thermal diffusion is limited by a boundary resistance between the film and the substrate that is not consistent with standard phonon reflection and scattering models. We observe a high FMR frequency, 250 GHz, and large Gilbert damping parameter, α ≈1, consistent with strong spin-orbit coupling. We observe a time-dependent change in the easy axis direction on a ps time-scale, and we find that parameters associated with the change in easy axis, as well as the damping parameter, have a non-monotonic temperature dependence similar to that observed in anomalous Hall measurements.

  11. Thermal annealing and magnetic anisotropy of NiFe thin films on n{sup +}-Si for spintronic device applications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Q.H. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Gansu Key Laboratory of Sensor and Sensor Technology, Institute of Sensor Technology, Gansu Academy of Science, Lanzhou 730000 (China); Huang, R. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Wang, L.S. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Wu, Z.G., E-mail: zgwu@lzu.edu.cn [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, C., E-mail: lich@xmu.edu.cn [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Luo, Q. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Zuo, S.Y. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, J. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Peng, D.L. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Han, G.L. [Gansu Key Laboratory of Sensor and Sensor Technology, Institute of Sensor Technology, Gansu Academy of Science, Lanzhou 730000 (China); Yan, P.X. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2015-11-15

    To ensure that the magnetic metal electrodes can meet the requirements of the spin injection, NiFe films prepared both on HfO{sub 2} dielectric layer and n{sup +}-Si directly by sputtering deposition, and treated by conventional furnace annealing and/or high vacuum magnetic field annealing were investigated. It was found that thermal annealing at 250 °C improved the crystalline quality and reduced surface roughness of the NiFe films, thus enhancing its saturation magnetization intensity. The 100 nm thick NiFe films had too large coercive force and saturation magnetization intensity in vertical direction to meet the requirements of Hanle curve detection. While, 30 nm thick NiFe films showed paramagnetic hysteresis loops in vertical direction, and the magnetization intensity of the sample after annealing at 250 °C for 30 min was less than 2% to the parallel when the external magnetic field was given between ±10 Oe. This was preferred to Hanle curve detection. The thin HfO{sub 2} dielectric layer between metal and Si partially suppressed the diffusion of Ni in NiFe into Si substrate and formation of NiSi, greatly enhancing the saturation magnetization intensity of the Al/NiFe/HfO{sub 2}/Si sample by thermal annealing. Those results suggest that Al/NiFe/HfO{sub 2}/Si structure, from the point view of magnetic electrodes, would be suitable for spin injection and detection applications. - Highlights: • The saturation magnetization intensity of NiFe thin-film was enhanced by thermal annealing. • A paramagnetic hysteresis loop of NiFe thin-film was observed in vertical direction. • The thin HfO{sub 2} dielectric layer between NiFe and Si partially suppressed the diffusion of Ni into Si.

  12. Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films

    KAUST Repository

    Lu, Chengliang

    2013-12-02

    The mutual controls of ferroelectricity and magnetism are stepping towards practical applications proposed for quite a few promising devices in which multiferroic thin films are involved. Although ferroelectricity stemming from specific spiral spin ordering has been reported in highly distorted bulk perovskite manganites, the existence of magnetically induced ferroelectricity in the corresponding thin films remains an unresolved issue, which unfortunately halts this step. In this work, we report magnetically induced electric polarization and its remarkable response to magnetic field (an enhancement of ?800% upon a field of 2 Tesla at 2 K) in DyMnO3 thin films grown on Nb-SrTiO3 substrates. Accompanying with the large polarization enhancement, the ferroelectric coercivity corresponding to the magnetic chirality switching field is significantly increased. A picture based on coupled multicomponent magnetic structures is proposed to understand these features. Moreover, different magnetic anisotropy related to strain-suppressed GdFeO 3-type distortion and Jahn-Teller effect is identified in the films.

  13. Electrodynamics in a Very Thin Current Sheet Leading to Magnetic Reconnection

    Science.gov (United States)

    Singh, Nagendra; Deverapalli, Chakri; Khazanov, George

    2006-01-01

    We study the formation of a very thin current sheet (CS) and associated plasma electrodynamics using three-dimensional (3-D) particle-in-cell simulations with ion to electron mass ratio M/m=1836. The CS is driven by imposed anti-parallel magnetic fields. The noteworthy features of the temporal evolution of the CS are the following: (i) Steepening of the magnetic field profile B,(z) in the central part of the CS, (ii) Generation of three-peak current distribution with the largest peak in the CS center as B,(z) steepens, (iii) Generation of converging electric fields forming a potential well in the CS center in which ions are accelerated. (iv) Electron and ion heating in the central part of the CS by current-driven instabilities (CDI). (v) Re-broadening of the CS due to increased kinetic plasma pressure in the CS center. (vi) Generation of electron temperature anisotropy with temperature perpendicular to the magnetic field being larger than the parallel one. (vii) Current disruption by electron trapping in an explosively growing electrostatic instability (EGEI) and electron tearing instability (ETI). (viii)The onset of EGEI coincides with an increase in the electron temperature above the temperature of the initially hot ions as well as the appearance of new shear in the electron drift velocity. (ix) Bifurcation of the central CS by the current disruption. (x) Magnetic reconnection (MR) beginning near the null in B, and spreading outward. (xi) Generation of highly energized electrons reaching relativistic speeds and having isotropic pitch-angle distribution in the region of reconnected magnetic fields. We compare some of these features of the current sheet with results from laboratory and space experiments.

  14. Electrodynamics in a very thin current sheet leading to magnetic reconnection

    Directory of Open Access Journals (Sweden)

    N. Singh

    2006-01-01

    Full Text Available We study the formation of a very thin current sheet (CS and associated plasma electrodynamics using three-dimensional (3-D particle-in-cell simulations with ion to electron mass ratio M/m=1836. The CS is driven by imposed anti-parallel magnetic fields. The noteworthy features of the temporal evolution of the CS are the following: (i Steepening of the magnetic field profile Bx(z in the central part of the CS, (ii Generation of three-peak current distribution with the largest peak in the CS center as Bx(z steepens, (iii Generation of converging electric fields forming a potential well in the CS center in which ions are accelerated. (iv Electron and ion heating in the central part of the CS by current-driven instabilities (CDI. (v Re-broadening of the CS due to increased kinetic plasma pressure in the CS center. (vi Generation of electron temperature anisotropy with temperature perpendicular to the magnetic field being larger than the parallel one. (vii Current disruption by electron trapping in an explosively growing electrostatic instability (EGEI and electron tearing instability (ETI. (viiiThe onset of EGEI coincides with an increase in the electron temperature above the temperature of the initially hot ions as well as the appearance of new shear in the electron drift velocity. (ix Bifurcation of the central CS by the current disruption. (x Magnetic reconnection (MR beginning near the null in Bx and spreading outward. (xi Generation of highly energized electrons reaching relativistic speeds and having isotropic pitch-angle distribution in the region of reconnected magnetic fields. We compare some of these features of the current sheet with results from laboratory and space experiments.

  15. Magnetic and structural properties of thin films and nanoparticles studied by scattering methods

    Energy Technology Data Exchange (ETDEWEB)

    Feygenson, M.

    2007-12-20

    The present work concerns the magnetic and structural properties of magnetic thin films and magnetic nanoparticles studied by scattering methods. The structural properties of epitaxially grown Fe/Cr/Fe trilayer were studied with anomalous x-ray scattering. Two different X-ray energies have been used; (i) one E{sub 1}=5985 eV to match the maximum contrast of the Fe/Cr interface close to the Cr absorption K-edge and (ii) a second one E{sub 2}=6940 eV where the Fe/Cr interface displays the lowest contrast. The specular reflectivity and longitudinal diffuse scans together with omega scans for both energies were measured. The simulations within the frame of Distorted Wave Born Approximation (DWBA) allowed us to describe quantitatively the morphology of each interface. The roughness, Hurst parameter and the thickness of every layer as well as an oxidation effect at the surface of the sample are derived. The influence of confinement on the magnetic behavior, was investigated in MnO embedded in a porous glass. We studied the magnetic order and phase transition of MnO nanoparticles by polarized neutron scattering. From the temperature dependence of the magnetic ((1)/(2) (1)/(2) (1)/(2)) Bragg intensity we obtained that for the MnO nanoparticles the phase transition is continuous with a Neel temperature T{sub N}=122 K. Furthermore, we observed that a part of the MnO nanoparticle material remains disordered even at 10 K. In order to study the spin-canting effect in magnetic nanoparticles, we explored a synthesis route of Co nanoparticles in which we employed water-in-oil microemulsions that are stabilized by the nonionic surfactants of the ethoxylated alkyl- or arylether series such as C{sub 12}E{sub 5} and Igepal CO520 and contain the NaBH{sub 4}-solution. Co nanoparticle formation is then induced by injecting a solution of Co(AOT){sub 2} in hexane. For a structural characterization of the Co nanoparticles, we performed small-angle X-ray scattering experiments at the JUSIFA

  16. Enhancement of magnetic domain topologies in Co/Pt thin films by fine tuning the magnetic field path throughout the hysteresis loop

    Energy Technology Data Exchange (ETDEWEB)

    Westover, Andrew S. [Physics Department, Brigham Young University, Provo, UT 84602 (United States); Chesnel, Karine, E-mail: kchesnel@byu.edu [Physics Department, Brigham Young University, Provo, UT 84602 (United States); Hatch, Kelsey; Salter, Philip [Physics Department, Brigham Young University, Provo, UT 84602 (United States); Hellwig, Olav [HGST a Western Digital Company, San Jose, CA 95135 (United States)

    2016-02-01

    We have studied the influence of magnetic history on the topology of perpendicular magnetic domains in a thin ferromagnetic film made of [Co(8 Å)/Pt(7 Å)]{sub 50} multilayers. More specifically, we have followed the morphological changes in the domain pattern when applying a magnetic field perpendicular to the layer, throughout minor and major magnetization loops, and in the resulting remanent state. We carried out this study by using MFM microscopy with an in-situ magnetic field. We find that the morphology of the magnetic domain pattern is greatly influenced by the magnetic history of the material and that some features, such as the degree of bubbliness (i.e., the extent of bubble domain formation) and density of isolated domains can be enhanced by fine tuning the magnetic field path within the major hysteresis loop towards different remanent states. In particular, we see how hysteresis is correlated to irreversible changes in the domain morphology. More interestingly, we find that the magnetic domain morphology at remanence can be changed from an interconnected labyrinthine stripe state to a state of many separated bubble domains by fine tuning the magnitude of the field previously applied to the material. These results agree well with other findings, such as the magnetic reversal behavior and magnetic memory effects in Co/Pt multilayers, and provide opportunities for potential technological applications. - Highlights: • Morphology of magnetic domains in Co/Pt thin films changes with magnetic history. • Domain morphology evolves from a maze to a bubble pattern when field approaches H{sub p}. • Domain morphology at remanence depends on magnitude H{sub m} of previously applied field. • A topological maze-to-bubble phase transition occurs at remanence when H{sub m} is near H{sup ⁎}. • Density of oppositely aligned domains peaks up when H{sub m} is near H{sup ⁎}.

  17. Soft X-Ray Magnetic Imaging of Focused Ion Beam Lithographically Patterned Fe Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Paul J.; Shen, Tichan H.; Grundy, PhilJ.; Im, Mi Young; Fischer, Peter; Morton, Simon A.; Kilcoyne, Arthur D.L.

    2008-11-09

    We illustrate the potential of modifying the magnetic behavior and structural properties of ferromagnetic thin films using focused ion beam 'direct-write' lithography. Patterns inspired by the split-ring resonators often used as components in meta-materials were defined upon 15 nm Fe films using a 30 keV Ga{sup +} focused ion beam at a dose of 2 x 10{sup 16} ions cm{sup -2}. Structural, chemical and magnetic changes to the Fe were studied using transmission soft X-ray microscopy at the ALS, Berkeley CA. X-ray absorption spectra showed a 23% reduction in the thickness of the film in the Ga irradiated areas, but no change to the chemical environment of Fe was evident. X-ray images of the magnetic reversal process show domain wall pinning around the implanted areas, resulting in an overall increase in the coercivity of the film. Transmission electron microscopy showed significant grain growth in the implanted regions.

  18. Magnetic and magnetoelastic properties of epitaxial SmFe{sub 2} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Fuente, C de la; Arnaudas, J I; Ciria, M; Del Moral, A [Departamento de Magnetismo de Solidos and Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de los Materiales de Aragon and Universidad de Zaragoza, 50071, Zaragoza (Spain); Dufour, C; Dumesnil, K, E-mail: cesar@unizar.e [Laboratoire de Metallurgie Physique et de Science des Materiaux, Universite Henry Poincare, Nancy 1, BP 239, 54506 (France)

    2010-02-03

    We report on magnetic and magnetoelastic measurements for a 5000 A (110) SmFe{sub 2} thin film, which was successfully analyzed by means of a point charge model for describing the effect of the epitaxial growth in this kind of system. Some of the main conclusions of the Moessbauer and magnetoelastic results and the new magnetization results up to 5 T allow us to get a full description of the crystal electric field, exchange, and magnetoelastic behavior in this compound. So, new single-ion parameters are obtained for the crystal field interaction of samarium ions, A{sub 4}(r{sup 4}) = +755 K/ion and A{sub 6}(r{sup 6}) = -180 K/ion, and new single-ion magnetoelastic coupling B{sup gamma}{sup ,2}approx =-200 MPa and B{sup epsilon}{sup ,2}approx =800 MPa, which represent the tetragonal and the in-plane shear deformations, respectively. Moreover, the new thermal behavior of the samarium magnetic moment, the exchange coupling parameter, and the magnetocrystalline anisotropy of the iron sublattice are obtained too. From these, the softening of the spin reorientation transition with respect to the bulk case could be accounted for.

  19. Microstructures and magnetic properties of [SiO2/FePt]5/Ag thin films

    Institute of Scientific and Technical Information of China (English)

    FAN Jiu-ping; XU Xiao-hong; JIANG Feng-xian; TIAN Bao-qiang; WU Hai-shun

    2008-01-01

    [SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO2/FePt]5/Ag films are changed into L10 and (111) mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controllingSiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 (0. 6nm)/FePt (3 nm)]5/Ag (50 nm) films and highly (001)-oriented films can be obtained in the [SiO2 (2 nm)/FePt (3 nm)]5/Ag (50 nm) films.

  20. Morphology and Magnetism of Atomically Thin Layers of Chromia -- An STM Investigation

    Science.gov (United States)

    Chen, Xumin; Kenkel, Donna; Rojas, Geoffrey; He, Xi; Binek, Christian; Enders, Axel

    2012-02-01

    A low temperature scanning tunneling microscopy (LT-STM) study of ultrathin chromium oxide films on Cu(111) is presented. The (0001) surface of Cr2O3 (chromia) exhibits long-range antiferromagnetic ordering, and its usefulness for electric field control of exchange bias has been recently established [Xi He, Ch. Binek, et al., Natuer Materials 9, 579 -- 585 (2010)]. We deposited ultrathin chromium layers on Cu(111), followed by post-annealing in oxygen partial pressures to promote oxidation of the chromium films. We find that chromium grows on Cu(111) in the Volmer-Weber mode, resulting in small 3D islands. During annealing, the small islands coalesce to form large, flat terraces and the most stable oxide of chromium, Cr2O3, is formed at 630 C. Spin-polarized scanning tunneling microscopy has been performed to image the layer-wise antiferromagnetism in different structural layers of the chromia films. Thin layers of cobalt have been deposited on the chromia so that the magnetism of the Co couples to that of the chromia. Imaging the magnetism of the Co islands on the Cr2O3 terraces with spin-polarized STM helped us distinguishing between magnetic and electronic contrast in the complex dI/dV maps of the chromia surface.

  1. Magnetic field dependence of the superconducting proximity effect in a two atomic layer thin metallic film

    Energy Technology Data Exchange (ETDEWEB)

    Caminale, Michael; Leon Vanegas, Augusto A.; Stepniak, Agnieszka; Oka, Hirofumi; Fischer, Jeison A.; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany)

    2015-07-01

    The intriguing possibility to induce superconductivity in a metal, in direct contact with a superconductor, is under renewed interest for applications and for fundamental aspects. The underlying phenomenon is commonly known as proximity effect. In this work we exploit the high spatial resolution of scanning tunneling spectroscopy at sub-K temperatures and in magnetic fields. We probe the differential conductance along a line from a superconducting 9 ML high Pb nanoisland into the surrounding two layer thin Pb/Ag wetting layer on a Si(111) substrate. A gap in the differential conductance indicates superconductivity of the Pb island. We observe an induced gap in the wetting layer, which decays with increasing distance from the Pb island. This proximity length is 21 nm at 0.38 K and 0 T. We find a non-trivial dependence of the proximity length on magnetic field. Surprisingly, we find that the magnetic field does not affect the induced superconductivity up to 0.3 T. However, larger fields of 0.6 T suppress superconductivity in the wetting layer, where the Pb island still remains superconducting. We discuss the unexpected robustness of induced superconductivity in view of the high electronic diffusivity in the metallic wetting layer.

  2. Goos-Hänchen effect and bending of spin wave beams in thin magnetic films

    Science.gov (United States)

    Gruszecki, P.; Romero-Vivas, J.; Dadoenkova, Yu. S.; Dadoenkova, N. N.; Lyubchanskii, I. L.; Krawczyk, M.

    2014-12-01

    For magnon spintronic applications, the detailed knowledge of spin wave (SW) beam dispersion, transmission (reflection) of SWs passing through (reflected from) interfaces, or borders or the scattering of SWs by inhomogeneities is crucial. These wave properties are decisive factors on the usefulness of a particular device. Here, we demonstrate, using micromagnetic simulations supported by an analytical model, that the Goos-Hänchen (GH) shift exists for SW reflecting from thin film edge and that with the effect becomes observable. We show that this effect will exist for a broad range of frequencies in the dipole-exchange range, with the magnetization degree of pinning at the film edge as the crucial parameter, whatever its nature. Moreover, we have also found that the GH effect can be accompanied or even dominating by a bending of the SW beam due to the inhomogeneity of the internal magnetic field. This inhomogeneity, created by demagnetizing field taking place at the film edge, causes gradual change of SWs refractive index. The refraction of the SW beams by the non-uniformity of the magnetic field enables the exploration of graded index magnonics and metamaterial properties for the transmission and processing of information at nanoscale.

  3. Goos-Hänchen effect and bending of spin wave beams in thin magnetic films

    Energy Technology Data Exchange (ETDEWEB)

    Gruszecki, P., E-mail: pawel.gruszecki@amu.edu.pl; Krawczyk, M., E-mail: krawczyk@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, Poznań 61-614 (Poland); Romero-Vivas, J. [Department of Electronic and Computer Engineering, University of Limerick, Limerick (Ireland); Dadoenkova, Yu. S.; Dadoenkova, N. N. [Donetsk Physical and Technical Institute of the National Academy of Sciences of Ukraine, 83114 Donetsk (Ukraine); Ulyanovsk State University, 42 Leo Tolstoy str., 432000 Ulyanovsk (Russian Federation); Lyubchanskii, I. L. [Donetsk Physical and Technical Institute of the National Academy of Sciences of Ukraine, 83114 Donetsk (Ukraine)

    2014-12-15

    For magnon spintronic applications, the detailed knowledge of spin wave (SW) beam dispersion, transmission (reflection) of SWs passing through (reflected from) interfaces, or borders or the scattering of SWs by inhomogeneities is crucial. These wave properties are decisive factors on the usefulness of a particular device. Here, we demonstrate, using micromagnetic simulations supported by an analytical model, that the Goos-Hänchen (GH) shift exists for SW reflecting from thin film edge and that with the effect becomes observable. We show that this effect will exist for a broad range of frequencies in the dipole-exchange range, with the magnetization degree of pinning at the film edge as the crucial parameter, whatever its nature. Moreover, we have also found that the GH effect can be accompanied or even dominating by a bending of the SW beam due to the inhomogeneity of the internal magnetic field. This inhomogeneity, created by demagnetizing field taking place at the film edge, causes gradual change of SWs refractive index. The refraction of the SW beams by the non-uniformity of the magnetic field enables the exploration of graded index magnonics and metamaterial properties for the transmission and processing of information at nanoscale.

  4. Ferromagnetic MnGaN thin films with perpendicular magnetic anisotropy for spintronics applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hwachol; Sukegawa, Hiroaki, E-mail: sukegawa.hiroaki@nims.go.jp; Ohkubo, Tadakatsu; Kasai, Shinya [National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Liu, Jun; Mitani, Seiji; Hono, Kazuhiro [National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8577 (Japan)

    2015-07-20

    Perpendicularly magnetized flat thin films of antiperovskite Mn{sub 67}Ga{sub 24}N{sub 9} were grown on an MgO(001) substrate by reactive sputtering using an argon/1% nitrogen gas mixture and a Mn{sub 70}Ga{sub 30} target. The films showed a saturation magnetization of 80 –100 kA/m, an effective perpendicular magnetic anisotropy (PMA) energy of 0.1–0.2 MJ/m{sup 3}, and a Curie temperature of 660–740 K. Upon increasing the N composition, the films transformed from ferromagnetic to antiferromagnetic as expected in the stoichiometric Mn{sub 3}GaN phase. Point contact Andreev reflection spectroscopy revealed that the ferromagnetic MnGaN has a current spin polarization of 57%, which is comparable to D0{sub 22}-MnGa. These findings suggest that MnGaN is a promising PMA layer for future spintronics devices.

  5. Induced magnetism in exfoliated graphene via proximity effect with yttrium iron garnet thin films

    Science.gov (United States)

    Amado, Mario; Li, Yang; di Bernardo, Angelo; Lombardo, Antonio; Ferrari, Andrea C.; Robinson, Jason

    The recent discovery of the quantum anomalous Hall effect (QAHE) in magnetically doped topological insulators cooled below in the milikelvin regime represents breakthrough in the field of spintronics. Theoretically, the QAHE should occur in graphene proximity coupled to a ferromagnetic insulato but with the promise of much higher operating temperatures for practical applications. Hints of proximity-induced magnetism in graphene coupled to yttrium iron garnet (YIG) films have been reported although the QAHE remains unobserved; the lack of a fully developed plateau in graphene/YIG devices can be attributed to poor interfacial coupling and therefore a dramatically reduced magnetic proximity effect. Here we report the deposition and characterisation of epitaxial thin-films of YIG on lattice-matched gadolinium gallium garnet substrates by pulsed laser deposition. Pristine exfoliated graphene flakes transferred mechanically onto the YIG are reported alongside results that correlate the effects of YIG morphology on the electronic and crystal properties of graphene by electrical (low temperature magnetoresistance measurements in Hall-bar-like configuration) and optical (Raman) means.

  6. Spin Waves in Magnetic Thin Films: New Types of Solitons and Electrical Control

    Science.gov (United States)

    Wang, Zihui

    New types of spin-wave solitons in magnetic thin films and the methods to control spin waves electrically are studied in this thesis. In the first part, the first observation of chaotic spin-wave solitons in yttrium iron garnet (YIG) thin film-based active feedback rings is presented. At some ring gain levels, one observes the self-generation of a single spin-wave soliton pulse in the ring. When the pulse circulates in the ring, its amplitude varies chaotically with time. The excitation of dark spin-wave envelope solitons in YIG thin film strips is also described. The formation of a pair of black solitons with a phase jump of 180° is observed for the first time. The excitation of bright solitons in the case of repulsive nonlinearity is also observed and is reproduced by a numerical simulation based on a high-order nonlinear Schrodinger equation. In the second part, the control of magnetization relaxation in ferromagnetic insulators via interfacial spin scattering is presented. In the experiments nanometer-thick YIG/Pt bi-layered structures are used, with the Pt layer biased by an electric voltage. The bias voltage produces a spin current across the Pt layer thickness due to the spin Hall effect. As this current scatters off the YIG surface, it exerts a torque on the YIG surface spins. This torque can reduce or increase the damping and thereby compress or broaden the ferromagnetic resonance linewidth of the YIG film, depending on the field/current configuration. The control of spin waves in a YIG thin film via interfacial spin scattering is also presented. In the experiments a 4.6-microm-thick YIG film strip with a 20-nm-thick Pt capping layer is used. A DC current pulse is applied to the Pt layer and produced a spin current across the Pt layer. As the spin current scatters off the YIG surface, it can either amplify or attenuate spin-wave pulses that travel in the YIG strip, depending on the current/field configuration.

  7. Heat-assisted magnetic probe recording onto a thin film with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Onoue, T; Siekman, M; Abelmann, L; Lodder, J C [Systems and Materials for Information storage (SMI), MESA Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede (Netherlands)

    2008-08-07

    The possibility of magnetic probe recording into a continuous perpendicular medium is discussed. By applying a current from the tip to the medium, a very localized area can be heated and bits as small as 80 nm in diameter could be written. This value is close to the calculated minimum diameter of reversed cylindrical domains in our perpendicular medium. A current can be injected directly from the tip to the medium by means of a current source, or one can use capacitive currents. We prefer the first method, since the current, and therefore the heating process, can be controlled more precisely. The energy required to write a bit is in the order of 1 nJ. Calculations show that most of the heat is dissipated at the tip end. Demagnetizing fields of the surrounding material play an important role and are so strong that bits can be written without applying an external field. By decreasing the film thickness, the demagnetizing fields are reduced, and selective overwriting of previously written bits could be demonstrated.

  8. Large anisotropic Fe orbital moments in perpendicularly magnetized Co2FeAl Heusler alloy thin films revealed by angular-dependent x-ray magnetic circular dichroism

    Science.gov (United States)

    Okabayashi, Jun; Sukegawa, Hiroaki; Wen, Zhenchao; Inomata, Koichiro; Mitani, Seiji

    2013-09-01

    Perpendicular magnetic anisotropy (PMA) in Heusler alloy Co2FeAl thin films sharing an interface with a MgO layer is investigated by angular-dependent x-ray magnetic circular dichroism. Orbital and spin magnetic moments are deduced separately for Fe and Co 3d electrons. In addition, the PMA energies are estimated using the orbital magnetic moments parallel and perpendicular to the film surfaces. We found that PMA in Co2FeAl is determined mainly by the contribution of Fe atoms with large orbital magnetic moments, which are enhanced at the interface between Co2FeAl and MgO. Furthermore, element specific magnetization curves of Fe and Co are found to be similar, suggesting the existence of ferromagnetic coupling between Fe and Co PMA directions.

  9. Magnetic Field Gradiometer with Sub-Micron Spatial Resolution Based on Caesium Vapour in an Extremely Thin Cell

    Directory of Open Access Journals (Sweden)

    Auzinsh M.

    2015-06-01

    Full Text Available In this paper we present a device for measuring the magnetic field and its gradient with a spatial resolution of several hundred nanometres. This device is based on caesium metal vapour confined to an extremely thin cell (ETC. To measure magnetic signals, we use absorption and very low laser powers, which might be appealing for modern fabrication techniques. A portable, fully automated device was constructed.

