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Sample records for crystal fe films

  1. Magnetostrictive behaviors of Fe-Al(001 single-crystal films under rotating magnetic fields

    Directory of Open Access Journals (Sweden)

    Tetsuroh Kawai

    2016-05-01

    Full Text Available Magnetostrictive behaviors of Fe100−x − Alx(x = 0 − 30 at.%(001 single-crystal films under rotating magnetic fields are investigated along the two different crystallographic orientations, [100] and [110]. The behaviors of Fe and Fe90Al10 films show bath-tub like waveform along [100], easy magnetization axis, and triangular waveform along [110], hard magnetization axis, with respect to their four-fold magnetic anisotropy. On the other hand, the behaviors of Fe80Al20 film are different from those of Fe or Fe90Al10 film. The output of the film along [100] shows a strong magnetic field dependence. The Fe70Al30 film shows similar magnetostrictive behaviors along both [100] and [110] reflecting its magnetic properties, which are almost same for the both directions. The growth of ordered phase (B2 in Fe80Al20 and Fe70Al30 films is considered to have affected their magnetostrictive behaviors. The Al content dependence on λ100 and λ111 values shows similar tendency to that reported for the bulk samples but the values are slightly different. The Fe90Al10(001 single-crystal film shows a large magnetostriction along [100] under a very small magnetic field of 0.02 kOe, which is comparable to the saturated one, and changes the value abruptly in relation to the angle of applied magnetic field.

  2. Crystallographic and magnetostriction properties of Fe and FeB-alloy thin films formed on MgO(100 single-crystal substrates

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    Ohtake M.

    2013-01-01

    Full Text Available Fe(100bcc single-crystal film, Fe-B amorphous film, and Fe-B film consisting of a mixture of epitaxial bcc(100 crystal and amorphous are prepared on MgO(100 single-crystal substrates. The influence of crystallographic property on the magnetostriction behavior under rotating magnetic fields is investigated. The output waveform of magnetostriction is sinusoidal for the amorphous film, whereas that of single-crystal film shows a triangle shape. 90° magnetic domain walls are observed for the single-crystal Fe film and the film shows a four-fold symmetry in in-plane magnetic anisotropy. The observation of triangle waveforms is related to the domain wall motion in magnetically unsaturated Fe(100bcc film under rotating magnetic fields. A distortion from triangle wave is observed for the Fe-B film consisting of a mixture of bcc-crystal and amorphous. The magnetostriction behavior is influenced by the magnetization structure.

  3. Anomalous Hall effects in pseudo-single-crystal γ'-Fe4N thin films

    Science.gov (United States)

    Kabara, Kazuki; Tsunoda, Masakiyo; Kokado, Satoshi

    2016-05-01

    The anomalous Hall effects (AHE) were investigated at various temperatures for the pseudo-single-crystal Fe4N films, deposited on MgO substrates with changing the degree of order (S) of the nitrogen site. Both the anomalous Hall resistivity and the longitudinal resistivity simply decrease with lowering temperature for all the specimens. The AHE of the Fe4N films is presumed to arise from an intrinsic mechanism because of the relationship between the anomalous Hall resistivity and longitudinal resistivity. The anomalous Hall conductivity, σAH, exhibits a specific behavior at low temperature. In the case of the film with S = 0.93, the σAH drastically drops below 50 K, while it simply increases with lowering temperature in the range of 50-300 K. This low-temperature anomaly decays with decreasing S of the film and nearly vanishes in the films with low S. The threshold temperature and the dependence on S of the low-temperature anomaly of the σAH well correspond to those of the anisotropic magnetoresistance effects in the Fe4N films, reported in the literatures. From these results, it is suggested that the low-temperature anomaly of the σAH originates from the crystal field effect which reflects the structural transformation from a cubic to a tetragonal symmetry below 50 K and provides a modulation of the orbital angular momentum of the 3d orbitals at the Fermi level.

  4. Single crystal Fe1-xGax thin films for monolithic microwave devices

    Science.gov (United States)

    Kuanr, Bijoy K.; Camley, R. E.; Celinski, Z.; McClure, Adam; Idzerda, Yves

    2014-05-01

    Modern, high frequency, microwave devices for communications technologies can be made with thin ferromagnetic films with narrow microwave resonance linewidths. Recently, there has been interest in magnetostrictive materials where the material constants can change substantially with stresses and applied magnetic fields. We report the development of single crystal thin (20 nm thick) magnetostrictive films of Fe1-xGax (x = 0.20 FeGa(A), 0.23 FeGa(B), 0.28 FeGa(C) on GaAs(001) substrates and on their use in prototype microwave devices. These Galfenol films have a narrower linewidth than any previously reported similar thin films. We fabricate and characterize novel microstrip-based monolithic microwave devices using Galfenol thin films as an active element. We find a number of important features: (1) There is a large absorption (up to 30 dB/cm) at the resonance frequency. (2) The linewidth of the device is narrow ˜1.5 GHz. (3) The saturation magnetization of the samples decreases with the increase in Ga contents. (4) The cubic anisotropy is close to zero (˜0.06 kOe for FeGa(A)) and becomes negative for higher concentration of Ga content in the samples, and (5) the damping increases with increase in Ga concentration.

  5. Transverse anisotropic magnetoresistance effects in pseudo-single-crystal γ'-Fe4N thin films

    Science.gov (United States)

    Kabara, Kazuki; Tsunoda, Masakiyo; Kokado, Satoshi

    2016-05-01

    Transverse anisotropic magnetoresistance (AMR) effects, for which magnetization is rotated in an orthogonal plane to the current direction, were investigated at various temperatures, in order to clarify the structural transformation from a cubic to a tetragonal symmetry in a pseudo-single-crystal Fe4N film, which is predicted from the usual in-plane AMR measurements by the theory taking into account the spin-orbit interaction and crystal field splitting of 3d bands. According to a phenomenological theory of AMR, which derives only from the crystal symmetry, a cos 2θ component ( C2 tr ) exists in transverse AMR curves for a tetragonal system but does not for a cubic system. In the Fe4N film, the C2 tr shows a positive small value (0.12%) from 300 K to 50 K. However, the C2 t r increases to negative value below 50 K and reaches to -2% at 5 K. The drastic increasing of the C2 tr demonstrates the structural transformation from a cubic to a tetragonal symmetry below 50 K in the Fe4N film. In addition, the out-of-plane and in-plane lattice constants (c and a) were precisely determined with X-ray diffraction at room temperature using the Nelson-Riely function. As a result, the positive small C2 t r above 50 K is attributed to a slightly distorted Fe4N lattice (c/a = 1.002).

  6. Ferrimagnetic ordering of single crystal Fe1-xGax thin films

    Energy Technology Data Exchange (ETDEWEB)

    McClure, A.; Arenholz, E.; Idzerda, Y. U.

    2009-10-19

    Molecular beam epitaxy was used to deposit body centered cubic single crystal Fe{sub 1-x}Ga{sub x} thin films on MgO(001) and ZnSe/GaAs(001) substrates well beyond the bulk stability concentration of about 28%. The crystal quality of the substrate surface and each deposited layer was monitored in situ by reflection high energy electron diffraction. The magnetization of the samples as a function of Ga is found to decrease more rapidly than a simple dilution effect, and element-specific x-ray magnetic circular dichroism ascribes this trend to a decrease in the Fe moment and an induced moment in the Ga that is antialigned to the Fe moment.

  7. Silole-infiltrated photonic crystal films as effective fluorescence sensor for Fe3+ and Hg2+.

    Science.gov (United States)

    Zhang, Yuqi; Li, Xiangdong; Gao, Loujun; Qiu, Jianhua; Heng, Liping; Tang, Ben Zhong; Jiang, Lei

    2014-02-24

    We develop a highly effective silole-infiltrated photonic crystal (PC) film fluorescence sensor with high sensitivity, good selectivity and excellent reproducibility for Fe(3+) and Hg(2+) ions. Hexaphenylsilole (HPS) infiltrated PCs show amplified fluorescence due to the slow photon effect of PC because the emission wavelength of HPS is at the blue band edge of the selected PC's stopband. The fluorescence can be quenched significantly by Fe(3+)/Hg(2+) ions owing to electron transfer between HPS and metal ions. The amplified fluorescence enhances the sensitivity of detection, with a detection limit of 5 nM for Fe(3+)/Hg(2+) ions. The sensor is negligibly responsive to other metal ions and can easily be reproduced by rinsing with pure water due to the special surface wettability of PC. As a result, a highly effective Fe(3+)/Hg(2+) ions sensor based on HPS-infiltrated PC film has been achieved, which will be important for effective and practical detection of heavy metal ions.

  8. Ultrafast carrier dynamics and radiative recombination in multiferroic BiFeO3 single crystals and thin films

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    Taylor A. J.

    2013-03-01

    Full Text Available We report a detailed comparison of ultrafast carrier dynamics in single crystals and thin films of multiferroic BiFeO3 (BFO. Using degenerate femtosecond optical pump-probe spectroscopy, we find that the observed dynamics are qualitatively similar in both samples. After photoexcitation, electrons relax to the conduction band minimum through electron-phonon coupling, with subsequent carrier relaxation proceeding via various recombination pathways that extend to a nanosecond timescale. Subtle differences observed in our measurements indicate that BFO films have a higher band gap than single crystals. Overall, our results demonstrate that carrier relaxation in BFO is analogous to that in bulk semiconductors.

  9. Transverse anisotropic magnetoresistance effects in pseudo-single-crystal γ′-Fe4N thin films

    Directory of Open Access Journals (Sweden)

    Kazuki Kabara

    2016-05-01

    Full Text Available Transverse anisotropic magnetoresistance (AMR effects, for which magnetization is rotated in an orthogonal plane to the current direction, were investigated at various temperatures, in order to clarify the structural transformation from a cubic to a tetragonal symmetry in a pseudo-single-crystal Fe4N film, which is predicted from the usual in-plane AMR measurements by the theory taking into account the spin-orbit interaction and crystal field splitting of 3d bands. According to a phenomenological theory of AMR, which derives only from the crystal symmetry, a cos 2θ component ( C 2 tr exists in transverse AMR curves for a tetragonal system but does not for a cubic system. In the Fe4N film, the C 2 tr shows a positive small value (0.12% from 300 K to 50 K. However, the C 2 t r increases to negative value below 50 K and reaches to -2% at 5 K. The drastic increasing of the C 2 tr demonstrates the structural transformation from a cubic to a tetragonal symmetry below 50 K in the Fe4N film. In addition, the out-of-plane and in-plane lattice constants (c and a were precisely determined with X-ray diffraction at room temperature using the Nelson-Riely function. As a result, the positive small C 2 t r above 50 K is attributed to a slightly distorted Fe4N lattice (c/a = 1.002.

  10. L10 ordered phase formation in FePt, FePd, CoPt, and CoPd alloy thin films epitaxially grown on MgO(001) single-crystal substrates

    Science.gov (United States)

    Ohtake, Mitsuru; Ouchi, Shouhei; Kirino, Fumiyoshi; Futamoto, Masaaki

    2012-04-01

    The FePt, FePd, CoPt, and CoPd epitaxial thin films are prepared on MgO(001) single-crystal substrates by ultrahigh vacuum RF magnetron sputtering. The effects of the magnetic material and the substrate temperature on the film growth, the film structure, and the magnetic properties are investigated. The L10 ordered phase formation is observed for FePt, FePd, and CoPt films prepared at temperatures higher than 200, 400, and 600 °C, respectively, whereas that is not recognized for CoPd films. The L10-FePd(001) single-crystal films with the c-axis normal to the substrate surface are formed, whereas the FePt and CoPt epitaxial films include L10(100) crystals whose c-axis is parallel to the substrate surface, in addition to the L10(001) crystals. Upon increasing the substrate temperature, the ordering degree increases. A higher ordering parameter is observed in the order of FePd > FePt > CoPt. The magnetic properties are influenced by the crystal structure, the crystallographic orientation of the L10 crystal, and the ordering degree.

  11. Magnetostriction of fcc(110 single-crystal films of Ni-Fe, Ni, and Co under rotating magnetic fields

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    Ohtani Taiki

    2014-07-01

    Full Text Available Ni-Fe, Ni, and Co(110 single-crystal films with uniaxial magnetic anisotropies are prepared on MgO(110 substrates by radio-frequency magnetron sputtering. The magnetostriction behavior under rotating magnetic fields is investigated. The Ni-Fe film shows waveforms consisting of a mixture of sinusoidal and triangular shapes under fields lower than 200 Oe. The peak of sinusoidal shape is observed when the field is applied along the easy magnetization axis, whereas that of triangular shape appears when the field is applied along the hard axis. With increasing the field from 200 to 300 Oe, the waveform changes to a usual sinusoidal shape. The waveform variation is related to the difference between the directions of uniaxial magnetic anisotropy and magnetization of magnetically unsaturated film. Waveforms consisting of sinusoidal and triangular shapes are also observed for the Ni and the Co films under low rotating fields. The threshold magnetic field where the shape changes to sinusoidal increases in the order of Ni-Fe < Ni < Co. The waveform is influenced by the symmetry and the strength of magnetic anisotropy.

  12. Thickness dependence of the conductivity of thin films (La,Sr)FeO3 deposited on MgO single crystal

    DEFF Research Database (Denmark)

    Mosleh, Majid; Pryds, Nini; Hendriksen, Peter Vang

    2007-01-01

    Thin films of La0.6Sr0.4FeO3-delta of different thicknesses have been deposited on single crystal MgO substrate by pulsed laser deposition (PLD). The deposited films are characterized by XRD before and after annealing, by scanning electron microscopy (SEM) for morphological characterization...

  13. Structural, electro-magnetic, and optical properties of Ba(Fe,Ni)2As2 single-crystal thin film

    Science.gov (United States)

    Yoon, Sejun; Seo, Yu-Seong; Lee, Seokbae; Weiss, Jeremy D.; Jiang, Jianyi; Oh, MyeongJun; Lee, Jongmin; Seo, Sehun; Jo, Youn Jung; Hellstrom, Eric E.; Hwang, Jungseek; Lee, Sanghan

    2017-03-01

    We investigated the superconducting transition temperature (T c), critical current density (J c) and optical properties of optimally doped Ba(Fe0.95Ni0.05)2As2 (Ni-Ba122) single-crystalline epitaxial thin films grown by pulsed laser deposition for the first time. The T c at zero resistivity was about 20.5 K and the J c at self-field and 4.2 K was 2.8 MA cm-2 calculated by the Bean model. The superconducting properties such as T c and J c of thin films are comparable to those of bulk single-crystal samples. The superfluid plasma frequency (λ p,S) of Ni-Ba122 thin film is ˜7033 cm-1 obtained by optical spectroscopic technique. Based on this plasma frequency, we obtained the London penetration depth (λ L), ˜226 nm at 8 K, which is comparable to those of optimally Co- and K-doped BaFe2As2 single crystals.

  14. Interface between metallic film from Fe-Ni-C system and HPHT as-grown diamond single crystal

    Institute of Scientific and Technical Information of China (English)

    许斌; 李木森; 尹龙卫; 刘玉先; 崔建军; 宫建红

    2003-01-01

    Microstructures of surface layer (near diamond) of the metallic film from Fe-Ni-C system are composed of (Fe,Ni)3C, (Fe,Ni)23C6 and γ-(Fe,Ni), from which it can be assumed that graphite isn't directly catalyzed into diamond through the film and there exists a transition phase (Fe,Ni)3C that can decompose into diamond structure. AFM morphologies on the film/diamond interface are traces preserved after carbon groups moving from the film to diamond. The morphologies on the as-grown diamond are similar to those on corresponding films, being spherical on (100) face and sawtooth-like steps on (111) face. Diamond growth rates and temperature gradients in boundary layer of the molten film at HPHT result in morphology differences.