  10. Surface magnetic contribution in zinc ferrite thin films studied by element- and site-specific XMCD hysteresis-loops

    Science.gov (United States)

    Mendoza Zélis, P.; Pasquevich, G. A.; Salcedo Rodríguez, K. L.; Sánchez, F. H.; Rodríguez Torres, C. E.

    2016-12-01

    Element- and site-specific magnetic hysteresis-loops measurements on a zinc ferrite (ZnFe2O4) thin film were performed by X-ray magnetic circular dichroism. Results show that iron in octahedral and tetrahedral sites of spinel structure are coupled antiferromagnetically between them, and when magnetic field is applied the magnetic moment of the ion located at octahedral sites aligns along the field direction. The magnetic measurements reveal a distinctive response of the surface with in-plane anisotropy and an effective anisotropy constant value of 12.6 kJ/m3. This effective anisotropy is due to the combining effects of demagnetizing field and, volume and surface magnetic anisotropies KV =3.1 kJ/m3 and KS =16 μJ/m2.

  11. Model of orbital populations for voltage-controlled magnetic anisotropy in transition-metal thin films

    Science.gov (United States)

    Zhang, Jia; Lukashev, Pavel V.; Jaswal, Sitaram S.; Tsymbal, Evgeny Y.

    2017-07-01

    Voltage-controlled magnetic anisotropy (VCMA) is an efficient way to manipulate the magnetization states in nanomagnets and is promising for low-power spintronic applications. The underlying physical mechanism for VCMA is known to involve a change in the d orbital occupation on the transition-metal interface atoms with an applied electric field. However, a simple qualitative picture of how this occupation controls the magnetocrystalline anisotropy (MCA) and even why in certain cases the MCA has the opposite sign remains elusive. In this paper, we exploit a simple model of orbital populations to elucidate a number of features typical for the interface MCA, and the effect of the electric field on it, for 3 d transition-metal thin films used in magnetic tunnel junctions. We find that in all considered cases, including the Fe(001) surface, clean F e1 -xC ox(001 ) /MgO interface, and oxidized Fe(001)/MgO interface, the effects of alloying and the electric field enhance the MCA energy with electron depletion, which is largely explained by the occupancy of the minority-spin dx z ,y z orbitals. However, the hole-doped Fe(001) exhibits an inverse VCMA in which the MCA enhancement is achieved when electrons are accumulated at the Fe (001)/MgO interface with the applied electric field. In this regime, we predict a significantly enhanced VCMA that exceeds 1 pJ/Vm. Realizing this regime experimentally may be favorable for the practical purpose of voltage-driven magnetization reversal.

  12. The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

    KAUST Repository

    Venkatesh, S.

    2016-03-24

    We studied the nature of magnetic ordering in Mn-doped ZnO thin films that exhibited ferromagnetism at 300 K and superparamagnetism at 5 K. We directly inter-related the magnetisation and magnetoresistance by invoking the polaronpercolation theory and variable range of hopping conduction below the metal-to-insulator transition. By obtaining a qualitative agreement between these two models, we attribute the ferromagnetism to the s-d exchange-induced spin splitting that was indicated by large positive magnetoresistance (∼40 %). Low temperature superparamagnetism was attributed to the localization of carriers and non-interacting polaron clusters. This analysis can assist in understanding the presence or absence of ferromagnetism in doped/un-doped ZnO.

  13. MICROWAVE PERMEABILITY SPECTRA OF SPUTTERED Fe-Co-B SOFT MAGNETIC THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Permeability characteristics of sputtered soft magnetic Fe40 Co40B20 thin films are investigated in the range of O. 5 to 5 GHz by a shortened microstrip transmission line perturbation method. Excellent microwave permeability is achieved at O.4 Pa argon pressure: fr is 3.32 GHz, the real and imaginary part of permeability at 0.5 GHz are 104 and 61, respectively. In addition, the thickness effect on permeability is also studied. The minimum damping can be achieved at the thinnest film. Different sources contributed to in-plane anisotropy are discussed briefly. The deviation between the peak frequency of the imaginary part and the zero-crossing frequency of the real part of permeability is also presented.

  14. Microwave Magnetic Properties of Laminates with Thin FeCoBSi Films

    Institute of Scientific and Technical Information of China (English)

    LU Haipeng; JIANG Yongjun; YANG Jing; DENG Longjiang

    2011-01-01

    The microwave permeability of laminated composites based on thin FeCoBSi films was unoer study.The level of permeability increased with increasing of the ferromagnetic inclusions in the laminates.The intrinsic permeability spectra of ferromagnetic inclusion are parametrically reconstructed.The obtained parameters of magnetic resonance were specially analyzed.To avoid the effect of eddy current and to obtain large-volume fractions of ferromagnetic constituent,laminates consisting of alternating FeCoBSi/SiO2 multilayers and mylar substrates were also investigated.For the same volume fractions of ferromagnetic constituent (8.7%),laminates based on multi-layered films are found to possess higher values of permeability than those based on one-layered films.

  15. Magnetism and transport properties of α-Mn structure Mn3Ge thin film

    Science.gov (United States)

    Dung, Dang Duc; Feng, Wuwei; Shin, Yooleemi; Cho, Sunglae

    2011-04-01

    We have newly synthesized the α-Mn structured Mn3Ge thin films on GaAs(001) substrate. The single phase Mn3Ge film was grown at a growth temperature of 150 °C, while the secondary phase was observed above a growth temperature of 250 °C. The Mn3Ge films exhibited ferrimagnetism with a Curie temperature of 334 K. The saturation magnetizations were 255.9 and 313.8 emu/cm3 and the corresponding coercive fields were 453 and 1166 Oe at 10 K for the samples grown at 150 and 300 °C, respectively. The ferrimagnetism was confirmed by the anomalous Hall effect data.

  16. Temperature dependence of perpendicular magnetic anisotropy in CoFeB thin films

    Science.gov (United States)

    Fu, Yu; Barsukov, I.; Li, Jing; Gonçalves, A. M.; Kuo, C. C.; Farle, M.; Krivorotov, I. N.

    2016-04-01

    We study perpendicular magnetic anisotropy in thin films of Ta/Co20Fe60B20/MgO by ferromagnetic resonance and find a linear temperature dependence for the first and second order uniaxial terms from 5 to 300 K. Our data suggest the possible hybridization of Fe-O orbitals at the CoFeB/MgO interface for the origin of the first order anisotropy. However, we also find that non-interfacial contributions to the anisotropy are present. An easy-cone anisotropy is found for the entire temperature range in the narrow region of film thicknesses around the spin reorientation transition 1.2-1.35 nm.

  17. Growth, structure and magnetic properties of magnetron sputtered FePt thin films

    Energy Technology Data Exchange (ETDEWEB)

    Cantelli, Valentina

    2010-07-01

    The L1{sub 0} FePt phase belongs to the most promising hard ferromagnetic materials for high density recording media. The main challenges for thin FePt films are: (i) to lower the process temperature for the transition from the soft magnetic A1 to the hard magnetic L1{sub 0} phase, (ii) to realize c-axes preferential oriented layers independently from the substrate nature and (iii) to control layer morphology supporting the formation of FePt-L1{sub 0} selforganized isolated nanoislands towards an increase of the signal-to-noise ratio. In this study, dc magnetron sputtered FePt thin films on amorphous substrates were investigated. The work is focused on the correlation between structural and magnetic properties with respect to the influence of deposition parameters like growth mode (cosputtering vs. layer - by - layer) and the variation of the deposition gas (Ar, Xe) or pressure (0.3-3 Pa). In low-pressure Ar discharges, high energetic particle impacts support vacancies formation during layer growth lowering the phase transition temperature to (320{+-}20) C. By reducing the particle kinetic energy in Xe discharges, highly (001) preferential oriented L1{sub 0}-FePt films were obtained on a-SiO{sub 2} after vacuum annealing. L1{sub 0}-FePt nano-island formation was supported by the introduction of an Ag matrix, or by random ballistic aggregation and atomic self shadowing realized by FePt depositions at very high pressure (3 Pa). The high coercivity (1.5 T) of granular, magnetic isotropic FePt layers, deposited in Ar discharges, was measured with SQUID magnetometer hysteresis loops. For non-granular films with (001) preferential orientation the coercivity decreased (0.6 T) together with an enhancement of the out-of- plane anisotropy. Nanoislands show a coercive field close to the values obtained for granular layers but exhibit an in-plane easy axis due to shape anisotropy effects. An extensive study with different synchrotron X-ray scattering techniques, mainly

  18. Magnetism switching and band-gap narrowing in Ni-doped PbTiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Wenliang; Yu, Lu; Yang, Pingxiong, E-mail: pxyang@ee.ecnu.edu.cn; Chu, Junhao [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Deng, Hongmei [Instrumental Analysis and Research Center, Institute of Materials, Shanghai University, 99 Shangda Road, Shanghai 200444 (China)

    2015-05-21

    Ions doping-driven structural phase transition accompanied by magnetism switching and band-gap narrowing effects has been observed in PbTi{sub 1−x}Ni{sub x}O{sub 3−δ} (xPTNO, x = 0.00, 0.06, and 0.33) thin films. With the increase of x, the xPTNO thin films exhibit not only a phase transition from the pseudotetragonal structure to a centrosymmetric cubic structure but also a drastic decrease of grain size. Moreover, the as-grown Ni-doped PbTiO{sub 3} (PTO) thin films show obvious room-temperature ferromagnetism and an increased saturation magnetization with increasing the Ni content, in contrast to undoped PTO, which shows diamagnetism. A bound magnetic polaron model was proposed to understand the observed ferromagnetic behavior of PTO-derived perovskite thin films. Furthermore, the 0.33PTNO thin film presents a narrowed band-gap, much smaller than that of PTO, which is attributed to new states of both the highest occupied molecular orbital and the lowest unoccupied molecular orbital in an electronic structure with the presence of Ni. These findings may open up a route to explore promising perovskite oxides as candidate materials for use in multiferroics and solar-energy devices.

  19. Preparation and Characterization of Silver Liquid Thin Films for Magnetic Fluid Deformable Mirror

    Directory of Open Access Journals (Sweden)

    Lianchao Zhang

    2015-01-01

    Full Text Available Silver liquid thin film, formed by silver nanoparticles stacking and spreading on the surface of the liquid, is one of the important parts of magnetic fluid deformable mirror. First, silver nanoparticles were prepared by liquid phase chemical reduction method using sodium citrate as reducing agent and stabilizer and silver nitrate as precursor. Characterization of silver nanoparticles was studied using X-ray diffractometer, UV-vis spectrophotometer, and transmission electron microscope (TEM. The results showed that silver nanoparticles are spherical and have a good monodispersity. Additionally, the effect of the reaction conditions on the particle size of silver is obvious. And then silver liquid thin films were prepared by oil-water two-phase interface technology using as-synthesized silver nanoparticles. Properties of the film were investigated using different technology. The results showed that the film has good reflectivity and the particle size has a great influence on the reflectivity of the films. SEM photos showed that the liquid film is composed of multilayer silver nanoparticles. In addition, stability of the film was studied. The results showed that after being stored for 8 days under natural conditions, the gloss and reflectivity of the film start to decrease.

  20. Thin Co/Ni-based bottom pinned spin-transfer torque magnetic random access memory stacks with high annealing tolerance

    Science.gov (United States)

    Tomczak, Y.; Swerts, J.; Mertens, S.; Lin, T.; Couet, S.; Liu, E.; Sankaran, K.; Pourtois, G.; Kim, W.; Souriau, L.; Van Elshocht, S.; Kar, G.; Furnemont, A.

    2016-01-01

    Spin-transfer torque magnetic random access memory (STT-MRAM) is considered as a replacement for next generation embedded and stand-alone memory applications. One of the main challenges in the STT-MRAM stack development is the compatibility of the stack with CMOS process flows in which thermal budgets up to 400 °C are applied. In this letter, we report on a perpendicularly magnetized MgO-based tunnel junction (p-MTJ) on a thin Co/Ni perpendicular synthetic antiferromagnetic layer with high annealing tolerance. Tunnel magneto resistance (TMR) loss after annealing occurs when the reference layer loses its perpendicular magnetic anisotropy due to reduction of the CoFeB/MgO interfacial anisotropy. A stable Co/Ni based p-MTJ stack with TMR values of 130% at resistance-area products of 9 Ω μm2 after 400 °C anneal is achieved via moment control of the Co/Ta/CoFeB reference layer. Thinning of the CoFeB polarizing layer down to 0.8 nm is the key enabler to achieve 400 °C compatibility with limited TMR loss. Thinning the Co below 0.6 nm leads to a loss of the antiferromagnetic interlayer exchange coupling strength through Ru. Insight into the thickness and moment engineering of the reference layer is displayed to obtain the best magnetic properties and high thermal stability for thin Co/Ni SAF-based STT-MRAM stacks.

  1. The origin of magnetism in transition metal-doped ZrO2 thin films: Experiment and theory

    KAUST Repository

    Hong, Nguyenhoa

    2013-10-04

    We have investigated the magnetic properties of Fe/Co/Ni-doped ZrO 2 laser ablated thin films in comparison with the known results of Mn-doped ZrO2, which is thought to be a promising material for spintronics applications. It is found that doping with a transition metal can induce room temperature ferromagnetism in \\'fake\\' diamond. Theoretical analysis based on density functional theory confirms the experimental measurements, by revealing that the magnetic moments of Mn- and Ni-doped ZrO2 thin films are much larger than that of Fe- or Co-doped ZrO2 thin films. Most importantly, our calculations confirm that Mn- and Ni-doped ZrO2 show a ferromagnetic ground state in comparison to Co- and Fe-doped ZrO 2, which favor an antiferromagnetic ground state. © 2013 IOP Publishing Ltd.

  2. Out-of-Plane Magnetic Anisotropy and Microwave Permeability of Magnetoelastic FeCoSiB Amorphous Thin Films

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The amorphous magnetoelastic Fe66Co17Si1B6 thin films have been deposited by dc magnetron sputtering. A lot of "nano-trenches" have been observed on the film surfaces by AFM. The permeability of amorphous Fe66Co17Si1B6 thin films was measured within the frequency range of 0.6GHz-10.2 GHz. The ferromagnetic resonance frequency was found to be 1.2 GHz. MFM shows that the domain of thin film is a maze-type pattern, which indicates that an out-of-plane magnetic anisotropy exists. The out-of-plane anisotropy is believed due to the stress-induced magnetic anisotropy. It can be inferred that the internal stress is tensile stress and normal to the film plane.

  3. Ferrimagnetic Tb-Fe Alloy Thin Films: Composition and Thickness Dependence of Magnetic Properties and All-Optical Switching

    Directory of Open Access Journals (Sweden)

    Birgit eHebler

    2016-02-01

    Full Text Available Ferrimagnetic rare earth - transition metal Tb-Fe alloy thin films exhibit a variety of different magnetic properties, which depends strongly on composition and temperature. In this study, first the influence of the film thickness (5 - 85 nm on the sample magnetic properties was investigated in a wide composition range between 15 at.% and 38 at.% of Tb. From our results, we find that the compensation point, remanent magnetization, and magnetic anisotropy of the Tb-Fe films depend not only on the composition but also on the thickness of the magnetic film up to a critical thickness of about 20-30 nm. Beyond this critical thickness, only slight changes in magnetic properties are observed. This behavior can be attributed to a growth-induced modification of the microstructure of the amorphous films, which affects the short range order. As a result, a more collinear alignment of the distributed magnetic moments of Tb along the out-of-plane direction with film thickness is obtained. This increasing contribution of the Tb sublattice magnetization to the total sample magnetization is equivalent to a sample becoming richer in Tb and can be referred to as an effective composition. Furthermore, the possibility of all-optical switching, where the magnetization orientation of Tb-Fe can be reversed solely by circularly polarized laser pulses, was analyzed for a broad range of compositions and film thicknesses and correlated to the underlying magnetic properties.

  4. Out-of-plane magnetic domain structure in a thin film of La0.67Sr0.33MnO3 on SrTiO3 (001) observed by magnetic force microscopy

    NARCIS (Netherlands)

    Houwman, E.P.; Maris, G.; De Luca, G.M.; Niemann, N.; Rijnders, G.; Blank, D.H.A.; Speller, S.

    2008-01-01

    The room temperature out-of-plane magnetization of epitaxial thin films of La0.67Sr0.33MnO3 on SrTiO3 (001) has been investigated with magnetic force microscopy, using magnetic tips with very small coercivity, relative to the film. A clear magnetic pattern in the form of a checkerboard, with domain

  5. Effect of chromium interlayer on magnetic exchange coupling of SmCo/Cr/TbFeCo multilayer thin films

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; HUANG Zhixin; LAN Zhigao; CUI Zengli; GUO Jihua; CHENG Weiming; YANG Xiaofei

    2008-01-01

    A series of SmCo/Cr/TbFeCo multilayer thin films with perpendicular anisotropy were prepared by RF- magnetron sputtering system, and the effects of Cr interlayer thickness on magnetic properties and interlayer exchange coupling were investigated. It was found that the magnetic properties varied with the thickness of Cr interlayer, especially the values of saturation magnetization Ms and the coercivity Hc fluctuated periodically with the thickness of Cr interlayer. STM images revealed that the variation of coercivity Hc was attributed to the microstructure change of SmCo layer influenced by Cr interlayer, and the variation of Ms was related to interlayer exchange coupling.

  6. X-ray absorption spectroscopy and magnetic circular dichroism studies of L10-Mn-Ga thin films

    OpenAIRE

    Glas, M; Sterwerf, C.; Schmalhorst, J.M.; Ebke, D.; Jenkins, C.; Arenholz, E.; Reiss, G.

    2013-01-01

    Tetragonally distorted \\(\\rm{Mn}_{3-x}\\rm{Ga}_x\\) thin films with \\(0.1< x < 2\\) show a strong perpendicular magnetic anisotropy and low magnetization and thus have the potential to serve as electrodes in spin transfer torque magnetic random access memory. Because a direct capping of these films with MgO is problematic due to oxide formation, we examined the influence of a CoFeB interlayer, and of two different deposition methods for the MgO barrier on the formation of interfacial MnO for \\(\\...

  7. Nonequilibrium critical behavior of magnetic thin films grown in a temperature gradient

    Science.gov (United States)

    Candia, Julián; Albano, Ezequiel V.

    2012-08-01

    We investigate the irreversible growth of (2 + 1)-dimensional magnetic thin films under the influence of a transverse temperature gradient, which is maintained by thermal baths across a direction perpendicular to the direction of growth. Therefore, different longitudinal layers grow at different temperatures between T1 and T2, where {T}_{1}\\lt {T}_{{c}}^{{hom}}\\lt {T}_{2} and {T}_{{c}}^{{hom}}=0.6 9(1) is the critical temperature of films grown in homogeneous thermal baths. We find a far-from-equilibrium continuous order-disorder phase transition driven by the thermal bath gradient. We characterize this gradient-induced critical behavior by means of standard finite-size scaling procedures, which lead to the critical temperature Tc = 0.84(2) and a new universality class consistent with the set of critical exponents ν = 3/2, γ = 5/2, and β = 1/4. In order to gain further insight into the effects of the temperature gradient, we also develop a bond model that captures the magnetic film’s growth dynamics. Our findings show that the interplay of geometry and thermal bath asymmetries leads to growth bond flux asymmetries and the onset of transverse ordering effects that explain qualitatively the shift observed in the critical temperature. The relevance of these mechanisms is further confirmed by a finite-size scaling analysis of the interface width, which shows that the growing sites of the system define a self-affine interface.

  8. Modification of the Interface Nanostructure and Magnetic Properties in Nd-Fe-B Thin Films.

    Science.gov (United States)

    Koike, Kunihiro; Kusano, Takanao; Ogawa, Daisuke; Kobayashi, Keisuke; Kato, Hiroaki; Oogane, Mikihiko; Miyazaki, Takamichi; Ando, Yasuo; Itakura, Masaru

    2016-12-01

    The effects of Nd2Fe14B grain size and Nd coating on the coercivity in sputter-deposited Nd-Fe-B/Nd thin films have been investigated in order to gain an insight into the coercivity mechanism of Nd-Fe-B magnets. Highly textured Nd2Fe14B particles were grown successfully on the MgO(100) single-crystal substrate with the Mo underlayer. As the Nd-Fe-B layer thickness t NFB was decreased from 70 to 5 nm, the coercivity H c increased gradually from 6.5 to 16 kOe. By depositing the Nd overlayer onto these films and post-annealing at 500 °C, the H c value further increased from 17.5 kOe (t NFB=70 nm) to 26.2 kOe (t NFB=5 nm). The amount of H c increase by the combination of the Nd coating and post-annealing was about 10 kOe irrespective of the t NFB value. These results therefore suggest an independence of size and interface effects on the coercivity of Nd-Fe-B magnets.

  9. Structural, electronic, and magnetic properties of perpendicularly magnetised Mn2RhSn thin films

    Science.gov (United States)

    Meshcheriakova, Olga; Köhler, Albrecht; Ouardi, Siham; Kondo, Yukio; Kubota, Takahide; Chandra, Shekhar; Karel, Julie; Barbosa, Carlos V.; Stinshoff, Rolf; Sahoo, Roshnee; Ueda, Shigenori; Ikenaga, Eiji; Mizukami, Shigemi; Chadov, Stanislav; Ebke, Daniel; Fecher, Gerhard H.; Felser, Claudia

    2015-04-01

    Epitaxial thin films of Mn2RhSn were grown on a MgO(0 0 1) substrate by magnetron co-sputtering of the constituents. An optimised range of temperature for heat treatment was used to stabilise the tetragonal structure and to prevent the capping Rh layer from diffusing into the Heusler layer. Electronic and magnetic properties were analysed by hard x-ray photoelectron spectroscopy as well as field- and temperature-dependent Hall and resistivity measurements. The measured valence spectra are in good agreement with the calculated density of states. The measured saturation magnetisation corresponds to a magnetic moment of 1 μB in the primitive cell. The magnetisation measurements revealed an out-of-plane anisotropy energy of 89 kJ m-3 and a maximum energy product of 3.3 kJ m-3. The magnetoresistance ratio is 2% for fields of 9 T. The lattice parameter of the compound has a very small mismatch with MgO, which makes it promising for coherent electron tunnelling phenomena.

  10. Giant magnetoelectric effect in thin magnetic films utilizing inter-ferroelectric transitions

    Science.gov (United States)

    Finkel, Peter; Staruch, Margo

    There has recently been much interest to multiferroic magnetoelectric composites based on relaxor ferroelectric single crystals as potential candidates for devices such as magnetic field sensors, energy harvesters, or transducers. Large magnetoelectric coupling coefficient is prerequisite for superior device performance in a broad range of frequencies and functioning conditions. In magnetoelectric heterostructures based on ternary relaxors Pb(In1/2Nb1/2) O3-Pb(Mg1/3Nb2/3) O3-PbTiO3 (PIN-PMN-PT) crystal better operational range and temperature stability as compared to binary relaxors can be achieved. Giant linear converse magnetoelectric coupling up to 2 x 10-6 s m-1 were observed in heterostructural composites with multilayered FeCo/Ag deposited on (011) PIN-PMN-PT crystals. Further enhancement of magnetoelectric coupling is demonstrated by utilizing inter-ferroelctric rhombohedral - orthorhombic phase transitions in PIN-PMN-PT Mechanical clamping was a precondition to utilize this inter-ferroelectric transition mode to bring the crystal to a point just below its transformation threshold when very small perturbations at the input will cause large swings at the output generating a sharp uniaxial increase in strain (~0.5 %) and polarization change, giving rise to nonlinear effects. Details of these results and their implications will be presented. Giant magnetoelectric effect in thin magnetic fillms utilizing inter-ferroelectric transitions.

  11. Magnetic Interactions in Strained Multiferroic EuTiO3 Thin Films

    Science.gov (United States)

    Freeland, J. W.; Ke, X.; Lee, J. H.; Ryan, P.; Kim, J. W.; Fennie, C. J.; Schiffer, P.; Schlom, D. G.

    2010-03-01

    Bulk EuTiO3 possesses a paraelectric and antiferromagnetic ground but it has been predicted that under tensile strain the system would show spontaneous ferromagnetic and ferroelectric order[1]. Here we present a study of the magnetic interactions in thin films of EuTiO3 grown on SrTiO3(001) and DyScO3(110) substrates by reactive molecular-beam epitaxy (MBE). Using magnetometry, x-ray magnetic circular dichroism, and magneto-capacitance, there clear evidence of ferromagnetic order under tensile strain while the unstrained films are anti-ferromagnetic. These results will be discussed in the context of the predicted behavior. Work at Argonne, including the Advanced Photon, is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. [1] C.J. Fennie and K.M. Rabe, Phys. Rev. Lett. 97, 267602 (2006)].

  12. Ultra-thin Low-Frequency Broadband Microwave Absorber Based on Magnetic Medium and Metamaterial

    Science.gov (United States)

    Cheng, Yongzhi; He, Bo; Zhao, Jingcheng; Gong, Rongzhou

    2017-02-01

    An ultra-thin low-frequency broadband microwave absorber (MWA) based on a magnetic rubber plate (MRP) and cross-shaped structure (CSS) metamaterial (MM) was presented numerically and experimentally. The designed composite MWA is consisted of the MRP, CSS resonator, dielectric substrate and metallic background plane. The low-frequency absorption can be easily adjusted by tuning the geometric parameter of the CSS MM and the thickness of MPR. A bandwidth (i.e. the reflectance is below -10 dB) from 2.5 GHz to 5 GHz can be achieved with the total thickness of about 2 mm in experiments. The broadband absorption is attributed to the overlap of two resonant absorption peaks originated from MRP and CSS MM, respectively. More importantly, the thickness of the composite WMA is much thinner ( λ/40; λ is the operation center frequency), which could operate well at wide incidence angles for both transverse electric and transverse magnetic waves. Thus, it can be expected that our design will be applicable in the area of eliminating microwave energy and electromagnetic stealth.