  15. A study on the electrodeposition of NiFe alloy thin films using chronocoulometry and electrochemical quartz crystal microgravimetry

    CERN Document Server

    Myung, N S

    2001-01-01

    Ni, Fe and NiFe alloy thin films were electrodeposited at a polycrystalline Au surface using a range of electrolytes and potentials. Coulometry and EQCM were used for real-time monitoring of electroplating efficiency of the Ni and Fe. The plating efficiency of NiFe alloy thin films was computed with the aid of ICP spectrometry. In general, plating efficiency increased to a steady value with deposition time. Plating efficiency of Fe was lower than that of Ni at -0.85 and -1.0 V but the efficiency approached to the similar plateau value to that of Ni at more negative potentials. The films with higher content of Fe showed different stripping behavior from the ones with higher content of Ni. Finally, compositional data and real-time plating efficiency are presented for films electrodeposited using a range of electrolytes and potentials.

  16. Magnetic properties of epitaxial Fe{sub 3}O{sub 4} films with various crystal orientations and tunnel magnetoresistance effect at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nagahama, Taro, E-mail: nagahama@eng.hokudai.ac.jp; Matsuda, Yuya; Tate, Kazuya; Kawai, Tomohiro; Takahashi, Nozomi; Hiratani, Shungo; Watanabe, Yusuke; Yanase, Takashi; Shimada, Toshihiro [Graduate School of Engineering, Hokkaido University, Kita13 Nishi8, Kitak-ku, Sapporo 060-8628 (Japan)

    2014-09-08

    Fe{sub 3}O{sub 4} is a ferrimagnetic spinel ferrite that exhibits electric conductivity at room temperature (RT). Although the material has been predicted to be a half metal according to ab-initio calculations, magnetic tunnel junctions (MTJs) with Fe{sub 3}O{sub 4} electrodes have demonstrated a small tunnel magnetoresistance (TMR) effect. Not even the sign of the tunnel magnetoresistance ratio has been experimentally established. Here, we report on the magnetic properties of epitaxial Fe{sub 3}O{sub 4} films with various crystal orientations. The films exhibited apparent crystal orientation dependence on hysteresis curves. In particular, Fe{sub 3}O{sub 4}(110) films exhibited in-plane uniaxial magnetic anisotropy. With respect to the squareness of hysteresis, Fe{sub 3}O{sub 4} (111) demonstrated the largest squareness. Furthermore, we fabricated MTJs with Fe{sub 3}O{sub 4}(110) electrodes and obtained a TMR effect of −12% at RT. The negative TMR ratio corresponded to the negative spin polarization of Fe{sub 3}O{sub 4} predicted from band calculations.

  17. Epitaxially stabilized TiN/(Ti,Fe,Co)N multilayer thin films in (pseudo-)fcc crystal structure by sequential magnetron sputter deposition

    Energy Technology Data Exchange (ETDEWEB)

    Klever, C; Seemann, K; Stueber, M; Ulrich, S; Leiste, H [Karlsruhe Institute of Technology (KIT), Institute for Materials Research I, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Brunken, H; Ludwig, A, E-mail: christian.klever@kit.ed [Ruhr-University Bochum, Institute of Materials, Universitaetsstr. 150, 44780 Bochum (Germany)

    2010-10-06

    Multilayer thin films were grown by non-reactive sequential magnetron sputter deposition from ceramic TiN and metallic FeCo targets addressing a combination of wear resistance and sensoric functionality. Coatings with bilayer period values ranging from 449 nm down to 2.6 nm were grown with the total amount of either material maintained constant. The multilayer thin films were post-annealed ex situ at 600 {sup 0}C for 60 min in vacuum. X-ray diffraction results imply the multilayer thin films undergo significant changes in their crystalline structure when the bilayer period is decreased. Using high-resolution transmission electron microscopy as well as selected-area electron diffraction it is shown that in the case of multilayer thin films with bilayer periods of several tens of nanometres and higher, FeCo layers and TiN layers in their respective common CsCl- and NaCl-type crystal structures alternate. In contrast, in the multilayer thin films with bilayer periods of only a few nanometres, grain growth across the interfaces between the individual layers takes place and a strongly textured microstructure is formed which features columns in (pseudo-)fcc crystal structure grown in heteroepitaxial growth mode. It is suggested that the experimental findings imply the latter multilayer thin films to be alternately composed of TiN layers and (Ti,Fe,Co)N solid solution layers which have been formed by a solid-state reaction during the deposition process. As a consequence, heteroepitaxially stabilized columnar grains in strongly textured (pseudo-)fcc crystal structure are formed. This crystal structure is preserved after the annealing procedure which qualifies these coatings for use in applications where temperatures of up to 600 {sup 0}C are reached.

  18. Ordering phenomena in FeCo-films and Fe/Cr-multilayers: an X-ray and neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, B.

    2001-07-01

    The following topics are covered: critical phenomena in thin films, critical adsorption, finite size scaling, FeCo Ising model, kinematical scattering theory for thin films, FeCo thin films, growth and characterisation of single crystal FeCo thin films, X-ray study of ordering in FeCo films, antiferromagnetic coupling in Fe/Cr multilayers, neutron scattering on Fe/Cr multilayers (WL)

  19. Switching of magnetic easy-axis using crystal orientation for large perpendicular coercivity in CoFe2O4 thin film

    Science.gov (United States)

    Shirsath, Sagar E.; Liu, Xiaoxi; Yasukawa, Yukiko; Li, Sean; Morisako, Akimitsu

    2016-07-01

    Perpendicular magnetization and precise control over the magnetic easy axis in magnetic thin film is necessary for a variety of applications, particularly in magnetic recording media. A strong (111) orientation is successfully achieved in the CoFe2O4 (CFO) thin film at relatively low substrate temperature of 100 °C, whereas the (311)-preferred randomly oriented CFO is prepared at room temperature by the DC magnetron sputtering technique. The oxygen-deficient porous CFO film after post-annealing gives rise to compressive strain perpendicular to the film surface, which induces large perpendicular coercivity. We observe the coercivity of 11.3 kOe in the 40-nm CFO thin film, which is the highest perpendicular coercivity ever achieved on an amorphous SiO2/Si substrate. The present approach can guide the systematic tuning of the magnetic easy axis and coercivity in the desired direction with respect to crystal orientation in the nanoscale regime. Importantly, this can be achieved on virtually any type of substrate.

  20. Single Crystals (M = Fe, Co)

    Science.gov (United States)

    Cabrera-Baez, M.; Magnavita, E. Thizay; Ribeiro, Raquel A.; Avila, Marcos A.

    2014-06-01

    FeGa3 and related compounds have been subjects of recent investigation for their interesting thermoelectric, electronic, and magnetic behaviors. Here, single crystals of FeGa3- y Ge y were grown by the self-flux technique with effective y = 0, 0.09(1), 0.11(1), and 0.17(1) in order to investigate the evolution of the diamagnetic semiconducting compound FeGa3 into a ferromagnetic metal, which occurs through the electron doping and band structure modifications that result from substitution of Ge for Ga. Heat capacity and magnetization measurements reveal non-Fermi liquid behavior in the vicinity of the transition from a paramagnetic to ferromagnetic ground state, suggesting the presence of a ferromagnetic quantum critical point (FMQCP). We also present the first results of hole doping in this system by the growth of FeGa3- y Zn y single crystals, and electron- and hole doping of the related compound CoGa3 by CoGa3- y Ge y and CoGa3- y Zn y crystal growths, aiming to search for further routes to band structure and charge carrier tuning, thermoelectric optimization, and quantum criticality in this family of compounds. The ability to tune the charge carrier type warrants further investigation of the MGa3 system's thermoelectric properties above room temperature.

  1. Pulsed laser deposition of permanent magnetic Nd2Fe14B thin films

    NARCIS (Netherlands)

    Geurtsen, A.J.M.; Kools, J.C.S.; Wit, L.; Lodder, J.C.

    1996-01-01

    Pulsed Laser Deposition (PLD) is applied to deposit thin (thickness typically 100 nm) films of Nd2Fe14B. It is shown that films can be grown which have the desired composition and phase. Nd2Fe14B grows with the c-axis along the film normal on 110 Al2O3 single crystal substrates covered with a Ta lay

  2. Evidence of non-Dzyaloshinskii–Moriya ferromagnetism in epitaxial BiFeO3 films

    NARCIS (Netherlands)

    Prokhorov, V.G.; Kaminsky, G.G.; Kim, J.M.; Eom, T.W.; Park, J.S.; Lee, Y.P.; Svetchnikov, V.L.; Levtchenko, G.G.; Nikolaenko, Y.M.; Khokhlov, V.A.

    2011-01-01

    X-ray diffraction analysis and high-resolution electron microscopy of BiFeO3 films prepared by dc magnetron sputtering on single-crystal LaAlO3 (001) substrates reveal that the films have a highly c-oriented orthorhombic crystalline structure. The magnetic properties of the BiFeO3 films are typical

  3. Preparation of high magneto-optical performance and crystalline quality Ce{sub 1}Gd{sub 2}Fe{sub 5−x}Ga{sub x}O{sub 12} films on CLNGG substrate crystal

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Qiu-ping; Zheng, Ze-yuan; Lin, Nan-xi; Liu, Xiao-feng; Hong, Can-huang; Hu, Xiao-lin, E-mail: linamethyst@fzu.edu.cn; Zhuang, Nai-feng; Chen, Jian-zhong, E-mail: j.z.chen@fzu.edu.cn

    2016-11-01

    Thin films of Ce{sub 1}Gd{sub 2}Fe{sub 5−x}Ga{sub x}O{sub 12} (Ce,Ga:GIG) were prepared on Gd{sub 3}Ga{sub 5}O{sub 12} (GGG) and Ca{sub 2.90}Li{sub 0.30}Nb{sub 1.93}Ga{sub 2.76}O{sub 12} (CLNGG) substrates by using radio frequency magnetron sputtering technique. The phase, grain orientation, surface morphology, transmittance, magnetism and magnetic circular dichroism (MCD) properties of films were analyzed. And the effects of lattice mismatch and non-magnetic Ga{sup 3+}-doping were discussed. The results show that the films with higher crystallized quality and lower stress can be obtained by growing on CLNGG than on GGG. Moreover, the coercive force, magnetization, magneto-optical effect intensity and orientation of film can be effectively regulated by adjusting Ga{sup 3+}-doped concentration. - Highlights: • With excellent magneto-optical performance, Ce,Ga:GIG film has a good application prospect. • Ce,Ga:GIG film with high quality were prepared on CLNGG by RF magnetron sputtering. • Crystalline quality and morphology of films are intently related to the substrate. • Ga{sup 3+} doping obviously affect on magnetism and magneto-optical property of Ce:GIG film.

  4. Magnetic Properties and Microstructure of FeOx/Fe/FePt and FeOx/FePt Films

    Directory of Open Access Journals (Sweden)

    Jai-Lin Tsai

    2013-01-01

    Full Text Available The Fe(6 nm/FePt film with perpendicular magnetization was deposited on the glass substrate. To study the oxygen diffusion effect on the coupling of Fe/FePt bilayer, the plasma oxidation with 0.5~7% oxygen flow ratio was performed during sputtered part of Fe layer and formed the FeOx(3 nm/Fe(3 nm/FePt trilayer. Two-step magnetic hysteresis loops were found in trilayer with oxygen flow ratio above 1%. The magnetization in FeOx and Fe/FePt layers was decoupled. The moments in FeOx layer were first reversed and followed by coupled Fe/FePt bilayer. The trilayer was annealed again at 500°C and 800°C for 3 minutes. When the FeOx(3 nm/Fe(3 nm/FePt trilayer was annealed at 500°C, the layers structure was changed to FeOx(6 nm/FePt bilayer due to oxygen diffusion. The hard-magnetic FeOx(6 nm/FePt film was coupled with single switching field. The FeOx/(disordered FePt layer structure was observed with further annealing at 800°C and presented soft-magnetic loop. In summary, the coupling between soft-magnetic Fe, FeOx layer, and hard-magnetic L10 FePt layer can be controlled by the oxygen diffusion behavior, and the oxidation of Fe layer was tuned by the annealing temperature. The ordered L10 FePt layer was deteriorated by oxygen and became disordered FePt when the annealed temperature was up to 800°C.

  5. Annealing effects of chemically synthesized FePt nanocrystal films

    Science.gov (United States)

    Hyun, Changbae; Lee, Doh C.

    2005-03-01

    Chemically synthesized FePt nanocrystals can exhibit room temperature ferromagnetism after being annealed at temperatures above ˜500^oC[1]. The thermal annealing changes the crystal structure from face-centered cubic to the hard magnetic face-centered tetragonal phase. In thick nanocrystal films, the coercivity can be quite large, however, the coercivity of thin films has been found to decrease significantly with decreasing thickness, even losing the room temperature ferromagnetism in some cases[2]. In order to help determine how the microscopic magnetic structure in these thin films evolves with film thickness, we studied using magnetic force microscopy (MFM), under external applied fields, films consisting of 4 to 15 nanocrystal monolayers. We cast smooth films of 4 nm diameter FePt nanocrystals and annealed them at temperatures ranging from 400 to 650^oC, acquiring MFM images as a function of annealing temperature. Thin FePt films showed lower coercivity than thick films. To help interpret the MFM images, complementary magnetic and structural data was obtained using SQUID magnetometry, x-ray diffraction, and transmission electron microscopy (TEM). [1] S. Sun et al., Science 287, 1989 (2000). [2] G. A. Held et al., Journal of Applied Physics 95, 1481 (2004)

  6. Interface-assisted magnetoresistance behavior for ultrathin NiFe films

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Shao-Long; Chen, Xi; Yang, Kang [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Han, Gang [Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083 (China); Teng, Jiao; Li, Xu-Jing; Yang, Guang; Liu, Qian-Qian; Liu, Yi-Wei [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Ding, Lei [School of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China); Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-11-01

    Interface-assisted magnetoresistance (MR) behavior has been studied in Ta/MgO/NiFe/MgO/Ta multilayers by inserting a Mg metal layer between the NiFe layer and the top MgO layer. It is shown that MR ratio is about 31% larger than that in the films without Mg insertion. X-ray photoelectron spectroscopy and high resolution transmission electron microscope analyses show that the enhanced MR is primarily ascribed to effective control of chemical states at the NiFe/MgO interface and crystallization of the top MgO layer. - Highlights: • We studied magnetic and electric transport properties of ultrathin NiFe films. • Interface chemical states have strong influence on MR in NiFe films. • Crystallization of the top MgO layer has influence on MR in NiFe films.

  7. Enhanced saturation magnetization in buckypaper-films of thin walled carbon nanostructures filled with Fe3C, FeCo, FeNi, CoNi, Co and Ni crystals: the key role of Cl.

    Science.gov (United States)

    Guo, Jian; Lan, Mu; Wang, Shanling; He, Yi; Zhang, Sijie; Xiang, Gang; Boi, Filippo S

    2015-07-21

    We report an advanced chemical vapour deposition approach which allows the direct in situ synthesis of cm-length ultrathin buckypapers comprising carbon nanostructures filled with Fe3C, FeCo, FeNi, CoNi, Co and Ni by sublimation and pyrolysis of single or combined metallocenes with very low quantities of dichlorobenzene. As a result, extremely high saturation magnetizations of 117 emu g(-1), 90 emu g(-1) and 80 emu g(-1) are obtained for the specific cases of Fe3C, FeCo and FeNi, respectively, while variable saturation magnetizations of 70 emu g(-1), 58 emu g(-1) and 6.7 emu g(-1) are obtained for Co, CoNi and Ni respectively.