  13. Exponentially decaying magnetic coupling in sputtered thin film FeNi/Cu/FeCo trilayers

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Yajun, E-mail: yajun.wei@angstrom.uu.se; Akansel, Serkan; Thersleff, Thomas; Brucas, Rimantas; Lansaker, Pia; Leifer, Klaus; Svedlindh, Peter [Department of Engineering Sciences, Uppsala University, 75121 Uppsala (Sweden); Harward, Ian; Celinski, Zbigniew [Department of Physics, University of Colorado, Colorado Springs, Colorado 80918 (United States); Ranjbar, Mojtaba; Dumas, Randy K. [Department of Physics, University of Gothenburg, 41296 Gothenburg (Sweden); Jana, Somnath; Pogoryelov, Yevgen; Karis, Olof [Department of Physics and Astronomy, Uppsala University, 75120 Uppsala (Sweden); Åkerman, Johan [Department of Physics, University of Gothenburg, 41296 Gothenburg (Sweden); Department of Applied Physics and Microelectronics, Royal Institute of Technology, 10044 Kista (Sweden)

    2015-01-26

    Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO{sub 2} substrates have been studied. While the thicknesses of the FeNi and FeCo layers were kept constant at 100 Å, the thickness of the Cu spacer was varied from 5 to 50 Å. Both hysteresis loop and ferromagnetic resonance results indicate that all films are ferromagnetically coupled. Micromagnetic simulations well reproduce the ferromagnetic resonance mode positions measured by experiments, enabling the extraction of the coupling constants. Films with a thin Cu spacer are found to be strongly coupled, with an effective coupling constant of 3 erg/cm{sup 2} for the sample with a 5 Å Cu spacer. The strong coupling strength is qualitatively understood within the framework of a combined effect of Ruderman-Kittel-Kasuya-Yosida and pinhole coupling, which is evidenced by transmission electron microscopy analysis. The magnetic coupling constant surprisingly decreases exponentially with increasing Cu spacer thickness, without showing an oscillatory thickness dependence. This is partially connected to the substantial interfacial roughness that washes away the oscillation. The results have implications on the design of multilayers for spintronic applications.

  14. Magnetic, transport, and structural properties of SrRuO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Majcher, A. M. [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Institute of Physics, Jagiellonian University Krakow, Krakow (Poland); Rode, K.; Coey, J. M. D.; Stamenov, P., E-mail: stamenov.plamen@tcd.ie [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland)

    2014-05-07

    Thin films of the oxide ferromagnetic metal SrRuO{sub 3} (SRO) are studied, in view of their potential use within oxide-based spin electronic devices. Here, their epitaxial growth on Si-compatible SrTiO{sub 3} substrates is demonstrated by pulsed laser deposition. Detail on their initial, structural, magnetic, and magnetotransport characterisation is also provided. In particular, resistivity and Hall data are interpreted within a two/three carrier model, above T{sub C.} Below T{sub C}, some information about the anisotropy of the Fermi surface effective elipsoids (∼1:4) is recovered. The low-temperature saturation magnetisation approaches 1 μ{sub B}/Ru, with an uniaxial anisotropy of above 0.6 MJm{sup –3}. Despite its low T{sub C} = 160 K, and in view of its relatively low carrier mobility, it is reasoned that SRO could be utilized as the electrode layer in low-temperature all-oxide-MTJ (Magnetic Tunnel Junction) demonstrators and as a seed layer for other ferromagnetic oxides, at and above room temperature.

  15. Wireless thin film transistor based on micro magnetic induction coupling antenna

    Science.gov (United States)

    Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

    2015-12-01

    A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT).

  16. Tuning of magnetic properties for epitaxial Y2NiMnO6 thin film: Substrate is crucial

    Science.gov (United States)

    Xie, Changzheng; Shi, Lei

    2016-10-01

    The effects of epitaxial strain induced by lattice mismatch and substrate type on the structure and magnetic properties of Y2NiMnO6 thin films have been systematically investigated. Y2NiMnO6 thin films grown on (001)-oriented LaAlO3 (LAO), (La,Sr)(Al,Ta)O3 (LSAT), and SrTiO3 (STO) substrates with varying film thickness are obtained by a simple polymer assisted deposition method. X-ray diffraction and Raman scattering observations indicate that the single-phase epitaxial films are successfully obtained. By magnetic measurements, it is found that all the films show an obvious ferromagnetic transition with a lower transition temperatures (Tc) than that of the Y2NiMnO6 bulk. With the biaxial tensile strain decreasing or the film thickness increasing, the Tc of the film increases. Besides, due to the different strain states of the films and the different surface migrations of the substrates, the structure and magnetic properties show a strong dependence on the type of substrate. It is suggested that the biaxial tensile strain and substrate type have crucial effects on the structure, magnetic properties and the related Tc of the thin film, which can be utilized to engineer the magnetic properties of the films and the related ferroelectricity.

  17. Soft x-ray ptychography studies of nanoscale magnetic and structural correlations in thin SmCo{sub 5} films

    Energy Technology Data Exchange (ETDEWEB)

    Shi, X. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of Oregon, Eugene, Oregon 97401 (United States); Fischer, P. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Santa Cruz, California 94056 (United States); Neu, V.; Elefant, D. [IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069 Dresden (Germany); Lee, J. C. T.; Kevan, S. D., E-mail: SDKevan@lbl.gov [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of Oregon, Eugene, Oregon 97401 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Shapiro, D. A.; Farmand, M.; Tyliszczak, T.; Marchesini, S.; Roy, S. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Shiu, H.-W. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China)

    2016-02-29

    High spatial resolution magnetic x-ray spectromicroscopy at x-ray photon energies near the cobalt L{sub 3} resonance was applied to probe an amorphous 50 nm thin SmCo{sub 5} film prepared by off-axis pulsed laser deposition onto an x-ray transparent 200 nm thin Si{sub 3}N{sub 4} membrane. Alternating gradient magnetometry shows a strong in-plane anisotropy and an only weak perpendicular magnetic anisotropy, which is confirmed by magnetic transmission soft x-ray microscopy images showing over a field of view of 10 μm a primarily stripe-like domain pattern but with local labyrinth-like domains. Soft x-ray ptychography in amplitude and phase contrast was used to identify and characterize local magnetic and structural features over a field of view of 1 μm with a spatial resolution of about 10 nm. There, the magnetic labyrinth domain patterns are accompanied by nanoscale structural inclusions that are primarily located in close proximity to the magnetic domain walls. Our analysis suggests that these inclusions are nanocrystalline Sm{sub 2}Co{sub 17} phases with nominally in-plane magnetic anisotropy.

  18. Room-Temperature Magnetic and Magneto-Optical Properties of Sr2FeMoO6 Thin Films

    Science.gov (United States)

    Asano, Hidefumi; Osugi, Masahiro; Kohara, Yasuhiro; Higashida, Daisuke; Matsui, Masaaki

    2001-08-01

    Epitaxial thin films of a half-metallic ferromagnet Sr2FeMoO6 have been grown on (001) SrTiO3, and MgO substrates by magnetron sputtering in Ar+H2 mixture gas. Their structural, magnetic, magneto-optical and transport properties at room temperature were investigated and compared. Large difference has been observed especially in the magnetic and magneto-optical properties between thin films on SrTiO3 and MgO@. The films on SrTiO3 exhibited stronger out-of-plane magnetic anisotropy and larger complex polar Kerr effect with a rotation θk up to -0.32\\circ at 1.6 eV and RT@. The observed difference in the properties of the films on the two substrates can be interpreted in terms of the structural disorder.

  19. Strong out-of-plane magnetic anisotropy in ion irradiated anatase TiO2 thin films

    Directory of Open Access Journals (Sweden)

    M. Stiller

    2016-12-01

    Full Text Available The temperature and field dependence of the magnetization of epitaxial, undoped anatase TiO2 thin films on SrTiO3 substrates was investigated. Low-energy ion irradiation was used to modify the surface of the films within a few nanometers, yet with high enough energy to produce oxygen and titanium vacancies. The as-prepared thin film shows ferromagnetism which increases after irradiation with low-energy ions. An optimal and clear magnetic anisotropy was observed after the first irradiation, opposite to the expected form anisotropy. Taking into account the experimental parameters, titanium vacancies as di-Frenkel pairs appear to be responsible for the enhanced ferromagnetism and the strong anisotropy observed in our films. The magnetic impurities concentrations was measured by particle-induced X-ray emission with ppm resolution. They are ruled out as a source of the observed ferromagnetism before and after irradiation.

  20. Structural and magnetic properties of zinc ferrite thin films irradiated by 90 keV neon ions

    Science.gov (United States)

    Gafton, E. V.; Bulai, G.; Caltun, O. F.; Cervera, S.; Macé, S.; Trassinelli, M.; Steydli, S.; Vernhet, D.

    2016-08-01

    The effects of 90 keV neon beam irradiation on the structure and magnetic properties of zinc ferrite thin films have been investigated through several methods, namely, X-ray diffraction technique, Vibrating Sample and SQUID magnetometers. Beforehand, the pristine have also been characterized using profilometry and microscopy techniques. In particular single-phase formation of the thin films deposited on monocrystalline Si (111) substrate by pulsed laser deposition technique was confirmed. Crystal lattice, coercivity, saturation magnetization have been studied for the first time, as a function of ion penetration depth and irradiation fluence. The chemical composition and the crystallinity of the films are not affected with the ion impact acting as a mechanical stress relief. On the contrary, both magnetization and coercivity are sensitive to Neq+ ion irradiation and exhibit different behaviours depending on the ion fluence range.

  1. Surface magnetic contribution in zinc ferrite thin films studied by element- and site-specific XMCD hysteresis-loops

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza Zélis, P.; Pasquevich, G.A. [IFLP-CCT-La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Departamento de Ciencias Básicas, Facultad de Ingeniería, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Salcedo Rodríguez, K.L.; Sánchez, F.H. [IFLP-CCT-La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Rodríguez Torres, C.E., E-mail: torres@fisica.unlp.edu.ar [IFLP-CCT-La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina)

    2016-12-01

    Element- and site-specific magnetic hysteresis-loops measurements on a zinc ferrite (ZnFe{sub 2}O{sub 4}) thin film were performed by X-ray magnetic circular dichroism. Results show that iron in octahedral and tetrahedral sites of spinel structure are coupled antiferromagnetically between them, and when magnetic field is applied the magnetic moment of the ion located at octahedral sites aligns along the field direction. The magnetic measurements reveal a distinctive response of the surface with in-plane anisotropy and an effective anisotropy constant value of 12.6 kJ/m{sup 3}. This effective anisotropy is due to the combining effects of demagnetizing field and, volume and surface magnetic anisotropies K{sub V} =3.1 kJ/m{sup 3} and K{sub S} =16 μJ/m{sup 2}. - Highlights: • Surface magnetic response in ZnFe{sub 2}O{sub 4} film (thickness t ∼57 nm) by XMCD is studied. • Measurements of magnetic moment vs. applied field cycles via XMCD are presented. • Fe{sup 3+} at A- and B-sites are coupled antiferromagnetically between them. • A distinctive response of the surface with in-plane magnetic anisotropy is determined. • Volume and surface magnetic anisotropy are determined: 3.1 kJ/m{sup 3} and 16 μJ/m{sup 2}.

  2. dc and ac magnetic properties of thin-walled Nb cylinders with and without a row of antidots.

    Science.gov (United States)

    Tsindlekht, M I; Genkin, V M; Felner, I; Zeides, F; Katz, N; Gazi, Š; Chromik, Š; Dobrovolskiy, O V; Sachser, R; Huth, M

    2016-06-01

    dc and ac magnetic properties of two thin-walled superconducting Nb cylinders with a rectangular cross-section are reported. Magnetization curves and the ac response were studied on as-prepared and patterned samples in magnetic fields parallel to the cylinder axis. A row of micron-sized antidots (holes) was made in the film along the cylinder axis. Avalanche-like jumps of the magnetization are observed for both samples at low temperatures for magnetic fields not only above H c1, but in fields lower than H c1 in the vortex-free region. The positions of the jumps are not reproducible and they change from one experiment to another, resembling vortex lattice instabilities usually observed for magnetic fields larger than H c1. At temperatures above [Formula: see text] and [Formula: see text] the magnetization curves become smooth for the patterned and the as-prepared samples, respectively. The magnetization curve of a reference planar Nb film in the parallel field geometry does not exhibit jumps in the entire range of accessible temperatures. The ac response was measured in constant and swept dc magnetic field modes. Experiment shows that ac losses at low magnetic fields in a swept field mode are smaller for the patterned sample. For both samples the shapes of the field dependences of losses and the amplitude of the third harmonic are the same in constant and swept field near H c3. This similarity does not exist at low fields in a swept mode.

  3. Raman spectroscopy of atomically thin two-dimensional magnetic iron phosphorus trisulfide (FePS3) crystals

    Science.gov (United States)

    Wang, Xingzhi; Du, Kezhao; Liu, Yu Yang Fredrik; Hu, Peng; Zhang, Jun; Zhang, Qing; Owen, Man Hon Samuel; Lu, Xin; Gan, Chee Kwan; Sengupta, Pinaki; Kloc, Christian; Xiong, Qihua

    2016-09-01

    Metal phosphorous trichalcogenide is an important group of layered two-dimensional (2D) materials with potentially diverse applications in low-dimensional magnetic and spintronic devices. Herein we present a comprehensive investigation on the lattice dynamics and spin-phonon interactions of mechanically exfoliated atomically thin 2D magnetic material—iron phosphorus trisulfide (FePS3) by Raman spectroscopy and first principle calculations. Layer-number and temperature dependent Raman spectroscopy suggests a magnetic persistence in FePS3 even down to monolayer regime through the spin-phonon coupling, while the Néel temperature decreases from 117 K in bulk to 104 K in monolayer sample. Our studies advocate the intriguing magnetic properties in 2D crystals and suggest that FePS3 is a promising candidate material for future magnetic applications.

  4. GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS: Cluster Observation of Electrostatic Solitary Waves around Magnetic Null Point in Thin Current Sheet

    Science.gov (United States)

    Li, Shi-You; Deng, Xiao-Hua; Zhou, Meng; Yuan, Zhi-Gang; Wang, Jing-Fang; Lin, Xi; Lin, Min-Hui; Fu, Song

    2010-01-01

    Electrostatic solitary waves (ESWs) are observed in the vicinity of the magnetic null of the widely studied magnetic reconnection taking place at the near-earth tail when current sheet becomes dramatic thinning during substorm time on 1 October 2001. We use the Imada method for the 2-D reconnection model and study the characteristics of ESWs near the X-line region and the magnetic null points. The result shows that the amplitude of the observed ESWs in the vicinity of X-line region ranges from 0.1 mV/m to 5 mV/m, and the amplitude is larger near the magnetic null points. The generation mechanism and the role of ESWs associated with magnetic reconnection are also discussed.

  5. Low energy Ne ion beam induced-modifications of magnetic properties in MnAs thin films

    Science.gov (United States)

    Trassinelli, M.; Carlsson, L. Bernard; Cervera, S.; Eddrief, M.; Etgens, V. H.; Gafton, E. V.; Lacaze, E.; Lamour, E.; Lévy, A.; Macé, S.; Prigent, C.; Rozet, J.-P.; Steydli, S.; Marangolo, M.; Vernhet, D.

    2017-02-01

    Investigations of the complex behavior of the magnetization of manganese arsenide thin films due to defects induced by irradiation of slow heavy ions are presented. In addition to the thermal hysteresis suppression already highlighted in Trassinelli et al (2014 Appl. Phys. Lett. 104 081906), we report here on new local magnetic features recorded by a magnetic force microscope at different temperatures close to the characteristic sample phase transition. Complementary measurements of the global magnetization in different conditions (applied magnetic field and temperatures) enable the film characterization to be completed. The obtained results suggest that the ion bombardment produces regions where the local mechanical constraints are significantly different from the average, promoting the local presence of magneto-structural phases far from the equilibrium. These regions could be responsible for the thermal hysteresis suppression previously reported, irradiation-induced defects acting as seeds in the phase transition.

  6. A temperature-independent fibre-optic magnetic-field sensor using thin-core fibre tailored fibre Bragg grating

    Science.gov (United States)

    Tian, Qin; Feng, Zhongyao; Rong, Qiangzhou; Wan, Yun; Qiao, Xueguang; Hu, Manli; Yang, Hangzhou; Wang, Ruohui; Shao, Zhihua; Yang, Tingting

    2017-06-01

    A temperature-independent fibre-optic magnetic-field sensor is proposed and demonstrated experimentally. The device consists of a thin-core fibre (TCF) sandwiched in the upstream of a fibre Bragg grating (FBG). Because of the core-mismatch between the TCF and the single-mode fibre (SMF), the core mode is coupled to the cladding modes within the TCF cladding, and parts of them are recoupled back to the leading-in SMF by the downstream FBG. The cladding modes are sensitive to the ambient refractive index (RI), and therefore have the ability to respond to a RI change in the magnetic fluid determined by the ambient magnetic field. The intensities of the cladding-mode resonances are highly sensitive to the magnetic field change, while, in contrast, the resonance wavelengths always remain unchanged. This property can allow the sensor to act as a power-referenced reflection probe for magnetic field measurements.

  7. Electrochemical cell for in situ electrodeposition of magnetic thin films in a superconducting quantum interference device magnetometer.

    Science.gov (United States)

    Topolovec, Stefan; Krenn, Heinz; Würschum, Roland

    2015-06-01

    An electrochemical cell is designed and applied for in situ electrodeposition of magnetic thin films in a commercial SQUID magnetometer system. The cell is constructed in such a way that any parasitic contribution of the cell and of the substrate for electrodeposition to the magnetic moment of the deposited film is reduced to a minimum. A remanent minor contribution is readily taken into account by a proper analysis of the detected signal. Thus, a precise determination of the absolute magnetic moment of the electrodeposited magnetic film during its growth and dissolution is achieved. The feasibility of the cell design is demonstrated by performing Co electrodeposition using cyclic voltammetry. For an average Co film thickness of (35.6 ± 3.0) atomic layers, a magnetic moment per Co atom of (1.75 ± 0.11) μ(B) was estimated, in good agreement with the literature bulk value.

  8. Effect of Ar pressure on the magnetic properties of Fe-Si sub 3 N sub x thin films prepared by co-sputtering

    CERN Document Server

    Yoo, Y G; Kim, W T; Jang, P W; Kim, C S

    2000-01-01

    The magnetic properties of Fe-Si sub 3 N sub x thin films fabricated by a co-sputtering technique were studied by electrical resistivity, magnetometry, and Moessbauer spectroscopy as a function of the Ar pressure. As the Ar pressure increased, the electrical resistivity increased while the saturation magnetization decreased. The temperature and the field dependences of the magnetization of the co-sputtered thin films can be explained by a mixture of ferromagnetic and paramagnetic components. also, the Moessbauer spectra showed good agreement with the magnetization results; the ferromagnetic contribution to the magnetization decreased with increasing Ar pressure.

  9. Chiral magnetic conductivity and surface states of Weyl semimetals in topological insulator ultra-thin film multilayer.

    Science.gov (United States)

    Owerre, S A

    2016-06-15

    We investigate an ultra-thin film of topological insulator (TI) multilayer as a model for a three-dimensional (3D) Weyl semimetal. We introduce tunneling parameters t S, [Formula: see text], and t D, where the former two parameters couple layers of the same thin film at small and large momenta, and the latter parameter couples neighbouring thin film layers along the z-direction. The Chern number is computed in each topological phase of the system and we find that for [Formula: see text], the tunneling parameter [Formula: see text] changes from positive to negative as the system transits from Weyl semi-metallic phase to insulating phases. We further study the chiral magnetic effect (CME) of the system in the presence of a time dependent magnetic field. We compute the low-temperature dependence of the chiral magnetic conductivity and show that it captures three distinct phases of the system separated by plateaus. Furthermore, we propose and study a 3D lattice model of Porphyrin thin film, an organic material known to support topological Frenkel exciton edge states. We show that this model exhibits a 3D Weyl semi-metallic phase and also supports a 2D Weyl semi-metallic phase. We further show that this model recovers that of 3D Weyl semimetal in topological insulator thin film multilayer. Thus, paving the way for simulating a 3D Weyl semimetal in topological insulator thin film multilayer. We obtain the surface states (Fermi arcs) in the 3D model and the chiral edge states in the 2D model and analyze their topological properties.

  10. Chiral magnetic conductivity and surface states of Weyl semimetals in topological insulator ultra-thin film multilayer

    Science.gov (United States)

    Owerre, S. A.

    2016-06-01

    We investigate an ultra-thin film of topological insulator (TI) multilayer as a model for a three-dimensional (3D) Weyl semimetal. We introduce tunneling parameters t S, {{t}\\bot} , and t D, where the former two parameters couple layers of the same thin film at small and large momenta, and the latter parameter couples neighbouring thin film layers along the z-direction. The Chern number is computed in each topological phase of the system and we find that for {{t}\\text{S}},{{t}\\text{D}}>0 , the tunneling parameter {{t}\\bot} changes from positive to negative as the system transits from Weyl semi-metallic phase to insulating phases. We further study the chiral magnetic effect (CME) of the system in the presence of a time dependent magnetic field. We compute the low-temperature dependence of the chiral magnetic conductivity and show that it captures three distinct phases of the system separated by plateaus. Furthermore, we propose and study a 3D lattice model of Porphyrin thin film, an organic material known to support topological Frenkel exciton edge states. We show that this model exhibits a 3D Weyl semi-metallic phase and also supports a 2D Weyl semi-metallic phase. We further show that this model recovers that of 3D Weyl semimetal in topological insulator thin film multilayer. Thus, paving the way for simulating a 3D Weyl semimetal in topological insulator thin film multilayer. We obtain the surface states (Fermi arcs) in the 3D model and the chiral edge states in the 2D model and analyze their topological properties.

  11. Magnetic field stimulated enhancement of the barrier for vortex penetration in bended bridges of thin TaN films

    Energy Technology Data Exchange (ETDEWEB)

    Ilin, Konstantin, E-mail: konstantin.ilin@kit.edu; Siegel, Michael, E-mail: michael.siegel@kit.edu

    2014-08-15

    Highlights: • Critical state in mesoscopic superconducting TaN structures has been studied. • Suppression of the current crowding by magnetic field has been investigated. • Maximum of critical current of bended TaN bridges is at non-zero magnetic field. • The critical current of 90° bended bridges increases by 37% in magnetic field. • Significant bulk pinning is in ultra-thin TaN mesoscopic structures. - Abstract: An increase of the supercurrent density in the vicinity of sharp bends of mesoscopic superconducting strips (the current crowding) leads to a decrease of the potential barrier for vortex penetration and thus to a decrease of the measured critical current I{sub C} of the strip in comparison to the de-pairing critical current. However, it has been shown that the Meissner currents induced by an external magnetic field of appropriate direction reduce the effect of current crowding resulting in an increase of the measured I{sub C} of superconducting mesoscopic structures with bends. We performed a detailed experimental investigation of the dependence of critical current on magnetic field in straight and bended bridges made from thin TaN films. Indeed, in the case of bridges with bends, the critical current reaches a maximum at non-zero magnetic fields which value increases with an increase of the angle of bends.

  12. L10-Ordered Thin Films with High Perpendicular Magnetic Anisotropy for STT-MRAM Applications

    Science.gov (United States)

    Huang, Efrem Yuan-Fu

    The objective of the research conducted herein was to develop L10-ordered materials and thin film stack structures with high perpendicular magnetic anisotropy (PMA) for spin-transfertorque magnetoresistive random access memory (STT-MRAM) applications. A systematic approach was taken in this dissertation, culminating in exchange coupled L1 0-FePt and L10- MnAl heterogeneous structures showing great promise for developing perpendicular magnetic tunnel junctions (pMTJs) with both high thermal stability and low critical switching current. First, using MgO underlayers on Si substrates, sputtered MnAl films were systematically optimized, ultimately producing a Si substrate/MgO (20 nm)/MnAl (30)/Ta (5) film stack with a high degree of ordering and large PMA. Next, noting the incompatibility of insulating MgO underlayers with industrial-scale CMOS processes, attention was turned to using conductive underlayers. TiN was found to excel at promoting growth of L10-MnAl, with optimized films showing improved magnetic properties over those fabricated on MgO underlayers. The use of different post-annealing processes was then studied as an alternative to in situ annealing. Rapid thermal annealing (RTA) was found to produce PMA in films at lower annealing temperatures than tube furnace annealing, but tube furnace annealing produced films with higher maximum PMA than RTA. While annealed samples had lower surface roughness than those ordered by high in situ deposition temperatures, relying solely on annealing to achieve L10-ordering resulted drastically reduced PMA. Finally, heterogeneous L10-ordered FePt/MgO/MnAl film stacks were explored for pMTJs. Film stacks with MgO barrier layers thinner than 2 nm showed significant interdiffusion between the FePt and MnAl, while film stacks with thicker MgO barrier layers exhibited good ordering and high PMA in both the FePt and MnAl films. It is believed that this limitation is caused by the roughness of the underlying FePt, which was thicker

  13. High Temperature Magnetic Properties of Indirect Exchange Spring FePt/M(Cu,C/Fe Trilayer Thin Films

    Directory of Open Access Journals (Sweden)

    Anabil Gayen

    2013-01-01

    Full Text Available We report the investigation of temperature dependent magnetic properties of FePt and FePt(30/M(Cu,C/Fe(5 trilayer thin films prepared by using magnetron sputtering technique at ambient temperature and postannealed at different temperatures. L10 ordering, hard magnetic properties, and thermal stability of FePt films are improved with increasing postannealing temperature. In FePt/M/Fe trilayer, the formation of interlayer exchange coupling between magnetic layers depends on interlayer materials and interface morphology. In FePt/C/Fe trilayer, when the C interlayer thickness was about 0.5 nm, a strong interlayer exchange coupling between hard and soft layers was achieved, and saturation magnetization was enhanced considerably after using interlayer exchange coupling with Fe. In addition, incoherent magnetization reversal process observed in FePt/Fe films changes into coherent switching process in FePt/C/Fe films giving rise to a single hysteresis loop. High temperature magnetic studies up to 573 K reveal that the effective reduction in the coercivity decreases largely from 34 Oe/K for FePt/Fe film to 13 Oe/K for FePt/C(0.5/Fe film demonstrating that the interlayer exchange coupling seems to be a promising approach to improve the stability of hard magnetic properties at high temperatures, which is suitable for high-performance magnets and thermally assisted magnetic recording media.

  14. Nanoscale magnetization reversal caused by electric field-induced ion migration and redistribution in cobalt ferrite thin films.

    Science.gov (United States)

    Chen, Xinxin; Zhu, Xiaojian; Xiao, Wen; Liu, Gang; Feng, Yuan Ping; Ding, Jun; Li, Run-Wei

    2015-04-28

    Reversible nanoscale magnetization reversal controlled merely by electric fields is still challenging at the moment. In this report, first-principles calculation indicates that electric field-induced magnetization reversal can be achieved by the appearance of unidirectional magnetic anisotropy along the (110) direction in Fe-deficient cobalt ferrite (CoFe(2-x)O4, CFO), as a result of the migration and local redistribution of the Co(2+) ions adjacent to the B-site Fe vacancies. In good agreement with the theoretical model, we experimentally observed that in the CFO thin films the nanoscale magnetization can be reversibly and nonvolatilely reversed at room temperature via an electrical ion-manipulation approach, wherein the application of electric fields with appropriate polarity and amplitude can modulate the size of magnetic domains with different magnetizations up to 70%. With the low power consumption (subpicojoule) characteristics and the elimination of external magnetic field, the observed electric field-induced magnetization reversal can be used for the construction of energy-efficient spintronic devices, e.g., low-power electric-write and magnetic-read memories.