  8. Evolution of structure and magnetic properties of nanocrystalline FeXN thin films via Ta and Al addition

    Institute of Scientific and Technical Information of China (English)

    Wu Guo-Guang; Wu Dong-Ping; Zheng Kuo-Hai; Wei Fu-Lin; Yang Zheng; A. S. Kamzin

    2005-01-01

    Nanocrystalline FeAlN and FeTaN films are prepared by direct growth and crystallization of their as-deposited amorphous films, respectively. The two films both show soft magnetism of nanocrystalline, but their uniaxial anisotropy is observed to be different from each other. Measurements of microstructure reveal that Ta addition leads to higher N-solubility in these films, and results in larger lattice dilation and more compressive stress. The uniaxial anisotropy is the consequence of the anisotropic distribution of interstitial N atoms in an α-Fe lattice. Al is easy to react with nitrogen, therefore the α-Fe is purer in the FeAlN film than in the FeTaN film and the stress is tensile in the FeAlN film. The difference in anisotropy may be attributed to the different microstructures in both films.

  9. Structural and Magnetic Properties of Ultrathin Fe Films on Pt(001) Surface

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-Juan; HE Ke; JIA Jin-Feng; XUE Qi-Kun

    2005-01-01

    @@ Magnetic anisotropy evolution of ultrathin Fe films grown on Pt(001) single-crystal surface is investigated by UHVin situ surface magneto-optical Kerr effect (SMOKE) measurement. After annealing at ~ 600 K, the magnetic anisotropy of Fe film switches from in-plane to perpendicular at low coverage, leading to a spin reorientationtransition (SRT). Meanwhile, in the range of 3-4 monolayer (ML) thickness, the coercivity of the Fe polar hysteresis loop decreases dramatically. Further scanning tunnelling microscopy (STM) and low energy electron diffraction (LEED) investigation correlates the magnetic properties with the film structures. We attribute this SRT to the formation of Fe-Pt ordered alloy.

  10. Single crystal Fe elements patterned by one-step selective chemical wet etching

    NARCIS (Netherlands)

    Sun, Li; Wong, P.K.J.; Niu, Daxin; Zou, Xiao; Zhai, Ya; Wu, Jing; Xu, Yongbing; Zhai, Hongru

    2010-01-01

    A technique has been developed to pattern single crystal ultrathin Fe films by selective chemical wet etching of the Au capping layer and then simultaneous oxidization of the ferromagnetic Fe layer underneath. The focused magneto-optical Kerr effect and ferromagnetic resonance measurements demonstra

  11. Fe-doped TiO 2 thin films

    Science.gov (United States)

    Mardare, Diana; Nica, Valentin; Teodorescu, Cristian-Mihail; Macovei, Dan

    2007-09-01

    The reactive sputtering technique was used to obtain undoped and Fe-doped TiO 2 thin films deposited on glass substrates. At 250 °C substrate temperature, undoped TiO 2 films crystallize in a mixed rutile/anatase phase, while Fe-doped films exhibit the rutile phase only. Presence of Fe 3+ ions into the TiO 2 lattice is suggested by the intensity variation of forbidden 1s → 3d transitions between the Ti and Fe K-edges. Ti K-edge EXAFS data are assessed to a mixture of the two kinds of surroundings, a rutile-like crystalline phase, identified also by X-ray diffraction, and a nanosized or amorphous anatase-like surrounding. The local atomic order about Fe atoms is quite different and could be related also to an amorphous phase. The Swanepoel method is used to obtain the dispersion of the refractive index below the interband absorption edge. The dispersion energy, the single-oscillator energy and the coordination number of the Ti atoms are evaluated using the single-oscillator model (Wemple-DiDomenico).

  12. 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.

  13. On dewetting of thin films due to crystallization (crystallization dewetting).

    Science.gov (United States)

    Habibi, Mehran; Rahimzadeh, Amin; Eslamian, Morteza

    2016-03-01

    Drying and crystallization of a thin liquid film of an ionic or a similar solution can cause dewetting in the resulting thin solid film. This paper aims at investigating this type of dewetting, herein termed "crystallization dewetting", using PbI2 dissolved in organic solvents as the model solution. PbI2 solid films are usually used in X-ray detection and lead halide perovskite solar cells. In this work, PbI2 films are fabricated using spin coating and the effect of major parameters influencing the crystallization dewetting, including the type of the solvent, solution concentration, drying temperature, spin speed, as well as imposed vibration on the substrate are studied on dewetting, surface profile and coverage, using confocal scanning laser microscopy. Simplified hydrodynamic governing equations of crystallization in thin films are presented and using a mathematical representation of the process, it is phenomenologically demonstrated that crystallization dewetting occurs due to the absorption and consumption of the solution surrounding a growing crystal. Among the results, it is found that a low spin speed (high thickness), a high solution concentration and a low drying temperature promote crystal growth, and therefore crystallization dewetting. It is also shown that imposed vibration on the substrate can affect the crystal size and crystallization dewetting.

  14. Tuning Superconductivity in FeSe Thin Films via Magnesium Doping.

    Science.gov (United States)

    Qiu, Wenbin; Ma, Zongqing; Liu, Yongchang; Shahriar Al Hossain, Mohammed; Wang, Xiaolin; Cai, Chuanbing; Dou, Shi Xue

    2016-03-01

    In contrast to its bulk crystal, the FeSe thin film or layer exhibits better superconductivity performance, which recently attracted much interest in its fundamental research as well as in potential applications around the world. In the present work, tuning superconductivity in FeSe thin films was achieved by magnesium-doping technique. Tc is significantly enhanced from 10.7 K in pure FeSe films to 13.4 K in optimized Mg-doped ones, which is approximately 1.5 times higher than that of bulk crystals. This is the first time achieving the enhancement of superconducting transition temperature in FeSe thin films with practical thickness (120 nm) via a simple Mg-doping process. Moreover, these Mg-doped FeSe films are quite stable in atmosphere with Hc2 up to 32.7 T and Tc(zero) up to 12 K, respectively, implying their outstanding potential for practical applications in high magnetic fields. It was found that Mg enters the matrix of FeSe lattice, and does not react with FeSe forming any other secondary phase. Actually, Mg first occupies Fe-vacancies, and then substitutes for some Fe in the FeSe crystal lattices when Fe-vacancies are fully filled. Simultaneously, external Mg-doping introduces sufficient electron doping and induces the variation of electron carrier concentration according to Hall coefficient measurements. This is responsible for the evolution of superconducting performance in FeSe thin films. Our results provide a new strategy to improve the superconductivity of 11 type Fe-based superconductors and will help us to understand the intrinsic mechanism of this unconventional superconducting system.

  15. Thermal Expansion Coefficients of Thin Crystal Films

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.

  16. Magnetic Properties of Co-Fe-B Amorphous Films Thermomagnetically Treated with Different Field Directions

    Directory of Open Access Journals (Sweden)

    Zhe Liu

    2012-01-01

    Full Text Available Co-Fe-B films were prepared by electroless plating. As-deposited films were thermomagnetically treated in the applied magnetic field of 500 Oe with different field directions at 300°C for 1 hour. The effects of magnetic field direction of thermomagnetic treatment on the structure and magnetic properties of Co-Fe-B thin films were investigated. It is found that two phases existed in annealed Co-Fe-B films: one is weak crystallized CoFe phase, the other being amorphous phase. The surface morphologies of the treated films are found to be affected by the direction of thermomagnetic treatment field. The results also show that the magnetic properties of thermomagnetically treated films are influenced greatly by the treatment field direction.

  17. Ferroelectric size effects in multiferroic BiFeO3 thin films

    NARCIS (Netherlands)

    Chu, Y.-H.; Zhao, T.; Cruz, M.P.; Zhan, Q.; Yang, P.L.; Martin, L.W.; Huijben, M.; Yang, C.H.; Zavaliche, F.; Zheng, H.; Ramesh, R.

    2007-01-01

    Ferroelectric size effects in multiferroic BiFeO3 have been studied using a host of complementary measurements. The structure of such epitaxial films has been investigated using atomic force microscopy, transmission electron microscopy, and x-ray diffraction. The crystal structure of the films has b

  18. Crystallization of zirconia based thin films.

    Science.gov (United States)

    Stender, D; Frison, R; Conder, K; Rupp, J L M; Scherrer, B; Martynczuk, J M; Gauckler, L J; Schneider, C W; Lippert, T; Wokaun, A

    2015-07-28

    The crystallization kinetics of amorphous 3 and 8 mol% yttria stabilized zirconia (3YSZ and 8YSZ) thin films grown by pulsed laser deposition (PLD), spray pyrolysis and dc-magnetron sputtering are explored. The deposited films were heat treated up to 1000 °C ex situ and in situ in an X-ray diffractometer. A minimum temperature of 275 °C was determined at which as-deposited amorphous PLD grown 3YSZ films fully crystallize within five hours. Above 325 °C these films transform nearly instantaneously with a high degree of micro-strain when crystallized below 500 °C. In these films the t'' phase crystallizes which transforms at T > 600 °C to the t' phase upon relaxation of the micro-strain. Furthermore, the crystallization of 8YSZ thin films grown by PLD, spray pyrolysis and dc-sputtering are characterized by in situ XRD measurements. At a constant heating rate of 2.4 K min(-1) crystallization is accomplished after reaching 800 °C, while PLD grown thin films were completely crystallized already at ca. 300 °C.

  19. 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.

  20. 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.

  1. Thermodynamic and Kinetic Study of Crystallization Reaction of Fe/Dy Multilayers Form Amorphous State

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To give further insight into the behavior of Fe/Dy multilayers in the crystallization from as-deposited amorphous state, free energy diagram of Fe/Dy system was constructed based on Miedema semiempirical theory. It is shown that the crystallization of amorphous films is controlled by both thermodynamic and kinetic conditions. The calculated free energies of crystalline Fe and Dy are significantly lower than those in the amorphous states, which provide thermodynamic driving force for crystallization. During annealing, the kinetic phase evolution of the multilayers is controlled by free energy barrier of nucleation and critical-size of new phase nucleus. Thus it explains the experimental results that Fe crystallites formed first followed by Dy grains, whereas crystalline Fe-Dy intermetallic compounds were not observed during annealing at moderate temperatures.

  2. Magnetic properties and magnetization reversal of α-Fe nanowires deposited in alumina film

    Science.gov (United States)

    Peng, Yong; Zhang, Hao-Li; Pan, Shan-Lin; Li, Hu-Lin

    2000-05-01

    Uniform arrays of Fe nanowires were prepared by electrochemical deposition of iron into nanoporous anodic aluminum oxide films. The microstructure and crystal structures of the nanowires were studied by transmission electron microscopy and electron diffraction. It was found that each nanowire looked like a chain of dots and each dot in the chain was supposed to be a single crystal of α-Fe. Each dot was shown to be a single magnetic domain. The magnetic properties of a uniform array of Fe nanowires and the magnetization reversal in a Fe nanowire were investigated by Mössbauer spectroscopy and vibrating sample magnetometry, which demonstrated that the film of Fe nanowires in alumina had superior perpendicular magnetic characteristics. The magnetic studies also revealed that the moments of each single domain dot were oriented along the chain. Experimental results could be interpreted by the reversal model of "chains of spheres" with the symmetric fanning mechanism.

  3. STUDY ON CO-ELECTRODEPOSITION OF Bi-Fe ALLOY FILMS IN ORGANIC BATH

    Institute of Scientific and Technical Information of China (English)

    G.R. Li; Y.X. Tong; G.K. Liu

    2003-01-01

    The cyclic voltametry and potentiostatic electrolysis was used to investigate the preparation of Bi-Fe alloy films in LiClO4-DMSO (dimethylsulfoxide) system. The effects of several factors including the potential of deposition, current density and concentration of iron and bismuth in the solution on the Fe content in the alloy deposits were studied. Experimental results indicated that the amorphous alloy films of Bi-Fe containing Fe 4.40wt%-33. 67wt% could be prepared by controlling the system composition and deposition conditions. They were gray, uniform, metallic luster and adhered firmly to the copper substrates analyzed by EDS, SEM and XRD. After heat treatment of crystallization at 270℃ for 1h, the crystal phase of Bi-Fe can be found in XRD patterns.

  4. Removal of FePO{sub 4} and Fe{sub 3}(PO{sub 4}){sub 2} crystals on the surface of passive fillers in Fe{sup 0}/GAC reactor using the acclimated bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Bo, E-mail: laibo1981@163.com [Department of Environmental Science and Engineering, School of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Research Center of Water Pollution Control Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Zhou, Yuexi [Research Center of Water Pollution Control Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Yang, Ping [Department of Environmental Science and Engineering, School of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Wang, Juling [Research Center of Water Pollution Control Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Yang, Jinghui [China National Petroleum Corporation Research Institute of Safety and Environment Technology HSE Assessment Center, Beijing 100012 (China); Li, Huiqiang [Department of Environmental Science and Engineering, School of Architecture and Environment, Sichuan University, Chengdu 610065 (China)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Fe{sub 3}(PO{sub 4}){sub 2} and FePO{sub 4} crystals would weaken treatment efficiency of Fe{sup 0}/GAC reactor. Black-Right-Pointing-Pointer Fe{sub 3}(PO{sub 4}){sub 2} and FePO{sub 4} crystals could be removed by the acclimated bacteria. Black-Right-Pointing-Pointer FeS and sulfur in the passive film would be removed by the sulfur-oxidizing bacteria. Black-Right-Pointing-Pointer Develop a cost-effective bio-regeneration technology for the passive fillers. - Abstract: As past studies presented, there is obvious defect that the fillers in the Fe{sup 0}/GAC reactor begin to be passive after about 60 d continuous running, although the complicated, toxic and refractory ABS resin wastewater can be pretreated efficiently by the Fe{sup 0}/GAC reactor. During the process, the Fe{sub 3}(PO{sub 4}){sub 2} and FePO{sub 4} crystals with high density in the passive film are formed by the reaction between PO{sub 4}{sup 3-} and Fe{sup 2+}/Fe{sup 3+}. Meanwhile, they obstruct the formation of macroscopic galvanic cells between Fe{sup 0} and GAC, which will lower the wastewater treatment efficiency of Fe{sup 0}/GAC reactor. In this study, in order to remove the Fe{sub 3}(PO{sub 4}){sub 2} and FePO{sub 4} crystals on the surface of the passive fillers, the bacteria were acclimated in the passive Fe{sup 0}/GAC reactor. According to the results, it can be concluded that the Fe{sub 3}(PO{sub 4}){sub 2} and FePO{sub 4} crystals with high density in the passive film could be decomposed or removed by the joint action between the typical propionic acid type fermentation bacteria and sulfate reducing bacteria (SRB), whereas the PO{sub 4}{sup 3-} ions from the decomposition of the Fe{sub 3}(PO{sub 4}){sub 2} and FePO{sub 4} crystals were released into aqueous solution which would be discharged from the passive Fe{sup 0}/GAC reactor. Furthermore, the remained FeS and sulfur (S) in the passive film also can be decomposed or removed easily by the

  5. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  6. Fe-doped epitaxial YBCO films prepared by chemical solution deposition

    Institute of Scientific and Technical Information of China (English)

    Hong Zhang; Yong Zhao; Wentao Wang; Min Pan; Ming Lei

    2014-01-01

    YBa2Cu3O7-d (YBCO)-coated conductors have wide-ranging potential in large-scale applications such as superconducting maglev trains and superconducting elec-tric cables, but low current carrying capability restrains the practical application of YBCO-coated conductors at high temperatures and high magnetic fields. It is crucial to develop YBCO-coated conductors with high critical cur-rent density. In this paper, epitaxial, dense, smooth, and crack-free Fe-doped YBCO films were prepared on a LaAlO3 single crystal substrate via a fluorine-free polymer-assisted metal organic deposition method. The effects of the dilute Fe doping on microstructure and superconduc-ting character of YBCO films were investigated. The crit-ical temperature for superconducting of the Fe-doped YBCO films decreases slightly. However, the in-field critical current density of YBCO films improves with dilute Fe doping of amounts less than x=0.005, compared to the pure YBCO film. Therefore, the current carrying capability of YBCO film can improve by doping with appropriate amounts of Fe. This means that dilute Fe doping in YBCO films may be a feasible way to prepare high-performance coated conductors.