  15. Microscopic magnetic properties of an oxygen-doped Tb-Fe thin film by magnetic Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Agui, Akane, E-mail: agui@spring8.or.jp [Quantum Beam Science Directorate, Japan Atomic Energy Agency, SPring-8, Sayo, Hyogo 679-5148 (Japan); Unno, Tomoya; Matsumoto, Sayaka; Suzuki, Kousuke; Sakurai, Hiroshi [Department of Production Science and Technology, Gunma University, Ota, Gunma 373-0057 (Japan); Koizumi, Akihisa [Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297 (Japan)

    2013-11-14

    The magnetic Compton scattering of a Tb{sub 32}Fe{sub 55}O{sub 13} film was measured in order to investigate the microscopic magnetization processes (i.e., the spin moment, orbital moment, and element specific moments). The trend of the spin magnetic moment was the same as that of the total magnetic moment but opposite to the orbital magnetic moment. In the low magnetic field region, the magnetic moments were not perfectly aligned perpendicular to the film surface, and the perpendicular components were found to mainly arise from the magnetic moment of Tb. Oxygen atoms hinder long range magnetic interaction and hence also affect the magnetization process of the magnetic moments of Tb and Fe.

  16. Characterization of dilute magnetic semiconducting transition metal doped ZnO thin films by sol–gel spin coating method

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaprasath, G.; Murugan, R. [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Ravi, G., E-mail: gravicrc@gmail.com [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Mahalingam, T. [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8011 (Japan)

    2014-09-15

    Graphical abstract: - Highlights: • Diluted magnetic semiconducting TM (Ni, Mn, Co) doped ZnO thin films were fabricated by sol–gel spin coating technique. • The XRD analyses revealed that the TM (Ni, Mn, Co) doped ZnO films have hexagonal wurtzite structure. • Photoluminescence and micro-Raman spectra were interpreted for TM (Ni, Mn, Co) doped ZnO thin films. • SEM morphology studies were made for Zn{sub 0.97} Ni{sub 0.03}O, Zn{sub 0.97} Mn{sub 0.03}O and Zn{sub 0.97} Co{sub 0.03}O thin films. • Room temperature ferromagnetism was observed in TM (Ni, Mn, Co) doped ZnO thin films. - Abstract: Pure and transition metal (TM = Ni, Mn, Co) doped zinc oxide (ZnO) thin films were prepared by sol–gel spin coating method with a concentration of 0.03 mol% of transition metals. X-ray diffraction studies revealed the polycrystalline nature of the films with the presence of hexagonal wurtzite structure. UV transmittance spectra showed that all the films are highly transparent in the visible region and in the case of doped ZnO thin films, d–d transition was observed in the violet region due to the existence of crystalline defects and grain boundaries. The optical band gap of the films decreases with increasing orbital occupation numbers of 3d electrons due to the orbital splitting of magnetic ions. Ultraviolet and near-infrared electronic transitions were observed which reveals a strong relationship with the doping of transition metal into ZnO site. The observed luminescence in the green, violet and red regions strongly depends on the doping elements owing to the different oxygen vacancy, oxygen interstitial, and surface morphology. The surface morphology of thin films was investigated by scanning electron microscope (SEM). The energy dispersive X-ray analysis (EDX) confirmed the stoichiometric composition of the TM doped ZnO thin films. Magnetic measurements at room temperature exhibited well defined ferromagnetic features of the thin films.

  17. Depth-dependent magnetism in epitaxial MnSb thin films: effects of surface passivation and cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Aldous J. D.; Sanchez-Hanke C.; Burrows, C.W.; Maskery, I.; Brewer, M.S.; Hase, T.P.A.; Duffy, J.A.; Lees, M. Rs; Decoster, T.; Theis, W.; Quesada, A.; Schmid, A.K.; Bell, G.R.

    2012-03-15

    Depth-dependent magnetism in MnSb(0001) epitaxial films has been studied by combining experimental methods with different surface specificities: polarized neutron reflectivity, x-ray magnetic circular dichroism (XMCD), x-ray resonant magnetic scattering and spin-polarized low energy electron microscopy (SPLEEM). A native oxide {approx}4.5 nm thick covers air-exposed samples which increases the film's coercivity. HCl etching efficiently removes this oxide and in situ surface treatment of etched samples enables surface magnetic contrast to be observed in SPLEEM. A thin Sb capping layer prevents oxidation and preserves ferromagnetism throughout the MnSb film. The interpretation of Mn L{sub 3,2} edge XMCD data is discussed.

  18. X-ray magnetic circular dichroism study of Dy-doped Bi2Te3 topological insulator thin films

    Science.gov (United States)

    Figueroa, A. I.; Baker, A. A.; Harrison, S. E.; Kummer, K.; van der Laan, G.; Hesjedal, T.

    2017-01-01

    Magnetic doping of topological insulators (TIs) is crucial for unlocking novel quantum phenomena, paving the way for spintronics applications. Recently, we have shown that doping with rare earth ions introduces large magnetic moments and allows for high doping concentrations without the loss of crystal quality, however no long range magnetic order was observed. In Dy-doped Bi2Te3 we found a band gap opening above a critical doping concentration, despite the paramagnetic bulk behavior. Here, we present a surface-sensitive x-ray magnetic circular dichroism (XMCD) study of an in situ cleaved film in the cleanest possible environment. The Dy M4,5 absorption spectra measured with circularly polarized x-rays are fitted using multiplet calculations to obtain the effective magnetic moment. Arrott-Noakes plots, measured by the Dy M5 XMCD as a function of field at low temperatures, give a negative transition temperature. The evaporation of a ferromagnetic Co thin film did not introduce ferromagnetic ordering of the Dy dopants either; instead a lowering of the transition temperature was observed, pointing towards an antiferromagnetic ordering scenario. This result shows that there is a competition between the magnetic exchange interaction and the Zeeman interaction. The latter favors the Co and Dy magnetic moments to be both aligned along the direction of the applied magnetic field, while the exchange interaction is minimized if the Dy and Co atoms are antiferromagnetically coupled, as in zero applied field.

  19. The annealing temperature dependences of microstructures and magnetic properties in electro-chemical deposited CoNiFe thin films

    Science.gov (United States)

    Suharyadi, Edi; Riyanto, Agus; Abraha, Kamsul

    2016-04-01

    CoNiFe thin films with various compositions had been successfully fabricated using electro-chemical deposition method. The crystal structure of Co65Ni15Fe20, Co62Ni15Fe23, and Co55Ni15Fe30 thin films was fcc, bcc-fcc mix, and bcc, respectively. The difference crystal structure results the difference in magnetic properties. The saturation magnetic flux density (Bs) of Co65Ni15Fe20, Co62Ni15Fe23, and Co55Ni15Fe30 thin films was 1.89 T, 1.93 T, and 2.05 T, respectively. An optimal annealing temperature was determined for controlling the microstructure and magnetic properties of CoNiFe thin films. Depending on annealing temperature, the ratio of bcc and fcc structure varied without changing the film composition. By annealing at temperature of T ≥ 350°C, the intensity ratio of X-ray diffraction peaks for bcc(110) to fcc(111) increased. The increase of phase ratio of bcc(110) to fcc(111) caused the increase of Bs, from 1.89 T to 1.95 T. Coercivity (Hc) also increased after annealing, from 2.6 Oe to 18.6 Oe for fcc phase thin films, from 2.0 Oe to 12.0 Oe for fcc-bcc mix phase thin films, and 7.8 Oe to 8 Oe for bcc phase thin films. The changing crystal structures during annealing process indicated that the thermal treatment at high temperature cause the changing crystallinity and atomic displacement. The TEM bright-field images with corresponding selected-area electron diffraction (SAED) patterns showed that there are strongly effects of thermal annealing on the size of fcc and bcc phase crystalline grain as described by size of individual spot and discontinuous rings. The size of crystalline grains increased by thermal annealing. The evolution of bcc and fcc structures of CoNiFe during annealing is though to be responsible for the change of magnetic properties.

  20. Far-from-equilibrium growth of magnetic thin films with Blume-Capel impurities

    Science.gov (United States)

    Mazzitello, Karina I.; Candia, Julián; Albano, Ezequiel V.

    2015-04-01

    We investigate the irreversible growth of (2 +1 ) -dimensional magnetic thin films. The spin variable can adopt three states (si=±1 ,0 ), and the system is in contact with a thermal bath of temperature T . The deposition process depends on the change of the configuration energy, which, by analogy to the Blume-Capel Hamiltonian in equilibrium systems, depends on Ising-like couplings between neighboring spins (J ) and has a crystal field (D ) term that controls the density of nonmagnetic impurities (si=0 ). Once deposited, particles are not allowed to flip, diffuse, or detach. By means of extensive Monte Carlo simulations, we obtain the phase diagram in the crystal field vs temperature parameter space. We show clear evidence of the existence of a tricritical point located at Dt/J =1.145 (10 ) and kBTt/J =0.425 (10 ) , which separates a first-order transition curve at lower temperatures from a critical second-order transition curve at higher temperatures, in analogy with the previously studied equilibrium Blume-Capel model. Furthermore, we show that, along the second-order transition curve, the critical behavior of the irreversible growth model can be described by means of the critical exponents of the two-dimensional Ising model under equilibrium conditions. Therefore, our findings provide a link between well-known theoretical equilibrium models and nonequilibrium growth processes that are of great interest for many experimental applications, as well as a paradigmatic topic of study in current statistical physics.

  1. Novel magnetic indenter for rheological analysis of thin biological sheet for regenerative medicine

    Science.gov (United States)

    Kageshima, Masami; Maruyama, Toshiro; Akama, Tomoya; Nakamura, Tomoyuki

    2016-07-01

    A novel method is proposed for analyzing the mechanical properties of a thin sheet of cells or extracellular matrix cultured for regenerative medicine. A steel sphere is mounted onto the center of the sheet sample, placed over a circular aperture, and a loading force is exerted via an electromagnet with well-regulated current while the displacement of the sample center is optically detected. Details of the instrument and its performance are described. Loading and unloading experiment with stepwise magnetic force revealed that creep response of each of the cell sheet and matrix sheet can be expressed as a combination of a quasi-instantaneous deformation and two delayed elastic responses having different retardation times. The retardation time exhibited an increasing trend with the loading force. Close analysis of loading-force dependence and reversibility of the derived mechanical parameters revealed that these deformation modes are not independent but flexibly switches to each other depending on load magnitude and loading history. The cell sheet sample exhibited remarkable irreversibility between loading and unloading responses, which is attributed to response of the live cells to the sustained loading.

  2. Microstructure and magnetic properties of FeCo/Ti thin film multilayers annealed in nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Brunken, H., E-mail: hayo.brunken@rub.d [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, Universitaetsstrasse 150, 44801 Bochum (Germany); Somsen, C. [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, Universitaetsstrasse 150, 44801 Bochum (Germany); Research Department IS3/HTM, Ruhr-University Bochum, Universitaetsstrasse 150, 44801 Bochum (Germany); Savan, A. [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, Universitaetsstrasse 150, 44801 Bochum (Germany); Ludwig, A. [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, Universitaetsstrasse 150, 44801 Bochum (Germany); Research Department IS3/HTM, Ruhr-University Bochum, Universitaetsstrasse 150, 44801 Bochum (Germany)

    2010-11-01

    Multifunctional nanocomposites consisting of at least one ferromagnetic phase (e.g. FeCo) and one protective, wear resistant phase (e.g. TiN) are of interest for applications as sensors or actuators in harsh environments. This paper reports on the fabrication and characterization of nanocomposite thin films, prepared from FeCo/Ti metallic precursor multilayer composition spreads using a combinatorial sputter-deposition system. After deposition, the composition spread was annealed in nitrogen (5 x 10{sup 5} Pa pressure) at 850 {sup o}C for 1.5 h, leading to preferential nitriding of Ti to TiN, thus forming the protective phase. Automated energy dispersive X-ray analysis, Auger electron spectroscopy, X-ray diffraction measurements, transmission electron microscopy (TEM) and vibrating sample magnetometry were used for the characterization of the as deposited and nitrided composition spreads. As an unexpected result, the appearance of a Heusler phase (Co{sub 2}FeSi) in the nanocomposite was observed by TEM. After N{sub 2} annealing, the nanocomposites show reduced saturation magnetization values {mu}{sub 0}M{sub S} between 0.5 and 0.95 T and improved coercive field values {mu}{sub 0}H{sub c} between 4 and 13.8 mT, dependent on the TiN content.

  3. Structure and magnetic properties of Ni50Mn35In15 thin film

    Directory of Open Access Journals (Sweden)

    Chao Jing

    2015-04-01

    Full Text Available Thin film of Ni50Mn35In15 Heusler alloy was prepared on MgO(001 substrate by epitaxial growth in an ultra-high vacuum (UHV chamber by a Pulsed Laser Deposition (PLD method. The epitaxial growth process was monitored by in situ reflection high energy electron diffraction (RHEED and the structure of the film was checked by ex situ X-ray diffraction (XRD, which indicates that high quality Ni50Mn35In15 single crystal film with a face-centered-cubic (fcc structure could be stabilized on MgO(001. Magnetic property measurement was also conducted at various temperatures by using physical property measurement system (PPMS. A significant exchange bias was observed for Ni50Mn35In15 film, and the strength of the exchange bias field (HEB increases with the decrease of temperature. Such a behavior can be ascribed to the fact that the interfacial spin interaction between ferromagnetic (FM and antiferromagnetic (AFM cluster is enhanced with the decrease of temperature.

  4. Geometric and electronic structure of dysprosium thin films on tungsten surfaces Structural and magnetic properties

    CERN Document Server

    Moslemzadeh, N

    2001-01-01

    The rare earth thin films are frequently the focus of investigators due to their unusual structural and magnetic properties. Despite the potential interest of Dy/W systems to the surface/rare earth community, they have been little studied. This study is the first try of growing Dy on W(100) and W(112) and W(110) in which almost a complete set of information about film morphology and electronic structure of the surface and interface have been achieved. A set of different experiments have been done for this purpose including LEED, XPS, UPS (with synchrotron radiation) and STM. The growth modes of Dy on different W substrates (W(100), W(112) and W(110)) at RT and at elevated temperatures have been determined by XPS of Dy 3d sub 3 sub / sub 2 and W 4f intensities. Crystallographic ordering and the epitaxial relationship between adsorbate Dy and different W substrates have been studied with LEED and the effect of annealing temperature on the resultant superstructures was investigated. As a complementary study to t...

  5. Spatial evolution of multipeaked microwave magnetic envelope solitons in yttrium iron garnet thin films

    Science.gov (United States)

    Wu, Mingzhong; Kraemer, Michael A.; Scott, Mark M.; Patton, Carl E.; Kalinikos, Boris A.

    2004-08-01

    The spatial evolution of multi-peaked microwave magnetic envelope solitons in a thin yttrium iron garnet (YIG) film has been measured and analyzed. The experiments were done on a long and narrow 5-μm -thick single-crystal YIG film strip. Double-peaked and triple-peaked magnetostatic backward volume wave soliton pulses were excited at a nominal carrier frequency of 7.0GHz . The measurements utilized a movable inductive magnetodynamic probe detection system. The formation of these multi-peaked soliton (MPS) pulses is a two step process. First, an initial single large amplitude pulse gradually separates into two or more nonsolitonic peaks. After a certain propagation time, these nonsolitonic peaks evolve, in sequence, into solitonic peaks with constant phase (CP) and an overall stair-like profile. Typically, the larger amplitude peaks lead in time and become solitonic first. As the MPS signals propagate and decay, the peaks lose their CP character in reverse sequence. The region of existence for the “fully formed” MPS pulses for which all the individual peaks have CP character is extremely narrow, typically on the order of a few tenths of a millimeter. The velocities of the individual peaks scale linearly with the peak powers. A nonlinear response analysis of the peak velocity based on the method of envelopes gives a reasonable match to the data.

  6. Structure and magnetic properties of Ni50Mn35In15 thin film

    Institute of Scientific and Technical Information of China (English)

    Chao Jing; Liju Yu; Dong Zheng; Pan Liao; Yiming Cao; Jianhui Liang; Zhe Li; Baojuan Kang; Jincang Zhang

    2015-01-01

    Thin film of Ni50Mn35In15 Heusler alloy was prepared on MgO(001) substrate by epitaxial growth in an ultra-high vacuum (UHV) chamber by a Pulsed Laser Deposition (PLD) method. The epitaxial growth process was monitored by in situ reflection high energy electron diffraction (RHEED) and the structure of the film was checked by ex situ X-ray diffraction (XRD), which indicates that high quality Ni50Mn35In15 single crystal film with a face-centered-cubic (fcc) structure could be stabilized on MgO(001). Magnetic property measurement was also conducted at various temperatures by using physical property measurement system (PPMS). A significant exchange bias was observed for Ni50Mn35In15 film, and the strength of the exchange bias field (HEB ) increases with the decrease of temperature. Such a behavior can be ascribed to the fact that the interfacial spin interaction between ferromagnetic (FM) and antiferromagnetic (AFM) cluster is enhanced with the decrease of temperature.&2015 Chinese Materials Research Society. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

  7. Epitaxial LSMO thin films with correlation of electrical and magnetic properties above 400 K

    Energy Technology Data Exchange (ETDEWEB)

    Štrbík, V., E-mail: vladimir.strbik@savba.sk [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 84104 Bratislava (Slovakia); Reiffers, M. [Faculty of Humanities and Natural Sciences, University of Prešov, Ul. 17. novembra 1, 081 16 Prešov (Slovakia); Dobročka, E.; Šoltýs, J.; Španková, M.; Chromik, Š. [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 84104 Bratislava (Slovakia)

    2014-09-01

    Highlights: • Metal–insulator transition temperature above 400 K. • Correlation of ferromagnetic transition temperature with temperature of metal–insulator transition. • Correlation of ferromagnetic and metallic properties at temperatures below 400 K. • Epitaxial growth of LSMO film on MgO substrate. - Abstract: We have prepared La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) thin films of 100 nm thickness with enhanced temperature of metal–insulator transition T{sub MI} ≥ 400 K on MgO (0 0 1) substrates. The X-ray diffraction measurements (θ–2θ scan, ω-scan and ϕ-scan) show a c-axis oriented in-plane heteroepitaxial growth of the LSMO on the MgO. Sensitive magnetic measurements of the LSMO susceptibility confirm the correlation of metal–insulator and ferromagnetic–paramagnetic transitions at temperature of T{sub MI} = 406 K and so the coincidence with double exchange theory.

  8. Structural and magnetic analysis of Cu, Co substituted NiFe{sub 2}O{sub 4} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Hakikat; Bala, Kanchan; Negi, N. S. [Department of physics Himachal Pradesh University Shimla (H.P.) India (India)

    2016-05-23

    In the present work we prepared NiFe{sub 2}O{sub 4}, Ni{sub 0.95}Cu{sub 0.05}Fe{sub 2}O{sub 4} and Ni{sub 0.94}Cu{sub 0.05}Co{sub 0.01} Fe{sub 2}O{sub 4} thin films by metallo-organic decomposition method (MOD) using spin coating technique. The thin films were analyzed by X-ray diffractometer (XRD) and Atomic force microscope (AFM) for structural studies. The XRD patterns confirmed the ferrite phase of thin films. From AFM, we analyzed surface morphology, calculated grain size (GS) and root mean square roughness (RMSR). Room temperature magnetic properties were investigated by vibrating sample magnetometer (VSM).

  9. Large magnetization and high Curie temperature in highly disordered nanoscale Fe2CrAl thin films

    Science.gov (United States)

    Dulal, Rajendra P.; Dahal, Bishnu R.; Forbes, Andrew; Pegg, Ian L.; Philip, John

    2017-02-01

    We have successfully grown nanoscale Fe2CrAl thin films on polished Si/SiO2 substrates using an ultra-high vacuum deposition with a base pressure of 9×10-10 Torr. The thickness of thin films ranges from 30 to 100 nm. These films exhibit cubic crystal structure with lattice disorder and display ferromagnetic behavior. The Curie temperature is greater than 400 K, which is much higher than that reported for bulk Fe2CrAl. The magnetic moments of the films varies from 2.5 to 2.8 μB per formula unit, which is larger than the reported bulk values. Thus, the disordered nanoscale Fe2CrAl films exhibit strong Fe-Fe exchange interactions through Fe-Cr-Fe and Fe-Al-Fe layers, resulting in both a large magnetization and a high Curie temperature.

  10. Static and high frequency magnetic properties of FeGa thin films deposited on convex flexible substrates

    Science.gov (United States)

    Yu, Ying; Zhan, Qingfeng; Wei, Jinwu; Wang, Jianbo; Dai, Guohong; Zuo, Zhenghu; Zhang, Xiaoshan; Liu, Yiwei; Yang, Huali; Zhang, Yao; Xie, Shuhong; Wang, Baomin; Li, Run-Wei

    2015-04-01

    Magnetostrictive FeGa thin films were deposited on the bowed flexible polyethylene terephthalate (PET) substrates, which were fixed on the convex mold. A compressive stress was induced in FeGa films when the PET substrates were shaped from convex to flat. Due to the effect of magnetostriction, FeGa films exhibit an obvious in-plane uniaxial magnetic anisotropy which could be enhanced by increasing the applied pre-strains on the substrates during growth. Consequently, the ferromagnetic resonance frequency of the films was significantly increased, but the corresponding initial permeability was decreased. Moreover, the films with pre-strains less than 0.78% exhibit a working bandwidth of microwave absorption about 2 GHz. Our investigations demonstrated a convenient method via the pre-strained substrates to tune the high frequency properties of magnetic thin films which could be applied in flexible microwave devices.

  11. Static and high frequency magnetic properties of FeGa thin films deposited on convex flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ying [Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, School of Materials Science and Engineering, Xiangtan University, Xiangtan, Hunan 411105 (China); Zhan, Qingfeng, E-mail: zhanqf@nimte.ac.cn, E-mail: runweili@nimte.ac.cn; Dai, Guohong; Zuo, Zhenghu; Zhang, Xiaoshan; Liu, Yiwei; Yang, Huali; Zhang, Yao; Wang, Baomin; Li, Run-Wei, E-mail: zhanqf@nimte.ac.cn, E-mail: runweili@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wei, Jinwu; Wang, Jianbo [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Xie, Shuhong [Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, School of Materials Science and Engineering, Xiangtan University, Xiangtan, Hunan 411105 (China)

    2015-04-20

    Magnetostrictive FeGa thin films were deposited on the bowed flexible polyethylene terephthalate (PET) substrates, which were fixed on the convex mold. A compressive stress was induced in FeGa films when the PET substrates were shaped from convex to flat. Due to the effect of magnetostriction, FeGa films exhibit an obvious in-plane uniaxial magnetic anisotropy which could be enhanced by increasing the applied pre-strains on the substrates during growth. Consequently, the ferromagnetic resonance frequency of the films was significantly increased, but the corresponding initial permeability was decreased. Moreover, the films with pre-strains less than 0.78% exhibit a working bandwidth of microwave absorption about 2 GHz. Our investigations demonstrated a convenient method via the pre-strained substrates to tune the high frequency properties of magnetic thin films which could be applied in flexible microwave devices.

  12. Structure and magnetic properties of hcp and fcc nanocrystalline thin Ni films and nanoparticles produced by radio frequency magnetron sputtering.

    Science.gov (United States)

    Kapaklis, Vassilios; Pappas, Spiridon D; Poulopoulos, Panagiotis; Trachylis, Dimitrios; Schweiss, Peter; Politis, Constantin

    2010-09-01

    We report on the growth of thin Ni films by radio frequency magnetron sputtering in Ar-plasma. The growth temperature was about 350 K and the films were deposited on various substrates such as glass, silicon, sapphire and alumina. The thickness of the thinnest films was estimated by the appearance of Kiessig fringes up to about 2theta = 8 degrees in the small-angle X-ray diffraction pattern, as expected for high-quality atomically-flat thin films. With the help of this, a quartz balance system was calibrated and used for measuring the thickness of thicker samples with an accuracy of better than 5%. Structural characterization via X-ray diffraction and high resolution transmission electron microscopy revealed an Ar-gas pressure window, where single phase hcp Ni films may be grown. The magnetic response of the Ni films was checked at room temperature via a newly established and fully automatic polar magneto-optic Kerr effect magnetometer. The hcp films show no magnetic response. Interestingly, the magnetic saturation field of fcc films deposited at low Ar pressure is comparable to the one of bulk Ni, while the one of fcc films deposited at high Ar pressures is decreased, revealing the presence of residual strain in the films. Finally, it is shown that it is possible to form films which contain magnetic Ni fcc nanoparticles in a non-magnetic hcp matrix, i.e., a system interesting for technological applications demanding a single Ni target for its production.

  13. Comparison of the magnetic properties of GeMn thin films through Mn L-edge x-ray absorption

    Energy Technology Data Exchange (ETDEWEB)

    Ahlers, S.; Stone, P.R.; Sircar, N.; Arenholz, E.; Dubon, O. D.; Bougeard, D.

    2009-08-04

    X-ray absorption spectroscopy of epitaxial GeMn thin films reveals an experimentally indistinguishable electronic configuration of Mn atoms incorporated in Ge{sub 1?x}Mn{sub x} nanoclusters and in precipitates of the intermetallic compound Mn{sub 5}Ge{sub 3}, respectively. However, the average magnetic response of thin films containing Ge{sub 1?x}Mn{sub x} nanoclusters is lower than the response of films containing Mn{sub 5}Ge{sub 3} precipitates. This reduced magnetic response of Ge{sub 1?x}Mn{sub x} nanoclusters is explained in terms of a fraction of Mn atoms being magnetically inactive due to antiferromagnetic coupling or the presence of structural disorder. A determination of the role of magnetically inactive Mn atoms in the self-assembly of the thermodynamically metastable Ge{sub 1?x}Mn{sub x} nanoclusters seems to be an essential ingredient for an enhanced control of this promising high Curie temperature magnetic semiconductor.

  14. Boundary magnetization properties of epitaxial C r2 -xA lxO3 thin films

    Science.gov (United States)

    Fallarino, Lorenzo; Binek, Christian; Berger, Andreas

    2015-06-01

    The magnetoelectric antiferromagnet α -C r2O3 (chromia) is known to possess a roughness insensitive net equilibrium magnetization at the (0001) surface, called boundary magnetization (BM), which is coupled to the bulk antiferromagnetic order parameter. In order to verify whether this symmetry sensitive BM persists in alloys, we investigate the impact of diamagnetic dilution on chromia thin films alloyed with the isostructural α -A l2O3 (alumina). Single-crystalline C r2 -xA lxO3 thin films with (0001) surface orientation and varying stoichiometry have been grown by sputter codeposition in the concentration range between x =0 and x =0.6 . For these samples, we find the corundum crystal structure, the antiferromagnetic ordering, and the boundary magnetization to be preserved. We also find that the critical temperature TN can be tuned by alloying with α -A l2O3 , using the BM as a probe to study the magnetic phase transition. Furthermore, we were able to evaluate the critical exponent and the absolute BM values for different samples. Both properties corroborate that the observed magnetic signals originate from the BM rather than the bulk of the samples.