  7. 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.

  8. Domains in Ferroic Crystals and Thin Films

    CERN Document Server

    Tagantsev, Alexander K; Fousek, Jan

    2010-01-01

    Domains in Ferroic Crystals and Thin Films presents experimental findings and theoretical understanding of ferroic (non-magnetic) domains developed during the past 60 years. It addresses the situation by looking specifically at bulk crystals and thin films, with a particular focus on recently-developed microelectronic applications and methods for observation of domains with techniques such as scanning force microscopy, polarized light microscopy, scanning optical microscopy, electron microscopy, and surface decorating techniques. Domains in Ferroic Crystals and Thin Films covers a large area of material properties and effects connected with static and dynamic properties of domains, which are extremely relevant to materials referred to as ferroics. In most solid state physics books, one large group of ferroics is customarily covered: those in which magnetic properties play a dominant role. Numerous books are specifically devoted to magnetic ferroics and cover a wide spectrum of magnetic domain phenomena. In co...

  9. Morphology and crystal structure control of alpha-Fe2O3 films by hydrothermal-electrochemical deposition in the presence of Ce3+ and/or acetate, F- ions

    OpenAIRE

    Yılmaz, Özgür; Ünal, Uğur

    2016-01-01

    Hydrothermal-electrochemical growth of Hematite (alpha-Fe2O3) thin films in the presence of Ce3+ and/or CH3COO- and F- ions is reported. Primary attention is paid to understanding the synergistic effect of temperature and additive ions on the growth of Hematite particles. The literature describes the shape-controlled electrodeposition of iron oxide films, but these reports involve low-temperature depositions (

  10. Topological Defects in Liquid Crystal Films

    Institute of Scientific and Technical Information of China (English)

    DUAN Yi-Shi; ZHAO Li; ZHANG Xin-Hui; SI Tie-Yan

    2007-01-01

    A topological theory of liquid crystal films in the presence of defects is developed based on the φ-mapping topological current theory. By generalizing the free-energy density in "one-constant" approximation, a covariant freeenergy density is obtained, from which the U(1) gauge field and the unified topological current for monopoles and strings in liquid crystals are derived. The inner topological structure of these topological defects is characterized by the winding numbers of φ-mapping.

  11. On the crystallization of amorphous germanium films

    Science.gov (United States)

    Edelman, F.; Komem, Y.; Bendayan, M.; Beserman, R.

    1993-06-01

    The incubation time for crystallization of amorphous Ge (a-Ge) films, deposited by e-gun, was studied as a function of temperature between 150 and 500°C by means of both in situ transmission electron microscopy and Raman scattering spectroscopy. The temperature dependence of t0 follows an Arrhenius curve with an activation energy of 2.0 eV for free-sustained a-Ge films. In the case where the a-Ge films were on Si 3N 4 substrate, the activation energy of the incubation process was 1.3 eV.

  12. Pillar shape modulation in epitaxial BiFeO3–CoFe2O4 vertical nanocomposite films

    Directory of Open Access Journals (Sweden)

    Dong Hun Kim

    2014-08-01

    Full Text Available Self-assembled epitaxial CoFe2O4-BiFeO3 nanocomposite films, in which pillars of CoFe2O4 grow within a single crystal BiFeO3 matrix, show both ferrimagnetism and ferroelectricity. The pillars typically have a uniform cross-section, but here two methods are demonstrated to produce a width modulation during growth by pulsed laser deposition. This was achieved by growing a blocking layer of BiFeO3 to produce layers of separated pillars or pillars with constrictions, or by changing the temperature during growth to produce bowling-pin shaped pillars. Modulated nanocomposites showed changes in their magnetic anisotropy compared to nanocomposites with uniform width. The magnetic anisotropy was interpreted as a result of magnetoelastic and shape anisotropies.

  13. Texture induced magnetic anisotropy in Fe3O4 films

    Science.gov (United States)

    Liu, Er; Huang, Zhaocong; Zheng, Jian-Guo; Yue, Jinjin; Chen, Leyi; Wu, Xiumei; Sui, Yunxia; Zhai, Ya; Tang, Shaolong; Du, Jun; Zhai, Hongru

    2015-10-01

    This letter reports a free energy density model for textured films in which the related physical concept and expression of magneto-texture anisotropy energy are presented. The structural characterization and out-of-plane angular dependence ferromagnetic resonance of strongly textured Fe3O4 films were systematically investigated. We found that the typical free energy density model for polycrystalline film cannot be applied to the textured films. With the introduction of magneto-texture anisotropy energy in the free energy density model for thin films, we simulated and quantitatively determined the competing anisotropies in (111)-textured Fe3O4 films.

  14. Effect of epitaxial strain and lattice mismatch on magnetic and transport behaviors in metamagnetic FeRh thin films

    Directory of Open Access Journals (Sweden)

    Yali Xie

    2017-05-01

    Full Text Available We grew 80 nm FeRh films on different single crystals with various lattice constants. FeRh films on SrTiO3 (STO and MgO substrates exhibit an epitaxial growth of 45° in-plane structure rotation. In contrast, FeRh on LaAlO3 (LAO displays a mixed epitaxial growth of both 45° in-plane structure rotation and cube-on-cube relationships. Due to the different epitaxial growth strains and lattice mismatch values, the critical temperature for the magnetic phase transition of FeRh can be changed between 405 and 360 K. In addition, the external magnetic field can shift this critical temperature to low temperature in different rates for FeRh films grown on different substrates. The magnetoresistance appears a maximum value at different temperatures between 320 and 380 K for FeRh films grown on different substrates.

  15. Effect of epitaxial strain and lattice mismatch on magnetic and transport behaviors in metamagnetic FeRh thin films

    Science.gov (United States)

    Xie, Yali; Zhan, Qingfeng; Shang, Tian; Yang, Huali; Wang, Baomin; Tang, Jin; Li, Run-Wei

    2017-05-01

    We grew 80 nm FeRh films on different single crystals with various lattice constants. FeRh films on SrTiO3 (STO) and MgO substrates exhibit an epitaxial growth of 45° in-plane structure rotation. In contrast, FeRh on LaAlO3 (LAO) displays a mixed epitaxial growth of both 45° in-plane structure rotation and cube-on-cube relationships. Due to the different epitaxial growth strains and lattice mismatch values, the critical temperature for the magnetic phase transition of FeRh can be changed between 405 and 360 K. In addition, the external magnetic field can shift this critical temperature to low temperature in different rates for FeRh films grown on different substrates. The magnetoresistance appears a maximum value at different temperatures between 320 and 380 K for FeRh films grown on different substrates.

  16. Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

    Science.gov (United States)

    Rao, Pratibha; Godbole, R. V.; Bhagwat, Sunita

    2016-10-01

    In this work, Pd:NiFe2O4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe2O4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost.

  17. Inkjet printing of single-crystal films

    Science.gov (United States)

    Minemawari, Hiromi; Yamada, Toshikazu; Matsui, Hiroyuki; Tsutsumi, Jun'ya; Haas, Simon; Chiba, Ryosuke; Kumai, Reiji; Hasegawa, Tatsuo

    2011-07-01

    The use of single crystals has been fundamental to the development of semiconductor microelectronics and solid-state science. Whether based on inorganic or organic materials, the devices that show the highest performance rely on single-crystal interfaces, with their nearly perfect translational symmetry and exceptionally high chemical purity. Attention has recently been focused on developing simple ways of producing electronic devices by means of printing technologies. `Printed electronics' is being explored for the manufacture of large-area and flexible electronic devices by the patterned application of functional inks containing soluble or dispersed semiconducting materials. However, because of the strong self-organizing tendency of the deposited materials, the production of semiconducting thin films of high crystallinity (indispensable for realizing high carrier mobility) may be incompatible with conventional printing processes. Here we develop a method that combines the technique of antisolvent crystallization with inkjet printing to produce organic semiconducting thin films of high crystallinity. Specifically, we show that mixing fine droplets of an antisolvent and a solution of an active semiconducting component within a confined area on an amorphous substrate can trigger the controlled formation of exceptionally uniform single-crystal or polycrystalline thin films that grow at the liquid-air interfaces. Using this approach, we have printed single crystals of the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) (ref. 15), yielding thin-film transistors with average carrier mobilities as high as 16.4cm2V-1s-1. This printing technique constitutes a major step towards the use of high-performance single-crystal semiconductor devices for large-area and flexible electronics applications.