  15. Surface structure effect on the magnetic anisotropy of Co/Pd (001) thin film: A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Je, Minyeong [Department of Materials Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Choi, Heechae [Computational Science Research Center, Korea Institute of Science and Technology, 14-Gil 5, Hwarang-Ro, Seoungbuk-Gu, Seoul (Korea, Republic of); Hwang, Yubin; Yun, Kyung-Han [Department of Materials Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Chung, Yong-Chae, E-mail: yongchae@hanyang.ac.kr [Department of Materials Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2015-08-31

    Perpendicular magnetic anisotropy (PMA) in thin film is the key factor to obtain good properties for high density storage devices. Although the importance of the properties of PMA is well-known for Co/Pd thin film, it is still unclear which surface structure and composition indicate that PMA is present. In this work, the surface structure and magnetic properties of L1{sub 0}-ordered Co/Pd (001) were analyzed using density functional theory calculations. It was confirmed that only Pd-rich A among the facile surface structures indicates PMA properties. However, according to the calculated surface energy, not only Pd-rich A but also Co-rich B is among the most energetically stable structures. The density of states showed a clear distinct electronic structure between Pd-rich A and Co-rich B derived from the structural difference. This result indicates that PMA is not always present in a sandwich structure such as Pd-rich A. The results provide a useful guide to magnetic devices created using L1{sub 0}-ordered Co/Pd (001) on substrate Pd. - Highlights: • Investigation on the possible surface structure of L1{sub 0}-ordered Co/Pd (001) • Using surface phase diagram, the stable structures were Pd-rich A and Co-rich B. • The magnetic property of Pd-rich A and Co-rich B has been measured and discussed. • Pd-rich A only showed perpendicular magnetic anisotropy.

  16. Magnetic transition anisotropies in orthorhombic LuMnO3 and HoMnO3 multiferroic thin films

    Science.gov (United States)

    Tsai, T. Y.; Lin, T. H.; Slowry, S.; Luo, C. W.; Wu, K. H.; Lin, J.-Y.; Uen, T. M.; Juang, J. Y.

    2010-01-01

    We have successfully prepared the b-axis-oriented orthorhombic LuMnO3 (LuMO) and HoMnO3 (HMO) thin films by pulsed laser deposition on (110)-LaAlO3 substrates. The nearly perfect alignment between the film growth orientation and the substrate allows us to study the magnetic transitions along the respective crystal orientation, which has displayed marked anisotropic behaviours. In particular, with the largest ionic size difference between Lu and Ho for the family of RMnO3 displaying the E-type AFM, the effects of lattice distortion on the magnetic transition are compared.

  17. Structural control of magnetic anisotropy in a strain-driven multiferroic EuTiO3 thin film

    Science.gov (United States)

    Ke, X.; Birol, T.; Misra, R.; Lee, J.-H.; Kirby, B. J.; Schlom, D. G.; Fennie, C. J.; Freeland, J. W.

    2013-09-01

    Octahedral distortion plays a key role in engineering the physical properties of heterostructures composed of perovskite oxides. We observe a strong in-plane uniaxial magnetic anisotropy in a strain-enabled multiferroic EuTiO3 thin film epitaxially grown on a (110)o DyScO3 substrate. First-principles calculations show that the magnetic anisotropy is closely correlated with the uniaxial TiO6 octahedral tilting and the ferroelectric polarization of the film, indicating potential strong magnetoelectric coupling in the strain-engineered multiferroic system.

  18. Trapped Field Characteristics of Stacked YBCO Thin Plates for Compact NMR Magnets: Spatial Field Distribution and Temporal Stability.

    Science.gov (United States)

    Hahn, Seungyong; Kim, Seok Beom; Ahn, Min Cheol; Voccio, John; Bascuñán, Juan; Iwasa, Yukikazu

    2010-06-01

    This paper presents experimental and analytical results of trapped field characteristics of a stack of square YBCO thin film plates for compact NMR magnets. Each YBCO plate, 40 mm × 40 mm × 0.08 mm, has a 25-mm diameter hole at its center. A total of 500 stacked plates were used to build a 40-mm long magnet. Its trapped field, in a bath of liquid nitrogen, was measured for spatial field distribution and temporal stability. Comparison of measured and analytical results is presented: the effects on trapped field characteristics of the unsaturated nickel substrate and the non-uniform current distribution in the YBCO plate are discussed.

  19. Full-Heusler Co2FeSi alloy thin films with perpendicular magnetic anisotropy inducedby MgO-interfaces

    OpenAIRE

    高村, 陽太; Takamura, Yota; 鈴木, 隆寛; Suzuki, Takahiro; 藤野, 頼信; Fujino, Yorinobu; 中川, 茂樹; Nakagawa, Shigeki

    2014-01-01

    A 100-nm-thick L21-ordered full-Heusler Co2FeSi (CFS) alloy film was fabricated using the facing targets sputtering (FTS) method at a substrate temperature TS of 300 ºC. The degrees of L21- and B2-order for the film were 37% and 96%, respectively. In addition, full-Heusler CFS alloy thin films with perpendicular magnetic anisotropy (PMA) induced by the magnetic anisotropy of MgO-interfaces were also successfully fabricated using the FTS method. The CFS/MgO stacked layers exhibited PMA when th...

  20. Composition dependence of magnetic and magnetotransport properties in C60-Co granular thin films

    Science.gov (United States)

    Sugai, Isamu; Sakai, Seiji; Matsumoto, Yoshihiro; Naramoto, Hiroshi; Mitani, Seiji; Takanashi, Koki; Maeda, Yoshihito

    2010-09-01

    Composition dependence of magnetic and magnetotransport properties in C60Cox thin films exhibiting large magnetoresistance (MR) effect was investigated in the Co composition range of x =8-20, where x denotes the number of Co atoms per C60 molecule. From the superparamagnetic magnetization curves observed, the average diameter (dave) of Co nanoparticles dispersed in the matrix phase was evaluated to be approximately 1 nm for the sample of x =8, and increased with the Co composition, x. By analyzing the temperature (T) dependence of resistivity based on the model by Abeles et al. [Adv. Phys. 24, 407 (1975)], the average charging energies (⟨ÊC⟩) of Co nanoparticles were evaluated to be 2-9 meV for the samples of x =8-17 while the considerably weak temperature dependence suggested much smaller values of ⟨ÊC⟩ for the samples of x >17. The composition dependence of dave and ⟨ÊC⟩ revealed a structural transition from well-defined granular structures in the range of x =8-17 to magnetically and electronically coupled states of Co nanoparticles over x ˜17. As a result of the structural change, the MR behavior became different between the two composition regions separated at x ˜17. In particular, for the samples of x =8-17, the bias-voltage (V) dependence of the MR ratio in the low-V region fits well with an unusual exponential form of MR=MR0 exp(-V/Vc) at T proportion to ⟨ÊC⟩ and also that the fitting parameter Vc is closely correlated with ⟨ÊC⟩. These results indicate that the charging effect of Co nanoparticles plays an important role in the anomalously large MR effect of C60-Co granular films. In addition, the power-law dependence of MR on T (MR∝T-α,α˜2) was also observed at relatively high temperature range T ≥10 K in the wide range of the composition.

  1. Study on TCT split-flow for HPV positive method on Xinjiang cervical cancer screening%careHPV 初筛及 TCT 分流法在新疆宫颈癌筛查中的应用

    Institute of Scientific and Technical Information of China (English)

    帕提曼·米吉提; 唐努尔·阿布力米提; 古扎丽努尔·阿不力孜; 李华

    2015-01-01

    Objective To evaluate the clinical value of TCT split-flow for HPV positive method on Xinjiang cervical cancer screening project.Methods Colposcopy and cervical biopsy were given to the women with positive result of the careHPV test and Thinprep test.Diagnostic evaluation was conducted to detect the sensitivity,specificity,predictive positive value and predictive negative value and the AUC.Diagnostic val-ue was compared by ROC curve and analyzed by SPSS19.0 software.Results It showed better value for the test of TCT split-flow for HPV positive result than HPV split-flow for TCT positive method,with their AUC 0.743 and 0.680 respectively.Conclusions Split-flow by TCT after screening by careHPV method showed high diagnostic value in Xinjiang cervical cancer screening.%果以careHPV 为初筛、薄层液基细胞学为分流的筛查方法 AUC 值为0.743,高于以细胞学初筛、HPV 分流法。结论careHPV 初筛、细胞学分流法在新疆农村地区妇女宫颈癌筛查中有较好的应用前景。

  2. Magnetic, ferroelectric and leakage current properties of gadolinium doped bismuth ferrite thin films by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hone-Zern, E-mail: hzc@hust.edu.tw [Department of Electronic Engineering, Hsiuping University of Science and Technology, Taichung, Taiwan (China); Kao, Ming-Cheng, E-mail: kmc@hust.edu.tw [Department of Electronic Engineering, Hsiuping University of Science and Technology, Taichung, Taiwan (China); Young, San-Lin [Department of Electronic Engineering, Hsiuping University of Science and Technology, Taichung, Taiwan (China); Hwang, Jun-Dar [Department of Electrophysics, National Chiayi University, Chiayi, Taiwan (China); Chiang, Jung-Lung [Department of Mobile Technology, Toko University, Chiayi, Taiwan (China); Chen, Po-Yen [Department of Electronic Engineering, Hsiuping University of Science and Technology, Taichung, Taiwan (China)

    2015-05-01

    Bi{sub 0.9}Gd{sub 0.1}FeO{sub 3} (BGFO) thin films were fabricated on Pt(111)/Ti/SiO{sub 2}/Si(100) substrates by using the sol–gel technology. The effects of annealing temperature (400–700 °C) on microstructure and multiferroic properties of thin films were investigated. The X-ray diffraction analysis showed that the BGFO thin films had an orthorhombic structure. The thin films showed ferroelectric and ferromagnetic properties with remanent polarization (2P{sub r}) of 10 μC/cm{sup 2}, remnant magnetization (2M{sub r}) of 2.4 emu/g and saturation magnetization (M{sub s}) of 5.3 emu/g. A small leakage current density (J) was 4.64×10{sup −8} A/cm{sup 2} under applied field 100 kV/cm. It was found that more than one conduction mechanism is involved in the electric field range used in these experiments. The leakage current mechanisms were controlled by Poole–Frenkel emission in the low electric field region and by Schottky emission from the Pt electrode in the high field region. - Highlights: • Bi{sub 3.96}Pr{sub 0.04}Ti{sub 2.95}Nb{sub 0.05}O{sub 12} thin films were prepared by sol–gel technology. • Thin films showed 2P{sub r} of 10 μC/cm{sup 2}, 2M{sub r} of 2.4 emu/g and M{sub s} of 5.3 emu/g. • Leakage current mechanisms were controlled by Poole–Frenkel and Schottky emission.

  3. Stress induced magnetic anisotropy of CoFe2O4 thin films using pulsed laser deposition

    NARCIS (Netherlands)

    Pham Duc Thang, P.D.T.; Rijnders, Augustinus J.H.M.; Blank, David H.A.

    2007-01-01

    Cobalt ferrite (CoFe2O4) thin films (E70 nm) were epitaxially grown on TiO2-terminated (0 0 1) SrTiO3 substrates by pulsed laser deposition (PLD). Films with very smooth surface, which follow the terrace of the substrate, were obtained at temperatures below 600 1C. The magnetic properties of CoFe2O4

  4. Development of a passive and remote magnetic microsensor with thin-film giant magnetoimpedance element and surface acoustic wave transponder

    KAUST Repository

    Al Rowais, Hommood

    2011-01-01

    This paper presents the development of a wireless magnetic field sensor consisting of a three-layer thin-film giant magnetoimpedance sensor and a surface acoustic wave device on one substrate. The goal of this integration is a passive and remotely interrogated sensor that can be easily mass fabricated using standard microfabrication tools. The design parameters, fabrication process, and a model of the integrated sensor are presented together with experimental results of the sensor. © 2011 American Institute of Physics.

  5. Thin Co/Ni-based bottom pinned spin-transfer torque magnetic random access memory stacks with high annealing tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Tomczak, Y., E-mail: Yoann.Tomczak@imec.be [IMEC Kapeldreef 75, B-3001 Leuven (Belgium); Department of Chemistry, KU Leuven (University of Leuven), Celestijnenlaan 200F, B-3001 Leuven (Belgium); Swerts, J.; Mertens, S.; Lin, T.; Couet, S.; Sankaran, K.; Pourtois, G.; Kim, W.; Souriau, L.; Van Elshocht, S.; Kar, G.; Furnemont, A. [IMEC Kapeldreef 75, B-3001 Leuven (Belgium); Liu, E. [Department of Chemistry, KU Leuven (University of Leuven), Celestijnenlaan 200F, B-3001 Leuven (Belgium)

    2016-01-25

    Spin-transfer torque magnetic random access memory (STT-MRAM) is considered as a replacement for next generation embedded and stand-alone memory applications. One of the main challenges in the STT-MRAM stack development is the compatibility of the stack with CMOS process flows in which thermal budgets up to 400 °C are applied. In this letter, we report on a perpendicularly magnetized MgO-based tunnel junction (p-MTJ) on a thin Co/Ni perpendicular synthetic antiferromagnetic layer with high annealing tolerance. Tunnel magneto resistance (TMR) loss after annealing occurs when the reference layer loses its perpendicular magnetic anisotropy due to reduction of the CoFeB/MgO interfacial anisotropy. A stable Co/Ni based p-MTJ stack with TMR values of 130% at resistance-area products of 9 Ω μm{sup 2} after 400 °C anneal is achieved via moment control of the Co/Ta/CoFeB reference layer. Thinning of the CoFeB polarizing layer down to 0.8 nm is the key enabler to achieve 400 °C compatibility with limited TMR loss. Thinning the Co below 0.6 nm leads to a loss of the antiferromagnetic interlayer exchange coupling strength through Ru. Insight into the thickness and moment engineering of the reference layer is displayed to obtain the best magnetic properties and high thermal stability for thin Co/Ni SAF-based STT-MRAM stacks.

  6. Structure and magnetic properties of Fe doped In{sub 2}O{sub 3} thin films prepared by electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, N. Sai; Kaleemulla, S., E-mail: skaleemulla@gmail.com; Rao, N. Madhusudhana; Krishnamoorthi, C.; Begam, M. Rigana [Thin Films Laboratory, School of Advanced Sciences, VIT University, Vellore – 632014 (India); Amarendra, G. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); UGC-DAE-CSR, Kalpakkam Node, Kokilamedu, Tamilnadu -603104 (India)

    2015-06-24

    Pure and Fe (7 at.%) doped In{sub 2}O{sub 3} thin films were grown onto the glass substrates by electron beam evaporation technique. The structural and magnetic properties of the pure and Fe doped In{sub 2}O{sub 3} thin films have been studied. The undoped and Fe doped In{sub 2}O{sub 3} thin films shown ferromagnetic property at room temperature. A magnetization of 24 emu/cm{sup 3} was observed for pure In{sub 2}O{sub 3} thin films. The magnetization of 38.23 emu/cm{sup 3} was observed for the Fe (7 at.%) doped In{sub 2}O{sub 3} thin films.

  7. Magnetic, ferroelectric and leakage current properties of gadolinium doped bismuth ferrite thin films by sol-gel method

    Science.gov (United States)

    Chen, Hone-Zern; Kao, Ming-Cheng; Young, San-Lin; Hwang, Jun-Dar; Chiang, Jung-Lung; Chen, Po-Yen

    2015-05-01

    Bi0.9Gd0.1FeO3 (BGFO) thin films were fabricated on Pt(111)/Ti/SiO2/Si(100) substrates by using the sol-gel technology. The effects of annealing temperature (400-700 °C) on microstructure and multiferroic properties of thin films were investigated. The X-ray diffraction analysis showed that the BGFO thin films had an orthorhombic structure. The thin films showed ferroelectric and ferromagnetic properties with remanent polarization (2Pr) of 10 μC/cm2, remnant magnetization (2Mr) of 2.4 emu/g and saturation magnetization (Ms) of 5.3 emu/g. A small leakage current density (J) was 4.64×10-8 A/cm2 under applied field 100 kV/cm. It was found that more than one conduction mechanism is involved in the electric field range used in these experiments. The leakage current mechanisms were controlled by Poole-Frenkel emission in the low electric field region and by Schottky emission from the Pt electrode in the high field region.

  8. Silicon nitride gradient film as the underlayer of ultra-thin tetrahedral amorphous carbon overcoat for magnetic recording slider

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guigen, E-mail: wanggghit@yahoo.com [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Kuang Xuping; Zhang Huayu; Zhu Can [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Han Jiecai [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Zuo Hongbo [Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Ma Hongtao [SAE Technologies Development (Dongguan) Co., Ltd., Dongguan 523087 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer The ultra-thin carbon films with different silicon nitride (Si-N) film underlayers were prepared. Black-Right-Pointing-Pointer It highlighted the influences of Si-N underlayers. Black-Right-Pointing-Pointer The carbon films with Si-N underlayers obtained by nitriding especially at the substrate bias of -150 V, can exhibit better corrosion protection properties - Abstract: There are higher technical requirements for protection overcoat of magnetic recording slider used in high-density storage fields for the future. In this study, silicon nitride (Si-N) composition-gradient films were firstly prepared by nitriding of silicon thin films pre-sputtered on silicon wafers and magnetic recording sliders, using microwave electron cyclotron resonance plasma source. The ultra-thin tetrahedral amorphous carbon films were then deposited on the Si-N films by filtered cathodic vacuum arc method. Compared with amorphous carbon overcoats with conventional silicon underlayers, the overcoats with Si-N underlayers obtained by plasma nitriding especially at the substrate bias of -150 V, can provide better corrosion protection for high-density magnetic recording sliders.

  9. The Influence of Doping with Transition Metal Ions on the Structure and Magnetic Properties of Zinc Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Jenica Neamtu

    2014-01-01

    Full Text Available Zn1−xNixO (x=0.03÷0.10 and Zn1−xFexO (x=0.03÷0.15 thin films were synthesized by sol-gel method. The structure and the surface morphology of zinc oxide thin films doped with transition metal (TM ions have been investigated by X-ray diffraction (XRD and atomic force microscopy (AFM. The magnetic studies were done using vibrating sample magnetometer (VSM at room temperature. Experimental results revealed that the substitution of Ni ions in ZnO wurtzite lattice for the contents x=0.03÷0.10 (Ni2+ leads to weak ferromagnetism of thin films. For Zn1-xFexO with x=0.03÷0.05, the Fe3+ ions are magnetic coupling by superexchange interaction via oxygen ions in wurtzite structure. For x=0.10÷0.15 (Fe3+ one can observe the increasing of secondary phase of ZnFe2O4 spinel. The Zn0.9Fe0.1O film shows a superparamagnetic behavior due to small crystallite sizes and the net spin magnetic moments arisen from the interaction between the iron ions through an oxygen ion in the spinel structure.

  10. Effects of additive elements (Cu, Zr, Al) on morphological and magnetic properties of NdFeB thin films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.G. [Research Institute of Magnetic Materials, Lanzhou University, Lanzhou 730000 (China); Li, R.S. [Research Institute of Magnetic Materials, Lanzhou University, Lanzhou 730000 (China); Yang, Z. [Research Institute of Magnetic Materials, Lanzhou University, Lanzhou 730000 (China)]. E-mail: yangz@lzu.edu.cn; Matsumoto, M. [Department of Information Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Morisako, A. [Department of Information Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Takei, S. [Department of Information Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan)

    2005-03-25

    Cu, Zr, Al were doped into the NdFeB thin films to improve the morphological and magnetic properties of the films. Distinct results have been observed due to the different nature of these additives (such as atomic radius and chemical affinity, etc.). The morphological and magnetic properties of the films could be improved selectively according to the additive element. Grains in the Cu-doped film significantly grew and became strip-like. Both Zr and Al addition effectively reduced the grain size. But Zr addition led to a large grain size distribution while Al addition produced more uniformly sized grains in the film. The perpendicular coercivities of NdFeB films could be enhanced by doping a certain amount of the additive element. Addition of 1.0 at.% Cu or 3.8 at.% Zr increased the perpendicular coercivity H {sub cperpendicular} up to 487 or 565 kA/m from 382 kA/m, respectively. On the other hand, addition of 5.0 at.% Al could effectively moderate H {sub cperpendicular} to 279 kA/m while remained a high perpendicular remanent magnetization ratio S{sub perpendicular} around 0.9. Magnetization reversal mechanisms of the doped samples were also discussed according to the angular dependence of the coercivity H {sub c}({theta}) and M-H loop shapes. It was suggested that magnetization reversal of Cu-doped sample was initiated by domain wall motion and ended by domain wall pinning. Most of the grains in the Zr-doped sample were inversely magnetized by magnetization coherent rotation, but the rest were demagnetized by magnetization incoherent switching. In the Al-doped sample, magnetization reversal was proceeded mainly by magnetization incoherent rotation.

  11. Mean-field and high temperature series expansion calculations of some magnetic properties of Ising and XY antiferromagnetic thin-films

    Institute of Scientific and Technical Information of China (English)

    R. Masrour; M. Hamedoun; A. Benyoussef

    2012-01-01

    In this work,the magnetic properties of Ising and XY antiferromagnetic thin-films are investigated each as a function of Néel temperature and thickness for layers (n =2,3,4,5,6,and bulk (oo)) by means of a mean-field and high temperature series expansion (HTSE) combined with Padé approximant calculations.The scaling law of magnetic susceptibility and magnetization is used to determine the critical exponent % veff (mean),ratio of the critical exponents γ/v,and magnetic properties of Ising and XY antiferromagnetic thin-films for different thickness layers n =2,3,4,5,6,and bulk (∞).

  12. Giant perpendicular magnetic anisotropy energies in CoPt thin films: impact of reduced dimensionality and imperfections.

    Science.gov (United States)

    Brahimi, Samy; Bouzar, Hamid; Lounis, Samir

    2016-12-14

    The impact of reduced dimensionality on the magnetic properties of the tetragonal L1 0 CoPt alloy is investigated from ab initio considering several kinds of surface defects. By exploring the dependence of the magnetocrystalline anisotropy energy (MAE) on the thickness of CoPt thin films, we demonstrate the crucial role of the chemical nature of the surface. For instance, Pt-terminated thin films exhibit huge MAEs which can be 1000% larger than those of Co-terminated films. Besides the perfect thin films, we scrutinize the effect of defective surfaces such as stacking faults or anti-sites on the surface layers. Both types of defects reduce considerably the MAE with respect to the one obtained for Pt-terminated thin films. A detailed analysis of the electronic structure of the thin films is provided with a careful comparison to the CoPt bulk case. The behavior of the MAEs is then related to the location of the different virtual bound states utilizing second order perturbation theory.

  13. Effect of Low-Frequency Alternative-Current Magnetic Susceptibility in Ni80Fe20 Thin Films

    Directory of Open Access Journals (Sweden)

    Yuan-Tsung Chen

    2012-01-01

    Full Text Available X-ray diffraction (XRD results indicate that the NiFe thin films had a face-centered cubic (FCC structure. Post-annealing treatment increased the crystallinity of NiFe films over those at room temperature (RT, suggesting that NiFe crystallization yields FCC (111 texturing. Post-annealing treatments increase crystallinity over that obtained at RT. This paper focuses on the maximum alternative-current magnetic susceptibility (χac value of NiFe thin films with resonance frequency (fres at low frequencies from 10 Hz to 25000 Hz. These results demonstrate that the χac of NiFe thin films increased with post-annealing treatment and increasing thickness. The NiFe (111 texture suggests that the relationship between magneto-crystalline anisotropy and the maximum χac value with optimal resonance frequency (fres increased spin sensitivity at optimal fres. The results obtained under the three conditions revealed that the maximum χac value and optimal fres of a 1000 Å-thick NiFe thin film are 3.45 Hz and 500 Hz, respectively, following postannealing at TA=250°C for 1 h. This suggests that a 1000 Å NiFe thin film post-annealed at TA=250°C is suitable for gauge sensor and transformer applications at low frequencies.

  14. Giant perpendicular magnetic anisotropy energies in CoPt thin films: impact of reduced dimensionality and imperfections

    Science.gov (United States)

    Brahimi, Samy; Bouzar, Hamid; Lounis, Samir

    2016-12-01

    The impact of reduced dimensionality on the magnetic properties of the tetragonal L1 0 CoPt alloy is investigated from ab initio considering several kinds of surface defects. By exploring the dependence of the magnetocrystalline anisotropy energy (MAE) on the thickness of CoPt thin films, we demonstrate the crucial role of the chemical nature of the surface. For instance, Pt-terminated thin films exhibit huge MAEs which can be 1000% larger than those of Co-terminated films. Besides the perfect thin films, we scrutinize the effect of defective surfaces such as stacking faults or anti-sites on the surface layers. Both types of defects reduce considerably the MAE with respect to the one obtained for Pt-terminated thin films. A detailed analysis of the electronic structure of the thin films is provided with a careful comparison to the CoPt bulk case. The behavior of the MAEs is then related to the location of the different virtual bound states utilizing second order perturbation theory.

  15. Domain size criterion for the observation of all-optical helicity-dependent switching in magnetic thin films

    Science.gov (United States)

    El Hadri, Mohammed Salah; Hehn, Michel; Pirro, Philipp; Lambert, Charles-Henri; Malinowski, Grégory; Fullerton, Eric E.; Mangin, Stéphane

    2016-08-01

    To understand the necessary condition for the observation of all-optical helicity-dependent switching (AO-HDS) of magnetization in thin films, we investigated ferromagnetic Co/Pt and Co/Ni multilayers as well as ferrimagnetic TbCo alloys as a function of magnetic layer compositions and thicknesses. We show that both ferro- and ferrimagnets with high saturation magnetization show AO-HDS if their magnetic thickness is strongly reduced below a material-dependent threshold thickness. By taking into account the demagnetizing energy and the domain wall energy, we are able to define a criterion to predict whether AO-HDS or thermal demagnetization (TD) will be observed. This criterion for the observation of AO-HDS is that the equilibrium size of magnetic domains forming during the cooling process should be larger than the laser spot size. From these results we anticipate that more magnetic materials are expected to show AO-HDS. However, the effect of the optical pulses' helicity is hidden by the formation of small magnetic domains during the cooling process.

  16. Thin yttrium iron garnet films grown by pulsed laser deposition: Crystal structure, static, and dynamic magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, N. S., E-mail: nsokolov@fl.ioffe.ru; Fedorov, V. V.; Korovin, A. M.; Suturin, S. M.; Baranov, D. A.; Gastev, S. V.; Krichevtsov, B. B.; Bursian, V. E.; Lutsev, L. V. [Ioffe Physical-Technical Institute of Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Maksimova, K. Yu.; Grunin, A. I. [Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation); Tabuchi, M. [Synchrotron Radiation Research Center, Nagoya University, Nagoya 464-8603 (Japan)

    2016-01-14

    Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y{sub 3}Fe{sub 5}O{sub 12} (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films.

  17. Magnetism of coherent Co and Ni thin films on Cu(111) and Au(111) substrates: An ab initio study

    Science.gov (United States)

    Zelený, Martin; Dlouhý, Ivo

    2017-02-01

    We present an ab initio study of structural and magnetic properties of coherent Co and Ni thin films on Cu(111) and Au(111) substrates with thicknesses of up to 6 monolayers. All studied films on Cu(111) substrates prefer structures close their ground state (hcp for Co and fcc for Ni), whereas only the hcp stacking sequence has been found for both films on Au(111) substrates. All studied films exhibit instability of the first monolayer with respect to decomposition into 2-monolayer- or 3-monolayer-high islands, which is in agreement with experimental findings. All studied films are also ferromagnetic, nevertheless the Ni/Cu(111) films reduce their magnetic moments in the layer adjacent to the substrate due to a stronger Cu-Ni interaction at the interface. The magnetic anisotropy of a Co film does not depend on the film thickness: all the studied Co/Au(111) films exhibit a perpendicular magnetic anisotropy, whereas all the Co/Cu(111) films prefer in-plane magnetization. On the other hand, both Ni films change their preference for in-plane orientation of their easy axis to out-of-plane orientation at a critical thickness of 2 monolayers, however, the magnetic anisotropy energies for films thicker than 1 monolayer are smaller than 1 meV/Ni atom. These behaviors of magnetic anisotropy do not depend on the structure of the studied films.

  18. Magnetic microstructures in electrodeposited Fe1 - xGax thin films (15 ≤ x ≤ 22 at.%)

    Science.gov (United States)

    Ranchal, R.; Fin, S.; Bisero, D.

    2015-02-01

    We have investigated the magnetic behavior of Fe1 - xGax (15 ≤ x ≤ 22 at.%) thin films grown by electrodeposition. The samples exhibit a texture although a rather small diffraction peak related to the (1 0 0) phase can also be observed. The layers do not present perpendicular magnetic anisotropy but magnetic hysteresis loops and magnetic force microscopy evidence a significant out-of-plane component for the magnetization. This component seems to increase for Ga contents around the 19 at.% value at which these alloys present a peak for the magnetostriction constant in the [1 0 0] direction. In this composition range, we have also observed an enhancement of the period of the magnetic structures. The experimental results indicate that the origin of the domain configuration is the presence of clusters with a (1 0 0) structural phase. The out-of-plane component of the magnetization seems to arise because of the compression of these nanoaggregates.

  19. Effect of Cu buffer layer on magnetic anisotropy of cobalt thin films deposited on MgO(001 substrate

    Directory of Open Access Journals (Sweden)

    Syed Sheraz Ahmad

    2016-11-01

    Full Text Available Cobalt thin films with 5 nm thickness were prepared on single-crystal MgO (001 substrates with different thickness Cu buffer (0 nm, 5 nm, 10 nm, 20 nm. The structure, magnetic properties and transport behaviors were investigated by employing low-energy-electron-diffraction (LEED, magneto-optical Kerr effect (MOKE and anisotropic magnetoresistance (AMR. By comparing the magnetic properties of the sample as-deposited (without Cu buffer layer one with those having the buffer Cu, we found that the magnetic anisotropy was extremely affected by the Cu buffer layer. The magnetic anisotropy of the as-deposited, without buffer layer, sample shows the uniaxial magnetic anisotropy (UMA. We found that the symmetry of the magnetic anisotropy is changed from UMA to four-fold when the thickness of the Cu buffer layer reaches to 20 nm. Meanwhile, the coercivity increased from 49 Oe (without buffer layer to 300 Oe (with 20 nm Cu buffer, in the easy axis direction, as the thickness of the buffer layer increases. Moreover, the magnitudes of various magnetic anisotropy constants were determined from torque curves on the basis of AMR results. These results support the phenomenon shown in the MOKE.

  20. Effect of Cu buffer layer on magnetic anisotropy of cobalt thin films deposited on MgO(001) substrate

    Science.gov (United States)

    Ahmad, Syed Sheraz; He, Wei; Zhang, Yong-Sheng; Tang, Jin; Gul, Qeemat; Zhang, Xiang-Qun; Cheng, Zhao-Hua

    2016-11-01

    Cobalt thin films with 5 nm thickness were prepared on single-crystal MgO (001) substrates with different thickness Cu buffer (0 nm, 5 nm, 10 nm, 20 nm). The structure, magnetic properties and transport behaviors were investigated by employing low-energy-electron-diffraction (LEED), magneto-optical Kerr effect (MOKE) and anisotropic magnetoresistance (AMR). By comparing the magnetic properties of the sample as-deposited (without Cu buffer layer) one with those having the buffer Cu, we found that the magnetic anisotropy was extremely affected by the Cu buffer layer. The magnetic anisotropy of the as-deposited, without buffer layer, sample shows the uniaxial magnetic anisotropy (UMA). We found that the symmetry of the magnetic anisotropy is changed from UMA to four-fold when the thickness of the Cu buffer layer reaches to 20 nm. Meanwhile, the coercivity increased from 49 Oe (without buffer layer) to 300 Oe (with 20 nm Cu buffer), in the easy axis direction, as the thickness of the buffer layer increases. Moreover, the magnitudes of various magnetic anisotropy constants were determined from torque curves on the basis of AMR results. These results support the phenomenon shown in the MOKE.

  1. Improved Resistance Switching Stability in Fe-Doped ZnO Thin Films Through Pulsed Magnetic Field Annealing.

    Science.gov (United States)

    Xu, Hongtao; Wu, Changjin; Xiahou, Zhao; Jung, Ranju; Li, Ying; Liu, Chunli

    2017-12-01

    Five percent of Fe-doped ZnO (ZnO:Fe) thin films were deposited on Pt/TiO2/SiO2/Si substrates by a spin-coating method. The films were annealed without (ZnO:Fe-0T) and with a pulsed magnetic field of 4 T (ZnO:Fe-4TP) to investigate the magnetic annealing effect on the resistance switching (RS) behavior of the Pt/ZnO:Fe/Pt structures. Compared with the ZnO:Fe-0T film, the ZnO:Fe-4TP film showed improved RS performance regarding the stability of the set voltage and the resistance of the high resistance state. Transmission electron microscopy and X-ray photoelectron spectroscopy analyses revealed that the ZnO:Fe-4TP film contains more uniform grains and a higher density of oxygen vacancies, which promote the easier formation of conducting filaments along similar paths and the stability of switching parameters. These results suggest that external magnetic fields can be used to prepare magnetic oxide thin films with improved resistance switching performance for memory device applications.

  2. Magnetic Properties of NiCuZn Ferrite Thin Films Prepared by the Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ni0.4Cu0.2Zn0.4Fe2O4 thin films were fabricated on Si substrates by using the sol-gel method and rapid thermal annealing (RTA), and their magnetic properties and crystalline structures were investigated.The samples calcined at and above 600 ℃ have a single-phase spinel structure and the average grain size of the sample calcined at 600 ℃ is about 20 nm. The initial permeability μi, saturation magnetization Ms and coercivity Hc of the samples increase with the increasing calcination temperature. The sample calcined at 600 ℃ exhibits an excellent soft magnetic performance, which has μi=33.97 (10 MHz),Hc=15.62 Oe and Ms=228.877 emu/cm3. Low-temperature annealing can enhance the magnetic properties of the samples. The work shows that using the sol-gel method in conjunction with RTA is a promising way to fabricate integrated thin-film devices.

  3. Perpendicular Magnetic Anisotropy in CoSiB/Pd/CoSiB Trilayer Thin Films with Varying Pd-Layer Thicknesses.

    Science.gov (United States)

    Jung, Sol; Kim, Taewan; Yim, Haein

    2015-11-01

    We investigate the magnetic properties of CoSiB (1 5-Å-thickness)/Pd (Pd thickness = 8, 11, 14, 17, 20, 24, 27, 29 and 33 Å)/CoSiB (15-Å-thickness) trilayer thin films. The CoSiB-layer thickness was fixed to 15 Å, while the Pd-layer thickness was varied from 8-33 Å. In this paper, we present a new type of thin film containing amorphous Co75Si15B10 and Pd. We investigate the magnetic properties of a fabricated CoSiB/Pd/CoSiB trilayer thin film with perpendicular magnetic anisotropy, and determine the correlation between the magnetic properties and the nonmagnetic Pd-layer thickness. With increasing Pd-layer thickness, both the coercivity and the saturation magnetization decreased. Furthermore, the maximum values of the magnetic anisotropy were calculated as 0.3 x 10(6) erg/cc. In order to examine the difference between the in-plane magnetic anisotropy and perpendicular magnetic anisotropy, magnetic force microscopy images of the CoSiB (15-Å-thickness)/Pd (Pd thickness = 8 and 14 Å)/CoSiB (15-Å-thickness) trilayer thin films were obtained.

  4. Magnetic properties of pure and Fe doped HoCrO3 thin films fabricated via a solution route

    Science.gov (United States)

    Yin, Shiqi; Sauyet, Theodore; Guild, Curt; Suib, S. L.; Jain, Menka

    2017-04-01

    Multiferroic properties of orthorhombically distorted perovskite rare-earth chromites, such as HoCrO3, are being investigated extensively in recent years. In the present work, we report on the effect of Fe substitution on the magnetic properties of HoCrO3 thin films. Thin films of HoCrO3 and HoCr0.7Fe0.3O3 were fabricated via a solution route on platinized silicon substrates. Structural properties of the films were evaluated by X-ray diffraction and Raman spectroscopy techniques. The surface morphology and cross-sections of the films were examined using scanning electron microscopy. Optical band gaps of pure and Fe doped HoCrO3 films are found to be 3.45 eV and 3.39 eV, respectively. The magnetization measurements show that the Néel temperatures (where Cr3+ orders) for the HoCrO3 and HoCr0.7Fe0.3O3 films are 134 and 148 K, respectively. In a magnetic field of 2 T, the maximum entropy change and relative cooling power, two parameters to evaluate the magnetocaloric properties of a material, were 0.813 J/kg K at 11 K and 21.1 J/kg for HoCrO3 film, in comparison with 0.748 J/kg K at 15 K and 26.8 J/kg for HoCr0.7Fe0.3O3 film. To our knowledge, this is the first work exploring the band gap and magnetocaloric properties of rare-earth chromite thin films. These findings should inspire the development of rare-earth chromite thin films for temperature control of nanoscale electronic devices and sensors in the low temperature region (< 30 K).

  5. Structural and magnetic properties of TiZrNi thin films prepared by magnetron sputtering and thermal annealing.

    Science.gov (United States)

    Shin, Hyemin; Choi, Soo-bin; Lee, Ik-jae; Yu, Chung-jong; Kim, Jae-yong

    2010-11-01

    Distinctive thin layers of TiZr and Ni were deposited by using a magnetron sputtering method and a thermal annealing was applied to discover metallic films of quasicrystals. After a heat treatment in vacuum, 70 nm thick deposited layers were well mixed with nominal compositions of 49.7, 29.3 and 21.0 for Ti, Zr and Ni, respectively, which is very close with the one forming a quasicrystalline phase. The magnetization values were significantly decreased from 0.286 to 0.142 emu/mm3 at 2000 Oe, after annealing, while a shape of magnetic hysteresis was maintained. It is believed that a different magnetic behavior after thermal annealing is due to the homogeneous mixing of atomic elements and possible existence of a metastable phase.

  6. Unraveling the magnetic properties of BiFe0.5Cr0.5O3 thin films

    Directory of Open Access Journals (Sweden)

    G. Vinai

    2015-11-01

    Full Text Available We investigate the structural, chemical, and magnetic properties on BiFe0.5Cr0.5O3 (BFCO thin films grown on (001 (110 and (111 oriented SrTiO3 (STO substrates by x-ray magnetic circular dichroism and x-ray diffraction. We show how highly pure BFCO films, differently from the theoretically expected ferrimagnetic behavior, present a very weak dichroic signal at Cr and Fe edges, with both moments aligned with the external field. Chemically sensitive hysteresis loops show no hysteretic behavior and no saturation up to 6.8 T. The linear responses are induced by the tilting of the Cr and Fe moments along the applied magnetic field.

  7. Structure of magneto-Keplerian discs: an analytical solution for thin accretion discs threatened by stellar magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Kaburaki, O.

    1986-05-15

    The structure of Keplerian discs which are threaded by the magnetic field lines of each central star are considered. Under the assumptions of thin discs, stationarity and of axisymmetry, a fairly simple analytical solution is found. In such a disc, the electromagnetic force does not play any important role in the radial force balance, but it is this force that maintains the disc structure in the latitudinal direction. As suggested by previous authors, the angular momentum transfer is controlled by the global structure of the magnetic field. In contrast to their results, however, the present solution does not predict the switching of the azimuthal component of the magnetic field as a function of the radial distance in the disc.

  8. Perpendicular Magnetic Anisotropy and Spin Glass-like Behavior in Molecular Beam Epitaxy Grown Chromium Telluride Thin Films.

    Science.gov (United States)

    Roy, Anupam; Guchhait, Samaresh; Dey, Rik; Pramanik, Tanmoy; Hsieh, Cheng-Chih; Rai, Amritesh; Banerjee, Sanjay K

    2015-04-28

    Reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM), vibrating sample magnetometry, and other physical property measurements are used to investigate the structure, morphology, magnetic, and magnetotransport properties of (001)-oriented Cr2Te3 thin films grown on Al2O3(0001) and Si(111)-(7×7) surfaces by molecular beam epitaxy. Streaky RHEED patterns indicate flat smooth film growth on both substrates. STM studies show the hexagonal arrangements of surface atoms. Determination of the lattice parameter from the atomically resolved STM image is consistent with the bulk crystal structures. Magnetic measurements show the film is ferromagnetic, having a Curie temperature of about 180 K, and a spin glass-like behavior was observed below 35 K. Magnetotransport measurements show the metallic nature of the film with a perpendicular magnetic anisotropy along the c-axis.

  9. Amorphous Si layers co-doped with B and Mn: Thin film growth and steering of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Drera, G. [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy); Mozzati, M.C. [CNISM, Dipartimento di Fisica, Università di Pavia, Via Bassi 6, 27100 Pavia (Italy); Colombi, P. [CSMT Gestione s.c.a.r.l, Via Branze 45, 25123 Brescia (Italy); Salvinelli, G.; Pagliara, S.; Visentin, D. [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy); Sangaletti, L., E-mail: sangalet@dmf.unicatt.it [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy)

    2015-09-01

    Amorphous silicon thin films co-doped with manganese (5% at.) and boron (1.8% at.) have been prepared by RF sputtering on Al{sub 2}O{sub 3} substrates held at room temperature (RT). The films, with an average thickness of about 0.9 μm, were carefully characterized by micro-Raman and X-ray photoemission spectroscopies. A ferromagnetic (FM) behavior up to RT was observed. In order to discuss and possibly rule out extrinsic effects usually related to segregations of ferromagnetic impurities in the samples, magnetization measurements were carried out on the Al{sub 2}O{sub 3} substrates, as well as on Si:B and Si:Mn films grown with the same RF sputtering system. Only the Si:B:Mn films displayed a FM behavior up to RT. Since amorphous films doped with Mn alone did not display any signature of FM ordering, boron co-doping results to be crucial for the onset of the FM behavior. The conductivity of the samples is not affected by boron doping that, therefore, does not appear to significantly contribute to a possible carrier-mediated FM interaction between Mn ions by supplying extra charges to the system. On this basis, the capability of B to hinder the quenching of the Mn 3d magnetic moments has also to be regarded as a possible role of this co-dopant in the observed magnetization. - Highlights: • We successfully deposited amorphous silicon thin films co-doped with Mn and B. • Structural, electronic, and magnetic properties have been carefully characterized. • A ferromagnetic behavior up to room temperature was detected. • The extrinsic origin of magnetism is excluded. • Boron can play a relevant role to avoid quenching of magnetic moment in Mn ions.

  10. Growth induced magnetic anisotropy in amorphous thin films. Annual progress report year 1, November 4, 1994--October 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, F. [Univ. of California, San Diego, La Jolla, CA (United States). Dept. of Physics

    1995-07-01

    The work in the past year has primarily involved three areas of magnetic thin films: amorphous rare earth-transition metal alloys, epitaxial COPt3 thin films, and exchange coupled antiferromagnetic insulators. In the amorphous alloys, the authors have focused on understanding the cause and the effect of the growth-surface-induced perpendicular magnetic anisotropy. Using the results of previous work, they are able to control this anisotropy quite precisely. This anisotropy is predicted to have dramatic and as-yet unobserved effects on the underlying nature of the magnetism. The work on the epitaxial Co-Pt alloys was originally undertaken as a comparison study to the amorphous alloys. The authors have discovered that these alloys exhibit a remarkable new phenomena; a surface-induced miscibility gap in a material which is believed to be completely miscible in the bulk. This miscibility gap is 100% correlated with the perpendicular anisotropy, although the connection is not yet clear, and is presumably linked to a magnetic energy of mixing which tends to drive a material towards clustering. The problem of exchange coupling in multilayers impacts many of the current research areas in magnetism. NiO/CoO multilayers can be prepared with coherent interfaces. The specific heat shows unambiguously the ordering of the spins in the layers. The results show clearly the transition from a single transition temperature to two distinct transitions with increasing thickness of the individual layers. From this data, the authors are able to determine the interface magnetic exchange coupling constant and the effect on the transition temperature of finite layer thickness.

  11. Control of the magnetic properties of LaMnO3 epitaxial thin films grown by Pulsed Laser Deposition

    Science.gov (United States)

    Martinez, Benjamin; Roqueta, Jaume; Pomar, Alberto; Balcells, Lluis; Frontera, Carlos; Konstantinovic, Zorica; Sandiumenge, Felip; Santiso, Jose; Advanced materials characterization Team; Thin films growth Team

    2015-03-01

    LaMnO3 (LMO), the parent compound of colossal magnetoresistance based manganites has gained renewed attention as a building block in heterostructures with unexpected properties. In its bulk phase, stoichiometric LMO is an A-type antiferromagnetic (AFM) insulator (TN = 140K) with orthorhombic structure that easily accommodate an oxygen excess by generating cationic (La or Mn) vacancies. As a result, a fraction of Mn 3+ changes to Mn 4+ leading to a double-exchange mediated ferromagnetic (FM) behavior. In thin films the AFM phase has been elusive up to now and thin films with FM ordering are usually reported. In this work, we have systematically studied the growth process of LaMnO3 thin films by pulsed laser deposition on SrTiO3 (001) substrates under different oxygen partial pressures (PO2) . A close correlation between the structure (explored by XRD) and the magnetic properties (SQUID measurements) of the films with PO2 has been identified. At high PO2 FM behavior is observed. In contrast, at very low PO2, the results obtained for unit cell volume (close to stoichiometric bulk values) and magnetic moment (0.2 μB/Mn) strongly indicate antiferromagnetic ordering. We acknowledge financial support from the Spanish MINECO (MAT2012-33207).

  12. Gd doping effect on structural, electrical and magnetic properties of ZnO thin films synthesized by sol-gel spin coating technique

    Science.gov (United States)

    Kumar, Sanjeev; Thangavel, Rajalingam

    2017-03-01

    Nanocrystalline Gd-doped ZnO thin films were deposited on sapphire (0001) substrates using sol-gel spin coating technique. The structural and optical properties of deposited thin films were characterized by X-ray diffraction (XRD) and micro Raman spectroscopy. Structural and optical studies show that the doped Gd ions occupy Zn sites retaining the wurtzite symmetry. Photoluminescence (PL) studies reveal the presence of oxygen vacancies in Gd doped ZnO thin films. The resistivity of Gd doped ZnO thin film decreases with increase in Gd doping upto 4%. Gd-doped ZnO films demonstrate weak magnetic ordering at room temperature.

  13. Influence of substrate temperature on structure, microstructure and magnetic properties of sputtered Fe–Ga thin films

    Energy Technology Data Exchange (ETDEWEB)

    Basumatary, Himalay [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad (India); Department of Materials Engineering, Indian Institute of Science, Bangalore (India); Arout Chelvane, J., E-mail: aroutchelvane@gmail.com [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad (India); Sridhara Rao, D.V.; Kamat, S.V. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad (India); Ranjan, R. [Department of Materials Engineering, Indian Institute of Science, Bangalore (India)

    2015-06-15

    This paper reports the structure, microstructure and magnetic properties of Fe–Ga thin films deposited using DC magnetron sputtering technique on Si(100) substrate kept at different temperatures. Structural studies employing X-ray diffraction and TEM revealed the presence of only disordered A2 phase in the film. Columnar growth of nanocrystalline grains from the substrate was observed in the film deposited at room temperature. With increase in substrate temperature the grain size as well as surface roughness was found to increase. The magnetization of the films deposited at higher substrate temperatures were found to saturate at lower magnetic field as compared to the room temperature deposited film. Coercivity was found to decrease with increasing substrate temperature upto a minimum value of ~2 Oe for the film deposited at 450 °C and with further increase in substrate temperature it was found to increase. A maximum magnetostriction of 200 µ-strains was also observed for the film deposited at 450 °C. - Highlights: • Columnar growth of nano-crystalline grains of A2 phase observed in the films. • Coercivity is found to be influenced by grain size and surface roughness of the films. • A very low coercivity (~2 Oe) and a large magnetostriction (~200 µ-strains) has been achieved in films grown at 450 °C which are very important and desirable properties for a magnetostrictive thin film.

  14. Magnetic and structural properties of Co{sub 2}FeAl thin films grown on Si substrate

    Energy Technology Data Exchange (ETDEWEB)

    Belmeguenai, Mohamed, E-mail: belmeguenai.mohamed@univ-paris13.fr [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France); Tuzcuoglu, Hanife [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France); Gabor, Mihai; Petrisor, Traian [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Street Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Tiusan, Coriolan [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Street Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Université de Nancy, BP 70239, F-54506 Vandoeuvre (France); Berling, Dominique [IS2M (CNRS-LRC 7228), 15 rue Jean Starcky, Université de Haute-Alsace, BP 2488, 68057 Mulhouse-Cedex (France); Zighem, Fatih; Mourad Chérif, Salim [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France)

    2015-01-01

    The correlation between magnetic and structural properties of Co{sub 2}FeAl (CFA) thin films of different thicknesses (10 nmmagnetic fields revealed that the effective magnetization and the uniaxial in-plane anisotropy field follow a linear variation versus the inverse CFA thickness. This allows deriving a perpendicular surface anisotropy coefficient of −1.86 erg/cm{sup 2}. - Highlights: • Various Co{sub 2}FeAl thin films were grown on a Si(001) substrates and annealed at 600 °C. • The thickness dependence of magnetic and structural properties has been studied. • X-ray measurements revealed an (011) out-of-plane textured growth of the films. • The easy axis coercive field varies linearly with the inverse CFA thickness. • The effective magnetization increases linearly with the inverse film thickness.

  15. Ti-doped ZnO Thin Films Prepared at Different Ambient Conditions: Electronic Structures and Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Zhihua Yong

    2010-06-01

    Full Text Available We present a comprehensive study on Ti-doped ZnO thin films using X-ray Absorption Fine Structure (XAFS spectroscopy. Ti K edge XAFS spectra were measured to study the electronic and chemical properties of Ti ions in the thin films grown under different ambient atmospheres. A strong dependence of Ti speciation, composition, and local structures upon the ambient conditions was observed. The XAFS results suggest a major tetrahedral coordination and a 4+ valence state. The sample grown in a mixture of 80% Ar and 20% O2 shows a portion of precipitates with higher coordination. A large distortion was observed by the Ti substitution in the ZnO lattice. Interestingly, the film prepared in 80% Ar, 20% O2 shows the largest saturation magnetic moment of 0.827 ± 0.013 µB/Ti.

  16. The scattering of $f$- and $p$-modes from ensembles of thin magnetic flux tubes - An analytical approach

    CERN Document Server

    Hanson, Chris S

    2014-01-01

    Motivated by the observational results of Braun (1995), we extend the model of Hanson & Cally (2014) to address the effect of multiple scattering of f and p-modes by an ensemble of thin vertical magnetic flux tubes in the surface layers of the Sun. As in observational Hankel analysis we measure the scatter and phase shift from an incident cylindrical wave in a coordinate system roughly centred in the core of the ensemble. It is demonstrated that, although thin flux tubes are unable to interact with high order fluting modes individually, they can indirectly absorb energy from these waves through the scatters of kink and sausage components. It is also shown how the distribution of absorption and phase shift across the azimuthal order m depends strongly on the tube position, as well as on the individual tube characteristics. This is the first analytical study into an ensembles multiple scattering regime, that is embedded within a strati?ed atmosphere.

  17. The scattering of f- and p-modes from ensembles of thin magnetic flux tubes: an analytical approach

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Chris S.; Cally, Paul S., E-mail: christopher.hanson@monash.edu [Monash Centre for Astrophysics and School of Mathematical Sciences, Monash University, Clayton, Victoria 3800 (Australia)

    2014-08-20

    Motivated by the observational results of Braun, we extend the model of Hanson and Cally to address the effect of multiple scattering of f and p modes by an ensemble of thin vertical magnetic flux tubes in the surface layers of the Sun. As in the observational Hankel analysis, we measure the scatter and phase shift from an incident cylindrical wave in a coordinate system roughly centered in the core of the ensemble. It is demonstrated that although thin flux tubes are unable to interact with high-order fluting modes individually, they can indirectly absorb energy from these waves through the scatters of kink and sausage components. It is also shown how the distribution of absorption and phase shift across the azimuthal order m depends strongly on the tube position as well as on the individual tube characteristics. This is the first analytical study into an ensembles multiple-scattering regime that is embedded within a stratified atmosphere.

  18. Oxygen vacancy induced magnetism in BaTiO3-δ and Nb:BaTiO3-δ thin films

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The unusual magnetic properties are observed in oxygen deficient BaTiO3-δ(BTO) and Nb:BaTiO3-δ(BNTO) thin films fabricated on SrTiO3 substrates by laser molecular beam epitaxy.The distinct magnetic hysteresis loops are observed in the oxygen deficient BTO and BNTO thin films in a temperature range of 5 to 300 K,whereas the diamagnetism is observed in both BTO and BNTO annealed at 1 atm of oxygen.The dopant Nb only enhances the magnetization in BNTO thin films,but has little effect on the coercivity.The magnetism of BTO and BNTO films is proposed to be the oxygen vacancies by origin.

  19. Thickness dependence of magnetic anisotropy and domains in amorphous Co40Fe40B20 thin films grown on PET flexible substrates

    Science.gov (United States)

    Tang, Zhenhua; Ni, Hao; Lu, Biao; Zheng, Ming; Huang, Yong-An; Lu, Sheng-Guo; Tang, Minghua; Gao, Ju

    2017-03-01

    The amorphous Co40Fe40B20 (CoFeB) films (5-200 nm in thickness) were grown on flexible polyethylene terephthalate (PET) substrates using the DC magnetron-sputtering method. The thickness dependence of structural and magnetic properties of flexible CoFeB thin films was investigated in detail. The in-plane uniaxial magnetic anisotropy induced by strain as a function of thickness was obtained in flexible CoFeB thin films, and a critical thickness of 150 nm for in-plane magnetic anisotropy was observed. Moreover, the domains and the uniaxial anisotropy as a function of angular direction of applied magnetic field were characterized. The results show potential for designing CoFeB-based flexible spintronic devices in which the physical parameters could be tailored by controlling the thickness of the thin film.

  20. Magnetic properties of Sm-Co thin films grown on MgO(100) deposited from a single alloy target

    Energy Technology Data Exchange (ETDEWEB)

    Verhagen, T. G. A.; Boltje, D. B.; Ruitenbeek, J. M. van; Aarts, J., E-mail: aarts@physics.leidenuniv.nl [Huygens-Kamerlingh Onnes Laboratorium, Universiteit Leiden, P.O. Box 9504, 2300 RA Leiden (Netherlands)

    2014-08-07

    We have grown epitaxial Sm-Co thin films by sputter deposition from a single alloy target with a nominal SmCo{sub 5} composition on Cr(100)-buffered MgO(100) single-crystal substrates. By varying the Ar gas pressure, we can change the composition of the film from a SmCo{sub 5}-like to a Sm{sub 2}Co{sub 7}-like phase. The composition, crystal structure, morphology, and magnetic properties of these films have been determined using Rutherford Backscattering, X-ray diffraction, and magnetization measurements. We find that we can grow films with, at room temperature, coercive fields as high as 3.3 T, but with a remanent magnetization which is lower than can be expected from the texturing. This appears to be due to the Sm content of the films, which is higher than expected from the content of the target, even at the lowest possible sputtering pressures. Moreover, we find relatively large variations of film properties using targets of nominally the same composition. At low temperatures, the coercive fields increase, as expected for these hard magnets, but in the magnetization, we observe a strong background signal from the paramagnetic impurities in the MgO substrates.

  1. Magnetic properties of Sm-Co thin films grown on MgO(100) deposited from a single alloy target

    Science.gov (United States)

    Verhagen, T. G. A.; Boltje, D. B.; van Ruitenbeek, J. M.; Aarts, J.

    2014-08-01

    We have grown epitaxial Sm-Co thin films by sputter deposition from a single alloy target with a nominal SmCo5 composition on Cr(100)-buffered MgO(100) single-crystal substrates. By varying the Ar gas pressure, we can change the composition of the film from a SmCo5-like to a Sm2Co7-like phase. The composition, crystal structure, morphology, and magnetic properties of these films have been determined using Rutherford Backscattering, X-ray diffraction, and magnetization measurements. We find that we can grow films with, at room temperature, coercive fields as high as 3.3 T, but with a remanent magnetization which is lower than can be expected from the texturing. This appears to be due to the Sm content of the films, which is higher than expected from the content of the target, even at the lowest possible sputtering pressures. Moreover, we find relatively large variations of film properties using targets of nominally the same composition. At low temperatures, the coercive fields increase, as expected for these hard magnets, but in the magnetization, we observe a strong background signal from the paramagnetic impurities in the MgO substrates.

  2. Influence of annealing temperature on the magnetic properties of Cr{sup +} implanted AlN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shah, A., E-mail: attaullah77@yahoo.com [National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad (Pakistan); Mahmood, Arshad; Ali, Zahid; Ashraf, T. [National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad (Pakistan); Ahmed, Ishaq [Experimental Physics Lab, National Center for Physics (NCP), Islamabad (Pakistan); Mehmood, Mazhar [DMME, Pakistan Institute of Engineering and Applied Science (PIEAS), PO Nilore, Islamabad Pakistan (Pakistan); Rashid, Rashad [National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad (Pakistan); Shakir, Imran, E-mail: shakir@skku.edu [Sustainable Energy Technologies (SET) center building No 3, Room 1c23, College of Engineering, King Saud University, PO-BOX 800, Riyadh 11421 (Saudi Arabia)

    2015-04-01

    Diluted magnetic semiconductor (DMS) AlN:Cr films were produced by implanting various doses Cr{sup +} ions into AlN thin films at room temperature followed by a thermal annealing process. The structural and magnetic characteristics of the samples were investigated as a function of annealing temperature by means of Rutherford backscattering and channeling spectrometry (RBS/C), X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometer (VSM) and SQUID. Structural analyzes demonstrate that implantation damages gradually decrease with the increasing of annealing temperature. Moreover, better recrystallization in the implanted part of the samples was observed for the sample annealed at 950 °C. Both XRD and Raman pattern illustrate that no secondary phase or metal related-peaks were appear in all the samples. Magnetic analysis reveals that annealed Cr{sup +}-implanted samples exhibit ferromagnetism at room temperature, however, the sample annealed at 950 °C shows improved magnetic characteristics. The saturation magnetization is estimated to be 9.0×10{sup −5} emu/g and the coercive field (H{sub c}) is approximately 200 Oe for the samples annealed 950 °C. In SQUID analysis, FC/ZFC measurements indicate that the Curie temperature (T{sub C}) is well above room temperature.

  3. All-in-all-out magnetic domain size in pyrochlore iridate thin films as probed by local magnetotransport

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, T. C.; Uchida, M., E-mail: uchida@ap.t.u-tokyo.ac.jp; Kozuka, Y.; Ogawa, S. [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Tsukazaki, A. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); PRESTO, Japan Science and Technology Agency (JST), Tokyo 102-0075 (Japan); Arima, T. [Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561 (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Kawasaki, M. [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan)

    2016-01-11

    Pyrochlore iridates have attracted growing attention because of a theoretical prediction of a possible topological semimetal phase originating from all-in-all-out spin ordering. Related to the topological band structure, recent findings of the magnetic domain wall conduction have stimulated investigations of magnetic domain distribution in this system. Here, we investigate the size of magnetic domains in Eu{sub 2}Ir{sub 2}O{sub 7} single crystalline thin films by magnetoresistance (MR) using microscale Hall bars. Two distinct magnetic domains of the all-in-all-out spin structure are known to exhibit linear MR but with opposite signs, which enables us to estimate the ratio of the two domains in the patterned channel. The linear MR for 80 × 60 μm{sup 2} channel is nearly zero after zero-field cooling, suggesting random distribution of domains smaller than the channel size. In contrast, the wide distribution of the value of the linear MR is detected in 2 × 2 μm{sup 2} channel, reflecting the detectable domain size depending on each cooling-cycle. Compared to simulation results, we estimate the average size of a single all-in-all-out magnetic domain as 1–2 μm.

  4. X-ray absorption spectroscopy and magnetic circular dichroism studies of L1{sub 0}-Mn-Ga thin films

    Energy Technology Data Exchange (ETDEWEB)

    Glas, M., E-mail: mglas@physik.uni-bielefeld.de; Sterwerf, C.; Schmalhorst, J. M.; Reiss, G. [Thin Films and Physics of Nanostructures, Bielefeld University, Bielefeld (Germany); Ebke, D. [Thin Films and Physics of Nanostructures, Bielefeld University, Bielefeld (Germany); Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Jenkins, C.; Arenholz, E. [ALS Berkeley, California 94720-8229 (United States)

    2013-11-14

    Tetragonally distorted Mn{sub 3−x}Ga{sub x} thin films with 0.1magnetic anisotropy and low magnetization and thus have the potential to serve as electrodes in spin transfer torque magnetic random access memory. Because a direct capping of these films with MgO is problematic due to oxide formation, we examined the influence of a CoFeB interlayer and of two different deposition methods for the MgO barrier on the formation of interfacial Mn-O for Mn{sub 62}Ga{sub 38} by element specific X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD). A highly textured L1{sub 0} crystal structure of the Mn-Ga films was verified by X-ray diffraction measurements. For samples with e-beam evaporated MgO barrier no evidence for Mn-O was found whereas in samples with magnetron sputtered MgO, Mn-O was detected, even for the thickest interlayer thickness. Both XAS and XMCD measurements showed an increasing interfacial Mn-O amount with decreasing CoFeB interlayer thickness. Additional element specific full hysteresis loops determined an out-of-plane magnetization axis for the Mn and Co, respectively.

  5. Growth and magnetic anisotropy of thin W(110)/Co films on Al2O3(112¯0)

    Science.gov (United States)

    Sellmann, R.; Fritzsche, H.; Maletta, H.; Leiner, V.; Siebrecht, R.

    2001-06-01

    The growth and magnetism of thin W(110)/Co films deposited by molecular beam epitaxy on single-crystal sapphire Al2O3(112¯0) substrates is investigated. Low-energy electron diffraction analysis shows that the Co films grow on the epitaxial W(110) substrate layer with a constant lattice strain up to a Co thickness dCo=20 Å. Pseudomorphic growth is found for the W[11¯0] direction. The thickness-dependent magnetic anisotropy is studied in situ at T=300 K by means of magneto-optical Kerr-effect measurements on a Co wedge-shaped sample prior and after coverage with a Au overlayer. After the coverage the Co wedge reveals a perpendicular magnetic anisotropy for small Co film thickness followed by a spin-reorientation transition from out-of-plane to in-plane alignment of the magnetization vector in the thickness regime 7 Å<=dCo<=9 Å. Spin-dependent neutron reflectivity data provide evidence for a pronounced magnetic anisotropy within the film plane even for relatively thick Co films. The observed decrease of the splitting between spin-up and spin-down reflectivities for decreasing temperature indicates that the spin-reorientation transition of the system W(110)/Co/Au can also be induced thermally.

  6. X-ray absorption spectroscopy and magnetic circular dichroism studies of L10-Mn-Ga thin films

    Science.gov (United States)

    Glas, M.; Sterwerf, C.; Schmalhorst, J. M.; Ebke, D.; Jenkins, C.; Arenholz, E.; Reiss, G.

    2013-11-01

    Tetragonally distorted Mn3-xGax thin films with 0.1magnetic anisotropy and low magnetization and thus have the potential to serve as electrodes in spin transfer torque magnetic random access memory. Because a direct capping of these films with MgO is problematic due to oxide formation, we examined the influence of a CoFeB interlayer and of two different deposition methods for the MgO barrier on the formation of interfacial Mn-O for Mn62Ga38 by element specific X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD). A highly textured L10 crystal structure of the Mn-Ga films was verified by X-ray diffraction measurements. For samples with e-beam evaporated MgO barrier no evidence for Mn-O was found whereas in samples with magnetron sputtered MgO, Mn-O was detected, even for the thickest interlayer thickness. Both XAS and XMCD measurements showed an increasing interfacial Mn-O amount with decreasing CoFeB interlayer thickness. Additional element specific full hysteresis loops determined an out-of-plane magnetization axis for the Mn and Co, respectively.

  7. Shape-induced ultrahigh magnetic anisotropy and ferromagnetic resonance frequency of micropatterned thin Permalloy films

    NARCIS (Netherlands)

    Zhuang, Y.; Vroubel, M.; Rejaei, B.; Burghartz, J.N.; Attenborough, K.

    2006-01-01

    Magnetic anisotropy Hk>200 Oe was observed from bar-shaped Permalloy strips. The film was deposited on sputtered Cr seed layer by electroplating under ∼ 800 Oe external magnetic field. Tiny degradation of Hk was observed after 30 min postannealing at 400 °C in the absence of external magnetic field.

  8. Thermodynamic conditions during growth determine the magnetic anisotropy in epitaxial thin-films of La0.7Sr0.3MnO3

    Science.gov (United States)

    Vila-Fungueiriño, J. M.; Tinh Bui, Cong; Rivas-Murias, B.; Winkler, E.; Milano, J.; Santiso, J.; Rivadulla, F.

    2016-08-01

    The suitability of a particular material for use in magnetic devices is determined by the process of magnetization reversal/relaxation, which in turn depends on the magnetic anisotropy. Therefore, designing new ways to control magnetic anisotropy in technologically important materials is highly desirable. Here we show that magnetic anisotropy of epitaxial thin-films of half-metallic ferromagnet La0.7Sr0.3MnO3 (LSMO) is determined by the proximity to thermodynamic equilibrium conditions during growth. We performed a series of x-ray diffraction and ferromagnetic resonance (FMR) experiments in two different sets of samples: the first corresponds to LSMO thin-films deposited under tensile strain on (0 0 1) SrTiO3 by pulsed laser deposition (PLD; far from thermodynamic equilibrium); the second were deposited by a slow chemical solution deposition (CSD) method, under quasi-equilibrium conditions. Thin films prepared by PLD show fourfold in-plane magnetic anisotropy, with an overimposed uniaxial term. However, the uniaxial anisotropy is completely suppressed in the CSD films. This change is due to a different rotation pattern of MnO6 octahedra to accommodate epitaxial strain, which depends not only on the amplitude of tensile stress imposed by the STO substrate, but also on the growth conditions. Our results demonstrate that the nature and magnitude of the magnetic anisotropy in LSMO can be tuned by the thermodynamic parameters during thin-film deposition.

  9. Insight into the origin of magnetism in Iron-doped cadmium sulfide thin films from first principles calculations

    Science.gov (United States)

    Kanoun, Mohammed Benali

    2017-03-01

    We report a theoretical study of electronic structures and magnetic properties of Fe-doped CdS (10-10) thin films using first principle calculations within the density functional theory. It is shown that Fe atoms occupying Cd sites prefer to reside on the surface and couple antiferromagnetically. However, our results show the existence of competition between ferromagnetic and antiferromagnetic coupling because of the smaller total energy difference. Moreover, our density of states shows the existence of a simultaneous hybridization between the Fe d and S p states near the Fermi level.

  10. Development and validation of a radial inflow turbine model for simulation of the SNL S-CO2 split-flow loop.

    Energy Technology Data Exchange (ETDEWEB)

    Vilim, R. B. (Nuclear Engineering Division)

    2012-07-31

    A one-dimensional model for a radial inflow turbine has been developed for super-critical carbon dioxide (S-CO{sub 2}) Brayton cycle applications. The model accounts for the main phenomena present in the volute, nozzle, and impeller of a single-stage turbine. These phenomena include internal losses due to friction, blade loading, and angle of incidence and parasitic losses due to windage and blade-housing leakage. The model has been added as a component to the G-PASS plant systems code. The model was developed to support the analysis of S-CO{sub 2} cycles in conjunction with small-scale loop experiments. Such loops operate at less than a MWt thermal input. Their size permits components to be reconfigured in new arrangements relatively easily and economically. However, the small thermal input combined with the properties of carbon dioxide lead to turbomachines with impeller diameters of only one to two inches. At these sizes the dominant phenomena differ from those in larger more typical machines. There is almost no treatment in the literature of turbomachines at these sizes. The present work therefore is aimed at developing turbomachine models that support the task of S-CO{sub 2} cycle analysis using small-scale tests. Model predictions were compared against data from an experiment performed for Sandia National Laboratories in the split-flow Brayton cycle loop currently located at Barber-Nichols Inc. The split-flow loop incorporates two turbo-alternator-compressor (TAC) units each incorporating a radial inflow turbine and a radial flow compressor on a common shaft. The predicted thermodynamic conditions at the outlet of the turbine on the main compressor shaft were compared with measured values at different shaft speeds. Two modifications to the original model were needed to better match the experiment data. First, a representation of the heat loss from the volute downstream of the sensed inlet temperature was added. Second, an empirical multiplicative factor was

  11. Magnetization dynamics across the first order phase transition in FeRh thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pressacco, Federico

    2014-08-01

    The metallic alloy FeRh undergoes a phase transition from an antiferromagnetic phase (AFP) to a ferromagnetic phase (FP) when heated above 400 K. The change in magnetic order results in a change in the net magnetization of the system from zero up to 1.2 kA/m after increasing the system temperature. This is an uncommon characteristic for a magnetic material since usually one observes a decrease of the magnetization upon heating. This discloses the possibility to apply FeRh to Heat-Assisted Magnetic Recording (HAMR) devices.

  12. The magnetisation profiles and ac magnetisation losses in a single layer YBCO thin film caused by travelling magnetic field waves

    Science.gov (United States)

    Wang, Wei; Coombs, Timothy

    2015-05-01

    This paper studies the magnetisation and ac magnetisation losses caused by a travelling magnetic wave on a single-layer YBCO thin film. This work provides thorough investigations on how the critical magnetic field gradient has been changed by the application of a travelling wave. Several conditions were studied such as zero-field cooling (ZFC), field cooling (FC) and a delta-shaped trapped field. It was found that the travelling wave tends to attenuate the existing critical magnetic field gradients in all these conditions. This interesting magnetic behaviour can be well predicted by the finite element (FEM) software with the E-J power law and Maxwell’s equations. The numerical simulations show that the existing critical current density has been compromised after applying the travelling wave. The magnetisation profile caused by the travelling wave is very different from the standing wave, while the magnetisation based on the standing wave can be interpreted by the Bean model and constant current density assumption. Based on the numerical method, which has reliability that has been solidly proven in the study, we have extended the study to the ac magnetisation losses. Comparisons were made between the travelling wave and the standing wave for this specific YBCO sample. It was found that by applying the magnetic wave of the same amplitude, the ac magnetisation loss caused by the travelling wave is about 1/3 of that caused by the standing wave. These results are helpful in understanding the general magnetism problems and ac magnetisation loss in the travelling magnetic wave conditions such as inside a high temperature superconducting (HTS) rotating machine, etc.

  13. Thickness dependence of the magnetic properties of high-coercive Pr-Fe-B thin films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, F. [Shenyang National Laboratory for Materials Science, Institute of Metal Research and International Centre for Materials Physics, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang Liaoning 110016 (China); Liu, W. [Shenyang National Laboratory for Materials Science, Institute of Metal Research and International Centre for Materials Physics, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang Liaoning 110016 (China)], E-mail: wliu@imr.ac.cn; Cui, W.B.; Feng, J.N.; Zhang, Y.Q.; Zhang, Z.D [Shenyang National Laboratory for Materials Science, Institute of Metal Research and International Centre for Materials Physics, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang Liaoning 110016 (China)

    2008-10-01

    The magnetic properties of Pr-Fe-B films with perpendicular magnetic anisotropy have been studied as a function of thickness varying from 10 to 1200 nm. The crucial thickness for forming the Pr{sub 2}Fe{sub 14}B phase is estimated to be about 25 nm in our study, and the perpendicular anisotropy shows a trend to vanish for thick films. The coercivity of the films initially increases with increasing film thickness, gradually reaching a value which is near the value for bulk material. The magnetic domain size increases with increasing thickness. The surface morphology, the roughness and the domain structure of the films have been investigated by means of atomic-force microscopy and magnetic-force microscopy.

  14. Magnetic inhomogeneity in a multiferroic EuTiO3 thin film

    Science.gov (United States)

    Geng, Yanan; Lee, J. H.; Schlom, D. G.; Freeland, J. W.; Wu, Weida

    2013-03-01

    We report on variable temperature magnetic force microscopy studies of a strain-enabled multiferroic EuTiO3 film epitaxially grown on a (110)-oriented DyScO3 substrate. Our temperature- and magnetic-field-dependent studies clearly reveal an inhomogeneous magnetic state with the coexistence of ferromagnetic and nonferromagnetic states at low magnetic fields, which provides a microscopic origin of the anomalous missing moment in previous studies [Lee , Nature (London)0028-083610.1038/nature09331 466, 954 (2010)]. The spins of the nonferromagnetic phase can be aligned by modest magnetic fields (>1.5 T). The observed magnetic inhomogeneity probably originates from the coexistence of nearly degenerate magnetic ground states.

  15. Magnetocrystalline Anisotropy of Magnetic Grains in Co80Pt20:Oxide Thin Films Probed by X-ray Magnetic Circular Dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W.; Morton, S. A.; Wong, P. K. J.; Arenholz, E.; Lu, B.; Cheng, T. Y.; Xu, Y. B.; Laan, G. van der; Hu, X.F

    2011-01-12

    Using angle-dependent x-ray magnetic circular dichroism, we have measured magnetic hysteresis loops at the Co L2,3 edges of oxide-doped Co80Pt20 thin films. The magnetocrystalline anisotropy energy (MAE) of the Co atoms, which is the main source of the magnetocrystalline anisotropy of the CoPt magnetic grains, has been determined directly from these element-specific hysteresis loops. When the oxide volume fraction (OVF) is increased from 16.6% to 20.7%, the Co MAE has been found to decrease from 0.117 meV/atom to 0.076 meV/atom. While a larger OVF helps one to achieve a smaller grain size, it reduces the magnetocrystalline anisotropy, as demonstrated unambiguously from the direct Co MAE measurements. Our results suggest that those Co80Pt20:oxide films with an OVF between 19.1% and 20.7% are suitable candidates for high-density magnetic recording.

  16. Stresses evolution at high temperature (200°C on the interface of thin films in magnetic components

    Directory of Open Access Journals (Sweden)

    Doumit Nicole

    2014-07-01

    Full Text Available In the field of electronics, the increase of operating temperatures is a major industrial and scientific challenge because it allows reducing mass and volume of components especially in the aeronautic domain. So minimizing our components reduce masses and the use of cooling systems. For that, the behaviours and interface stresses of our components (in particular magnetic inductors and transformers that are constituted of one magnetic layer (YIG or an alumina substrate (Al2O3 representing the substrate and a thin copper film are studied at high temperature (200°C. COMSOL Multiphysics is used to simulate our work and to validate our measurements results. In this paper, we will present stresses results according to the geometrical copper parameters necessary for the component fabrication. Results show that stresses increase with temperature and copper’s thickness while remaining always lower than 200MPa which is the rupture stress value.

  17. Characterization of thin-film multilayers using magnetization curves and modeling of low-angle X-ray diffraction data

    Energy Technology Data Exchange (ETDEWEB)

    Lane, M. [Emory & Henry College, VA (United States); Chaiken, A.; Michel, R.P. [Lawrence Livermore National Lab., CA (United States)

    1994-12-01

    We have characterized thin-film multilayers grown by ion-beam sputtering using magnetization curves and modeling of low-angle x-ray diffraction data. In our films, we use ferromagnetic layer = Co, Fe, and NiFe and spacer layer = Si, Ge, FeSi{sub 2}, and CoSi{sub 2}. We have studied the effects of (1) deposition conditions; (2) thickness of layers; (3) different layer materials; and (4) annealing. We find higher magnetization in films grown at 1000V rather than 500V and in films with spacer layers of 50{angstrom} rather than 100{angstrom}. We find higher coercivity in films with cobalt grown on germanium rather than silicon, metal grown on gold underlayers rather than on glass substrates, and when using thinner spacer layers. Finally, modeling reveals that films grown with disilicide layers are more thermally stable than films grown with silicon spacer layers.

  18. Implantation of anatase thin film with 100 keV {sup 56}Fe ions: Damage formation and magnetic behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, J. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden)], E-mail: Jens.Jensen@telia.com; Sanz, R. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, ES-28049 Madrid (Spain); Martin, D. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Surpi, A. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Department of Biology and Chemical Engineering, Maelardalens Hoegskola, SE-632 20 Eskilstuna (Sweden); Kubart, T. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Vazquez, M. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, ES-28049 Madrid (Spain); Hernandez-Velez, M. [Applied Physics Department, Universidad Autonoma de Madrid, ES-28049 Madrid (Spain)

    2009-08-15

    We have investigated the damage morphology and magnetic properties of titanium dioxide thin films following implantation with Fe ions. The titanium dioxide films, having a polycrystalline anatase structure, were implanted with 100 keV {sup 56}Fe{sup +} ions to a total fluence of 1.3 x 10{sup 16} ions/cm{sup 2}. The ion bombardment leads to an amorphized surface with no indication of the presence of secondary phases or Fe clusters. The ion-beam induced damage manifested itself by a marked change in surface morphology and film thickness. A room temperature ferromagnetic behaviour was observed by SQUID in the implanted sample. It is believed that the ion-beam induced damage and defects in the polycrystalline anatase film were partly responsible for the observed magnetic response.

  19. Laser-induced precession of magnetization in ferrimagnetic GdFe thin films with low power excitation

    Directory of Open Access Journals (Sweden)

    K. Nishibayashi

    2013-03-01

    Full Text Available We have investigated thermal effects on the dynamics of laser-induced precession of magnetization in ferrimagnetic GdFe thin films under low-excitation conditions (6-60 μJ/cm2. An increase in quasi-equilibrium temperature by laser heating causes a shift in precession frequency, which is explained analytically by the alteration of the magnetic anisotropy field by 2.2 [Oe] at a pulse fluence of 1 μJ/cm2. We have also demonstrated coherent control of the precession amplitude using a sequence of two laser pulses, each with a fluence of 18 μJ/cm2, and point out the importance of low-power excitation for precise control of the dynamic states.

  20. Structural and magnetic properties of epitaxial delafossite CuFeO{sub 2} thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Toyanath; Senty, Tess R.; Trappen, Robbyn; Zhou, Jinling; Borisov, Pavel; Holcomb, Mikel B.; Bristow, Alan D.; Lederman, David [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Chen, Song; Song, Xueyan [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506-6070 (United States); Ferrari, Piero; Cabrera, Alejandro L. [Pontificia Universidad Catolica, Instituto de Física, Santiago (Chile)

    2015-01-07

    Growth of pure phase delafossite CuFeO{sub 2} thin films on Al{sub 2}O{sub 3} (00.1) substrates by pulsed laser deposition was systematically investigated as a function of growth temperature and oxygen pressure. X-ray diffraction, transmission electron microscopy, Raman scattering, and x-ray absorption spectroscopy confirmed the existence of the delafossite phase. Infrared reflectivity spectra determined a band edge at 1.15 eV, in agreement with the bulk delafossite data. Magnetization measurements on CuFeO{sub 2} films demonstrated a phase transition at T{sub C} ≈ 15 ± 1 K, which agrees with the first antiferromagnetic transition at 14 K in the bulk CuFeO{sub 2}. Low temperature magnetic phase is best described by commensurate, weak ferromagnetic spin ordering along the c-axis.

  1. Interfacial perpendicular magnetic anisotropy and damping parameter in ultra thin Co{sub 2}FeAl films

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Yishen [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Khodadadi, Behrouz; Schaefer, Sebastian; Mewes, Tim [Department of Physics and Astronomy, MINT Center, University of Alabama, Tuscaloosa, Alabama 35487 (United States); Lu, Jiwei [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Wolf, Stuart A. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2013-04-22

    B2-ordered Co{sub 2}FeAl films were synthesized using an ion beam deposition tool. A high degree of chemical ordering {approx}81.2% with a low damping parameter ({alpha}) less than 0.004 was obtained in a 50 nm thick film via rapid thermal annealing at 600 Degree-Sign C. The perpendicular magnetic anisotropy (PMA) was optimized in ultra thin Co{sub 2}FeAl films annealed at 350 Degree-Sign C without an external magnetic field. The reduced thickness and annealing temperature to achieve PMA introduced extrinsic factors thus increasing {alpha} significantly. However, the observed damping of Co{sub 2}FeAl films was still lower than that of Co{sub 60}Fe{sub 20}B{sub 20} films prepared at the same thickness and annealing temperature.

  2. Structural, electronic, and magnetic investigation of magnetic ordering in MBE-grown CrxSb2-xTe3 thin films

    Science.gov (United States)

    Collins-McIntyre, L. J.; Duffy, L. B.; Singh, A.; Steinke, N.-J.; Kinane, C. J.; Charlton, T. R.; Pushp, A.; Kellock, A. J.; Parkin, S. S. P.; Holmes, S. N.; Barnes, C. H. W.; van der Laan, G.; Langridge, S.; Hesjedal, T.

    2016-07-01

    We report the structural, electronic, and magnetic study of Cr-doped Sb2Te3 thin films grown by a two-step deposition process using molecular-beam epitaxy (MBE). The samples were investigated using a variety of complementary techniques, namely, x-ray diffraction (XRD), atomic force microscopy, SQUID magnetometry, magneto-transport, and polarized neutron reflectometry (PNR). It is found that the samples retain good crystalline order up to a doping level of x=0.42 (in Cr x Sb2-x Te3), above which degradation of the crystal structure is observed by XRD. Fits to the recorded XRD spectra indicate a general reduction in the c-axis lattice parameter as a function of doping, consistent with substitutional doping with an ion of smaller ionic radius. The samples show soft ferromagnetic behavior with the easy axis of magnetization being out-of-plane. The saturation magnetization is dependent on the doping level, and reaches from ˜2 μ_\\text{B} to almost 3 μ_\\text{B} per Cr ion. The transition temperature (T{c}) depends strongly on the Cr concentration and is found to increase with doping concentration. For the highest achievable doping level for phase-pure films of x=0.42 , a T{c} of 125 K was determined. Electric transport measurements find surface-dominated transport below ˜10 K. The magnetic properties extracted from anomalous Hall effect data are in excellent agreement with the magnetometry data. PNR studies indicate a uniform magnetization profile throughout the film, with no indication of enhanced magnetic order towards the sample surface.

  3. Structural and Magnetic Properties of Mn doped ZnO Thin Film Deposited by Pulsed Laser Deposition

    KAUST Repository

    Baras, Abdulaziz

    2011-07-01

    Diluted magnetic oxide (DMO) research is a growing field of interdisciplinary study like spintronic devices and medical imaging. A definite agreement among researchers concerning the origin of ferromagnetism in DMO has yet to be reached. This thesis presents a study on the structural and magnetic properties of DMO thin films. It attempts to contribute to the understanding of ferromagnetism (FM) origin in DMO. Pure ZnO and Mn doped ZnO thin films have been deposited by pulsed laser deposition (PLD) using different deposition conditions. This was conducted in order to correlate the change between structural and magnetic properties. Structural properties of the films were characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The superconducting quantum interference device (SQUID) was used to investigate the magnetic properties of these films. The structural characterizations showed that the quality of pure ZnO and Mn doped ZnO films increased as oxygen pressure (PO) increased during deposition. All samples were insulators. In Mn doped films, Mn concentration decreased as PO increased. The Mn doped ZnO samples were deposited at 600˚C and oxygen pressure from 50-500mTorr. All Mn doped films displayed room temperature ferromagnetism (RTFM). However, at 5 K a superparamagnetic (SPM) behavior was observed in these samples. This result was accounted for by the supposition that there were secondary phase(s) causing the superparamagnetic behavior. Our findings hope to strengthen existing research on DMO origins and suggest that secondary phases are the core components that suppress the ferromagnetism. Although RTFM and SPM at low temperature has been observed in other systems (e.g., Co doped ZnO), we are the first to report this behavior in Mn doped ZnO. Future research might extend the characterization and exploration of ferromagnetism in this system.

  4. In Situ Tuning of Magnetization and Magnetoresistance in Fe3O4 Thin Film Achieved with All-Solid-State Redox Device.

    Science.gov (United States)

    Tsuchiya, Takashi; Terabe, Kazuya; Ochi, Masanori; Higuchi, Tohru; Osada, Minoru; Yamashita, Yoshiyuki; Ueda, Shigenori; Aono, Masakazu

    2016-01-26

    An all-solid-state redox device composed of Fe3O4 thin film and Li(+) ion conducting solid electrolyte was fabricated for use in tuning magnetization and magnetoresistance (MR), which are key factors in the creation of high-density magnetic storage devices. Electrical conductivity, magnetization, and MR were reversibly tuned by Li(+) insertion and removal. Tuning of the various Fe3O4 thin film properties was achieved by donation of an electron to the Fe(3+) ions. This technique should lead to the development of spintronics devices based on the reversible switching of magnetization and spin polarization (P). It should also improve the performance of conventional magnetic random access memory (MRAM) devices in which the ON/OFF ratio has been limited to a small value due to a decrease in P near the tunnel barrier.

  5. Magnetic Field Dependence of the Critical Current in S-N Bilayer Thin Films

    Science.gov (United States)

    Sadleir, John E.; Lee, Sang-Jun; Smith, Stephen James; Bandler, Simon; Chervenak, James; Kilbourne, Caroline A.; Finkbeiner, Fred M.; Porter, Frederick S.; Kelley, Richard L.; Adams, Joseph S.; Eckart, Megan E.; Busch, Sarah; Porst, Jan-Patrick

    2013-01-01

    Here we investigate the effects a non-uniform applied magnetic field has on superconducting transition-edge sensors (TESs) critical current. This has implications on TES optimization. It has been shown that TESs resistive transition can be altered by magnetic fields. We have observed critical current rectification effects and explained these effects in terms of a magnetic self-field arising from asymmetric current injection into the sensor. Our TES physical model shows that this magnetic self-field can result in significantly degraded or improved TES performance. In order for this magnetically tuned TES strategy to reach its full potential we are investigating the effect a non-uniform applied magnetic field has on the critical current.

  6. Magnetostrictive iron gallium thin films grown onto antiferromagnetic manganese nitride: Structure and magnetism

    Science.gov (United States)

    Mandru, Andrada-Oana; Corbett, Joseph P.; Richard, Andrea L.; Gallagher, James; Meng, Keng-Yuan; Ingram, David C.; Yang, Fengyuan; Smith, Arthur R.

    2016-10-01

    We report structural and magnetic properties of magnetostrictive Fe100 -xGax (x ≈ 15) alloys when deposited onto antiferromagnetic manganese nitride and non-magnetic magnesium oxide substrates. From X-ray diffraction measurements, we find that the FeGa films are single crystalline. Scanning tunneling microscopy imaging reveals that the surface morphologies are dictated by the growth temperature, composition, and substrate. The magnetic properties can be tailored by the substrate, as found by magnetic force microscopy imaging and vibrating sample magnetometry measurements. In addition to pronounced tetragonal deformations, depositing FeGa onto manganese nitride leads to the formation of stripe-like magnetic domain patterns and to the appearance of perpendicular magnetic anisotropy.

  7. Phase-resolved detection of the spin Hall angle by optical ferromagnetic resonance in perpendicularly magnetized thin films

    Science.gov (United States)

    Capua, Amir; Wang, Tianyu; Yang, See-Hun; Rettner, Charles; Phung, Timothy; Parkin, Stuart S. P.

    2017-02-01

    The conversion of charge current to spin current by the spin Hall effect is of considerable current interest from both fundamental and technological perspectives. Measurement of the spin Hall angle, especially for atomically thin systems with large magnetic anisotropies, is not straightforward. Here we demonstrate a hybrid phase-resolved optical-electrical ferromagnetic resonance method that we show can robustly determine the spin Hall angle in heavy-metal/ferromagnet bilayer systems with large perpendicular magnetic anisotropy. We present an analytical model of the ferromagnetic resonance spectrum in the presence of the spin Hall effect, in which the spin Hall angle can be directly determined from the changes in the amplitude response as a function of the spin current that is generated from a dc charge current passing through the heavy-metal layer. Increased sensitivity to the spin current is achieved by operation under conditions for which the magnetic potential is shallowest at the "Smit point." Study of the phase response reveals that the spin Hall angle can be reliably extracted from a simplified measurement that does not require scanning over time or magnetic field but rather only on the dc current. The method is applied to the Pt-Co/Ni/Co system whose spin Hall angle was to date characterized only indirectly and that is especially relevant for spin-orbit torque devices.

  8. Structure, magnetic properties and electrical resistivity of Co2FeSi1-xGax Heusler alloy thin films

    Science.gov (United States)

    Ramudu, M.; Raja, M. Manivel; Chelvane, J. Arout; Kamat, S. V.

    2016-11-01

    The influence of Ga on the structural, magnetic and half-metallic properties of Co2FeSi1-xGax (0≤x≤1) thin films grown on Si (100) substrates using ultra high vacuum magnetron sputtering has been systematically investigated. The linear increase in cubic lattice parameter from 5.63 Å to 5.73 Å and the Curie temperature (TC) from 854 K to 941 K with x varying from 0 to 1 indicate the progressive substitution of Ga for Si. The coercivity (Hc) was found to decrease from 26 Oe (x=0) to 3 Oe (x=1) at room temperature and is attributed to the decrease in magnetic anisotropy. The magnetic hysteresis loops measured from 300-873 K revealed that the film where Ga completely replaces Si exhibit better stability in both saturation magnetization (Ms) and Hc with temperature. The increase in coercivity at higher temperatures is attributed to the film to substrate interaction. The measured Ms at 100 K decreases from 5.01 μB/f.u. (x=0) to 4.49 μB/f.u. (x=1) and follows the trend of Slater-Pauling rule. The indirect evidence of half-metallic nature is examined from the temperature dependent electrical resistivity measurements.

  9. A study on the thickness dependence of static and dynamic magnetic properties of Ni81Fe19 thin films

    Science.gov (United States)

    Kern, P. R.; da Silva, O. E.; de Siqueira, J. V.; Della Pace, R. D.; Rigue, J. N.; Carara, M.

    2016-12-01

    A set of Permalloy thin films with thicknesses ranging from 100 nm to 1000 nm have been investigated by in-plane hysteresis loops, magnetic torque, microwave permeability and X-ray diffraction measurements. The frequency evolution of the complex permeability was treated within the Debye relaxation model allowing the obtainment of the resonance frequency, resonance linewidth and the rotational component of the permeability at each applied field. The samples can be separated in three groups according their magnetic properties. Samples with thickness until 150 nm present magnetic properties typical of a system with a well defined in-plane uniaxial anisotropy and just one resonance frequency in the high frequency permeability spectra. Samples with thicknesses above 300 nm present magnetization loops almost isotropic in-plane and two resonance frequencies in the permeability spectra. The samples at the intermediate thickness range present some characteristic from thinner and other of the thicker group. Ferromagnetic resonance and torque measurements have detected the presence of a small uniaxial anisotropy even in the thicker group of samples. The multiple ferromagnetic resonances in the permeability spectra present in the thicker group of samples were treated as non-interacting magnetic systems. These characteristics were attributed to the appearance of stripe domains together with a rotatable anisotropy, due to an out-of-plane magnetization component. The relaxation mechanisms which give rise to the resonance linewidth were discussed considering two possible sources, Gilbert damping and anisotropy dispersion. While the Gilbert damping was almost the same for all samples it was verified the anisotropy dispersion increase with the thickness.

  10. Distinguishing Magnetic Behavior on the Slater-Pauling Curve applied to nanoscale thin films.

    Science.gov (United States)

    Podolak, K. R.; Birke, M. G.; Janke-Gilman, N.; Willis, R. F.

    2006-03-01

    The Slater-Pauling curve is a plot of the stoichiometric mean saturation magnetization per atom as a function of the electron filling of the d-bands in the transition metals and their alloys. When the elemental magnetic moments are aligned, the volcano-shape curve plots the variation of the mean magnetic moment. It has been predicted that a narrowing of the d-bands in nanostructured magnetic materials will influence both the magnitude of the magnetic moments as well as the overall magnetic alignment through increased spin-orbit coupling [1]. In this paper, we report dichroism in the core-level x-ray photoemission spectra of the elements which reveals and distinguishes the changing magnitudes of the magnetic moments and the changing alignment of these moments with changing composition. The 3p core-level spectral densities of multiplet spin-ordered states show a width W proportional to the local Zeeman splitting of levels, and a magnetic dichroism amplitude A sensitive to the non-local magnetic order (anisotropy). In nanoscale epitaxial layers, small deviations from the bulk Slater-Pauling curve are observed due to enhanced moments due to d-band narrowing [2]. It is predicted that a plot of the spectral parameters W, A will show a different dependence of temperature approaching Tc, the critical ordering temperature. [1] S. Handschuh & S. Blügel, Solid State Communications. 105, 633 (1998). [2] R.F. Willis & N. Janke-Gilman, Europhysics Letters. 69, 411 (2005).

  11. Uniaxial magnetic anisotropy induced low field anomalous anisotropic magnetoresistance in manganite thin films

    Directory of Open Access Journals (Sweden)

    Zhaoliang Liao

    2014-09-01

    Full Text Available La2/3Sr1/3MnO3 films with uniaxial magnetic anisotropy were coherently grown on NdGaO3 (110 substrates. The uniaxial anisotropy has strong effect on magnetoresistance (MR. A positive MR was observed when the current is along magnetic easy axis under the current-field perpendicular geometry. In contrast, no positive MR is observed when current is along the magnetic hard axis regardless of the field direction. Our analysis indicates that the anomalous anisotropic MR effect arises from the uniaxial magnetic anisotropy caused stripe domains which contribute to strong anisotropic domain wall resistivity.

  12. Tailoring out-of-plane magnetic properties of pulsed laser deposited FePt thin films by changing laser energy fluence

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ying; Tan, T.L.; Tan, K.S.; Lee, P. [NSSE, NIE, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Liu, Hai; Yadian, Boluo; Hu, Ge; Huang, Yizhong; Ramanujan, R.V. [School of Material Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Rawat, R.S., E-mail: rajdeep.rawat@nie.edu.sg [NSSE, NIE, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

    2014-10-01

    Highlights: • Laser energy fluence (LEF) effect on composition, microstructure and magnetism. • Enhancing out-of-plane magnetic properties by tailoring LEF on target surface. • Higher LEF results in more energetic plasma species causing vacancy defects. • Formation of vacancy defect in FePt thin films leads to improved magnetic properties. • Best out-of-plane magnetic properties are achieved with medium LEF. - Abstract: Magnetic properties of pulsed laser deposited (PLD) FePt thin films are investigated at three different laser energy fluences of 51, 136 and 182 J/cm{sup 2}. Deposition at lower laser energy fluence (51 J/cm{sup 2}) yields softer out-of-plane coercivity (≤0.4 kG), whereas deposition at higher laser energy fluence (136 and 182 J/cm{sup 2}) results in harder out-of-plane coercivity (≥5.0 kG). The improved coercivity is found to be attributed to the formation of vacancy defects in thin films, which is indicated by stress change from tensile to compressive form with increasing laser energy fluence. Maximum out-of-plane saturated magnetization of 615 emu/cm{sup 3} and remanent squareness ratio of 0.88 are achieved for 16 nm thick FePt thin films deposited at moderate laser energy fluence of 136 J/cm{sup 2}, making them suitable for high density perpendicular data storage applications.

  13. Structure and magnetic properties of polycrystalline iron-platium and cobalt-platinum thin films for high density recording media

    Science.gov (United States)

    Jeong, Sangki

    2002-09-01

    The goal of this project was to investigate and increase the feasibility of use of FePt and CoPt polycrystalline thin films as high-density recording media, with a focus on targeting perpendicular recording. Understanding the atomic ordering process, developing the proper texture and small grains, lowering the processing temperature and optimizing magnetic properties were the main subjects of this thesis work. In this thesis, nano-structured polycrystalline high anisotropy thin films have been fabricated and characterized. Polycrystalline CoPt and FePt films exhibit perpendicular anisotropy after an annealing process only when their thickness is less than 5 nm. High temperature annealing is still required to obtain an atomically ordered phase with nearly full ordering. The ordering phase transformation is a discontinuous transformation that yields an inhomogeneous microstructure where significant amount of FCC phase remains, unless a long time annealing process is performed. To lower the atomic ordering temperature, an in-situ ordering process has been performed and the various underlayer structures with an MgO seed layer, have been deposited and investigated. Thin films with thicknesses below 10 nm exhibit perpendicular anisotropy with an average grain size in the range of 10--15 nm in this film. FePt [001] textured films using Pt/Ag seeding layer exhibit lower annealing temperature than FePt/MgO films, while other Ag or Cr seedlayers do not produce faster ordering kinetics. Based on the detailed analysis of nanostructure of FePt thin films, it has been learned that FCC disordered nanoclusters remains in the ordered grains. Detailed observation of magnetic properties and nanostructure by HRTEM suggests that, though a thermally activated component of the switching is observed, the low value of coercivity can be attributed predominantly to reversal processes associated with defect related domain nucleation. We postulate that the nucleation occurs in less ordered

  14. Influence of defects on the structural and magnetic properties of multifunctional La2NiMnO6 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Guo, HZ [University of Alabama, Tuscaloosa; Burgess, J [University of Alabama, Tuscaloosa; Ada, E [University of Alabama, Tuscaloosa; Street, S [University of Alabama, Tuscaloosa; Gupta, A. [University of Alabama, Tuscaloosa; Iliev, M N [University of Houston, Houston; Kellock, A J [IBM Corporation, Almaden Research Center; Magen Dominguez, Cesar [ORNL; Varela del Arco, Maria [ORNL; Pennycook, Stephen J [ORNL

    2008-01-01

    Thin films of the double perovskite La2NiMnO6 (LNMO) have been grown on various lattice-matched substrates (SrTiO3, LaAlO3, NdGaO3 and MgO) by pulsed laser deposition under varying oxygen background pressure (25 - 800 mTorr). The out-of-plane lattice constant of the LNMO film initially decreases with increasing pressure, likely caused by a reduction in the defect concentration and improved structural ordering, before leveling off at higher pressures. Scanning transmission electron microscopy results show that the films are epitaxial, and the interface is sharp and coherent. While very few defects are observed by STEM in a film grown at high oxygen pressure (800 mTorr), a film grown at a lower pressure (100 mTorr) shows the formation of defects that extend throughout the thickness except for a very thin layer near the interface. The Raman spectra of the films are dominated by two broad peaks at around 540 cm-1 and 685 cm-1, which are assigned to the antisymmetric stretching (AS) and symmetric stretching (S) modes of MnO6 and NiO6 octahedra, respectively. The Raman peaks of the LNMO thin films grown in 800 mTorr background O2 are blue shifted in comparison to those of LNMO bulk, and the shift increases with decreasing film thickness, indicating the increased influence of strain. The critical thickness for strain relaxation as determined from the Raman spectra is between 40 - 80 nm. The strain is observed to have a negligible influence on the magnetic properties for films grown at high oxygen pressures. However, films grown at low pressures exhibit degraded magnetic properties, which can be attributed to a combination of B-site cation disorder and an increase in the concentration of Mn3+ and Ni3+ Jahn-Teller ions caused by oxygen defects. With increasing oxygen pressure during growth, the paramagnetic-ferromagnetic transition temperature (~280 K) gets sharper and the saturation magnetization at low temperatures is enhanced. Based on electron energy loss spectroscopy

  15. Correcting and coating thin walled X-ray Optics via a combination of controlled film deposition and magnetic smart materials

    Science.gov (United States)

    Ulmer, Melville

    The project goal is to demonstrate that thin walled (price. Since the desired surface area for the next generation X-ray telescope is >10x that of Chandra, the >10x requirement is then for >200 m^2 of surface area with a surface finish of better than 0.5 nm. Therefore, replication of some sort is called for. Because no replication technology has been shown to achieve ≤1" angular resolution, post fabrication figure corrections are likely going to be necessary. Some have proposed to do this in orbit and others prelaunch including us. Our prelaunch approach is to apply in-plane stresses to the thin walled mirror shells via a magnetic field. The field will be held in by some magnetically hard material such as NiCo. By use of a so called magnetic smart material (MSM) such as Terfenol-D, we already shown that strong enough stresses can be generated. Preliminary work has also shown that the magnetic field can be held in well enough to apply the figure correcting stresses pre-launch. What we call "set-it and forget-it." However, what is unique about our approach is that at the cost of complexity and some areal coverage, our concept will also accommodate in-orbit adjustments. Furthermore, to the best of our knowledge ours is one of two known stress modification processes that are bi-axial. Our plan is first to validate set-it and forget-it first on cantilevers and then to expand this to working on 5 cm x 5 cm pieces. We will work both with NiCo and glass or Si coated with Terfenol-D. Except for the NiCo, substrates we will also coat the samples with NiCo in order to have a film that will hold in the magnetic field. As part of the coating process, we will control the stress of the film by varying the voltage bias while coating. The bias stress control can be used to apply films with minimal stress such as Terfenol-D and X-ray reflecting coatings such as Ir. Ir is a highly desirable coating for soft X-ray astronomy mirrors that can have significant built in stress unless

  16. Structural and magnetic properties of Ni78Fe22 thin films sandwiched between low-softening-point glasses and application in spin devices

    Science.gov (United States)

    Misawa, Takahiro; Mori, Sumito; Komine, Takashi; Fujioka, Masaya; Nishii, Junji; Kaiju, Hideo

    2016-12-01

    We investigate the structural and magnetic properties of Ni78Fe22 thin films sandwiched between low-softening-point (LSP) glasses, which can be used in spin quantum cross (SQC) devices utilizing stray magnetic fields generated from magnetic thin-film edges. We also calculate the stray magnetic field generated between the two edges of Ni78Fe22 thin-film electrodes in SQC devices and discuss the applicability to spin-filter devices. Using the established fabrication technique, we successfully demonstrate the formation of LSP-glass/Ni78Fe22/LSP-glass structures with smooth and clear interfaces. The coercivity of the Ni78Fe22 thin films is enhanced from 0.9 to 103 Oe by increasing the applied pressure from 0 to 1.0 MPa in the thermal pressing process. According to the random anisotropy model, the enhancement of the coercivity is attributed to the increase in the crystal grain size. The stray magnetic field is also uniformly generated from the Ni78Fe22 thin-film edge in the direction perpendicular to the cross section of the LSP-glass/Ni78Fe22/LSP-glass structures. Theoretical calculation reveals that a high stray field of approximately 5 kOe is generated when the distance between two edges of the Ni78Fe22 thin-film electrodes is less than 5 nm and the thickness of Ni78Fe22 is greater than 20 nm. These experimental and calculation results indicate that Ni78Fe22 thin films sandwiched between LSP glasses are useful as electrodes for SQC devices, serving as spin-filter devices.

  17. Effects of strain on the magnetic and transport properties of the epitaxial La0.5Ca0.5MnO3 thin films

    Science.gov (United States)

    Zarifi, M.; Kameli, P.; Ehsani, M. H.; Ahmadvand, H.; Salamati, H.

    2016-12-01

    The epitaxial strain can considerably modify the physical properties of thin films compared to the bulk. This paper reports the effects of substrate-induced strain on La0.5Ca0.5MnO3 (LCMO) thin films, grown on (100) SrTiO3 (STO) and LaAlO3 (LAO) substrates by pulsed laser deposition technique. Transport and magnetic properties were found to be strongly dependent on strain type. It is also shown that compressive (tensile) strain leads to the increase (decrease) in the magnetization of the films. Moreover, it was observed that all LCMO films deposited on both LAO and STO substrates behave as an insulator, but LCMO/LAO thin films with compressive strain have lower resistivity than LCMO/STO thin films with tensile strain. Applying magnetic field to LCMO/STO thin films with thickness of 25 and 50 nm leads to very small change in the resistivity, while the effects of magnetic field on the sample with thickness of 125 nm leads to an insulator-metal transition. For LCMO/LAO thin films, the magnetic field has a strong impact on the resistivity of samples. The results show that the magnetoresistance (MR) is enhanced by increasing film thickness for LCMO/LAO samples, due to the relatively stronger phase separation. For LCMO/STO thin films MR is drastically decreased by reduction of film thickness, which is attributed to the enhancement of the charge-orbital order (CO-O) accompanying the complex spin order (the so-called CE type). The changes of the antiferromagnetic structure from the CE to C type and the enhancement of the CE type could be attributed to the in-plane compressive and tensile strain, respectively.

  18. The influence of the textural development on magnetic properties in Co-Cr thin films

    NARCIS (Netherlands)

    Li, Cheng-Zhang; Lodder, J.C.; Szpunar, J.A.

    1994-01-01

    Two series Co81Cr19 films (5-980 nm) were chosen to investigate the influence of textural development on magnetic properties. It was demonstrated that both the texture and the magnetic properties strongly depend on the film thickness. In the thickness range from 12 to 980 nm, the coercivity Hc and t

  19. Enhancement of perpendicular magnetic anisotropy by compressive strain in alternately layered FeNi thin films.

    Science.gov (United States)

    Sakamaki, M; Amemiya, K

    2014-04-23

    The effect of the lattice strain on magnetic anisotropy of alternately layered FeNi ultrathin films grown on a substrate, Cu(tCu = 0-70 ML)/Ni(48)Cu(52)(124 ML)/Cu(0 0 1) single crystal, is systematically studied by means of in situ x-ray magnetic circular dichroism (XMCD) and reflection high-energy electron diffraction (RHEED) analyses. To investigate the magnetic anisotropy of the FeNi layer itself, a non-magnetic substrate is adopted. From the RHEED analysis, the in-plane lattice constant, ain, of the substrate is found to shrink by 0.8% and 0.5% at tCu = 0 and 10 ML as compared to that of bulk Cu, respectively. Fe L-edge XMCD analysis is performed for n ML FeNi films grown on various ain, and perpendicular magnetic anisotropy (PMA) is observed at n = 3 and 5, whereas the film with n = 7 shows in-plane magnetic anisotropy. Moreover, it is found that PMA is enhanced with decreasing ain, in the case where a Cu spacer layer is inserted. We suppose that magnetic anisotropy in the FeNi films is mainly carried by Fe, and the delocalization of the in-plane orbitals near the Fermi level increases the perpendicular orbital magnetic moment, which leads to the enhancement of PMA.

  20. Ferrofluid thin films as optical gaussmeters proposed for field and magnetic moment sensing

    Indian Academy of Sciences (India)

    Swapna S Nair; S Rajesh; V S Abraham; M R Anantharaman

    2011-04-01

    Ferrofluids belonging to the series, NiFe1−Fe2O4 and ZnFe1−Fe2O4, were synthesized using cold co-precipitation. Liquid films of these ferrofluids were prepared by encapsulating the ferrofluids in between two optically smooth and ultrasonically cleaned glass plates. Magnetic field induced laser transmission through these ferrofluid films has been investigated. Magnetic field values can be calibrated in terms of output laser power in the low field region in which the variation is linear. This set up can be used as a cheap optical gaussmeter in the low field regime. Using the same set-up, the saturation magnetization of the sample used can also be calculated with a sample that is pre-characterized. Hence both magnetization of the sample, as well as applied magnetic field can be sensed and calculated with a precalibrated sample.