  18. Effect of film thickness on the magneto-structural properties of ion beam sputtered transition metal-metalloid FeCoNbB/Si (100) alloy thin films

    Science.gov (United States)

    Gupta, Pooja; Tripathi, Yagyanidhi; Kumar, Dileep; Rai, S. K.; Gupta, Mukul; Reddy, V. R.; Svec, Peter

    2016-08-01

    The structure and magnetic properties of ion beam sputtered transition metal-metalloid FeCoNbB/Si(100) alloy thin film have been studied as a function of film thickness using complementary techniques of x-ray reflectivity (XRR), grazing incidence x-ray diffraction, and magneto optical Kerr effect. Thicknesses of the films range from ˜200 to 1500 Å. The coercivity of all the films ranges between 4 and 14 Oe, which suggests soft magnetic nature of FeCoNbB/Si thin films. Films with thickness up to 800 Å are amorphous in nature and are found to possess uniaxial magnetic anisotropy in the film plane, although no magnetic field was applied during deposition. The presence of the two fold symmetry in such amorphous thin films may be attributed to quenched-in stresses developed during deposition. Upon increasing the film thickness to ˜1200 Å and above, the structure of FeCoNbB films transforms from amorphous to partially nanocrystalline structure and has bcc-FeCo nanocrystalline phase dispersed in remaining amorphous matrix. The crystalline volume fraction (cvf) of the films is found to be proportional to the film thickness. Azimuthal angle dependence of remanence confirms the presence of in-plane four-fold anisotropy (FFA) in the crystalline film with cvf ˜75%. Synchrotron x-ray diffraction measurement using area detector suggests random orientation of crystallites and thus clearly establishes that FFA is not related to texture/cubic symmetry in such polycrystalline thin films. As supported by asymmetric Bragg diffraction measurements, the origin of FFA in such partially crystalline thin film is ascribed to the additional compressive stresses developed in the film upon crystallization. Results indicate that promising soft magnetic properties in such films can be optimized by controlling the film thickness. The revelation of controllable and tunable anisotropy suggests that FeCoNbB thin films can have potential application in electromagnetic applications.

  19. 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.

  20. Preparation and Properties of Amorphous NiFe/Cu/NiFe Thin Films

    Institute of Scientific and Technical Information of China (English)

    YE Yun; JIANG Ya-dong; HU Wen-cheng; ZENG Hong-juan

    2004-01-01

    The amorphous of Permalloy on the copper subtract was studied using composite electroplating method. A portion of hydrogen brings the counteraction on the surface of cathode leading nickel-iron alloys to be anomalous in the process of co-depositing. The results of X-ray diffraction (XRD) show that the Ni-Fe alloys layer is amorphous. The Giant Magneto -Impedance (GMI) effect of Ni-Fe alloys was obtained under the optimal conditions, dependence on the soft magnetic property of Ni-Fe amorphous thin film. As a result, the ratios△ Z/Z of NiFe/Cu/NiFe amorphous thin film are 30% at 40 kHz which is in low frequency. Furthermore, the GMI value of NiFe/Cu/NiFe amorphous thin film with a sandwich structure is higher than that of single-layer ferromagnetic films of the same thickness.

  1. Variable substrate temperature deposition of CoFeB film on Ta for manipulating the perpendicular coercive forces

    Science.gov (United States)

    Lakshmanan, Saravanan; Rao, Subha Krishna; Muthuvel, Manivel Raja; Chandrasekaran, Gopalakrishnan; Therese, Helen Annal

    2017-08-01

    Magnetization of Ta/CoFeB/Ta trilayer films with thick layer of CoFeB deposited under different substrate temperatures (Ts) via ultra-high vacuum DC sputtering technique has been measured with the applied magnetic field parallel and perpendicular to the plane of the film respectively to study the perpendicular coercive forces of the film. The samples were further analyzed for its structural, topological, morphological, and electrical transport properties. The core chemical states for the elements present in the CoFeB thin film were analyzed by XPS studies. Magnetization studies reveal the existence of perpendicular coercive forces in CoFeB films deposited only at certain temperatures such as RT, 450 °C, 475 °C and 500 °C. CoFeB film deposited at 475 °C exhibited a maximum coercivity of 315 Oe and a very low saturation magnetization (Ms) of 169 emu/cc in perpendicular direction. This pronounced effect in perpendicular coercive forces observed for CoFeB475 could be attributed to the effect of temperature in enhancing the crystallization of the film at the Ta/CoFeB interfaces. However at temperatures higher than 475 °C the destruction of the Ta/CoFeB interface due to intermixing of Ta and CoFeB results in the disappearance of magnetic anisotropy.

  2. Characteristics of a thick film ethanol gas sensor made of mechanically treated LaFeO3 powder

    Science.gov (United States)

    Suhendi, Endi; Witra, Hasanah, Lilik; Syarif, Dani Gustaman

    2017-05-01

    In this work, fabrication of LaFeO3 thick film ceramics for ethanol gas sensor made of mechanically treated (milling) powder was studied. The thick films were fabricated using screen printing technique from LaFeO3 powder treated by HEM (High Energy Milling). The films were baked at 800°C for one hour and analyzed using XRD and SEM. Sensitivity of the films was studied by measuring resistance of them at various temperatures in a chamber containing air with and without ethanol gas. Data of XRD showed that the thick film crystalizes in orthorombic structure with space group of Pn*a. SEM data showed that the films consisted of small grains with grain size of about 225 nm. According to the electrical data, the LaFeO3 thick films that produced in this work could be applied as ethanol gas with operating temperature of about 275°C.

  3. High-temperature superconductivity in potassium-coated multilayer FeSe thin films.

    Science.gov (United States)

    Miyata, Y; Nakayama, K; Sugawara, K; Sato, T; Takahashi, T

    2015-08-01

    The recent discovery of possible high-temperature (T(c)) superconductivity over 65 K in a monolayer FeSe film on SrTiO3 (refs 1-6) triggered a fierce debate on how superconductivity evolves from bulk to film, because bulk FeSe crystal exhibits a T(c) of no higher than 10 K (ref. 7). However, the difficulty in controlling the carrier density and the number of FeSe layers has hindered elucidation of this problem. Here, we demonstrate that deposition of potassium onto FeSe films markedly expands the accessible doping range towards the heavily electron-doped region. Intriguingly, we have succeeded in converting non-superconducting films with various thicknesses into superconductors with T(c) as high as 48 K. We also found a marked increase in the magnitude of the superconducting gap on decreasing the FeSe film thickness, indicating that the interface plays a crucial role in realizing the high-temperature superconductivity. The results presented provide a new strategy to enhance and optimize T(c) in ultrathin films of iron-based superconductors.

  4. Structure and magnetic properties of SmCo5/X (X=Fe, Fe-Co, Co) magnetic bilayer films on MgO(110) substrate

    Science.gov (United States)

    Suzuki, Ataru; Hotta, Yusuke; Yamada, Makoto; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi; Inaba, Nobuyuki

    2017-10-01

    Sm17Co83 (at%) films are prepared on bcc-Cr(211), bcc-Fe(211), bcc-Fe65Co35(211), and hcp-Co(1 1 (_) 00) underlayers hetero-epitaxially grown on MgO(110) substrates at 500 °C by using a UHV-MBE system. The growth behavior and the structures are investigated by in-situ reflection high-energy electron diffraction and X-ray diffraction. Sm-Co(1 1 (_) 00) single-crystal films of RT5 ordered structure with the c-axis lying in the film plane grow epitaxially on the underlayers. Small volumes of amorphous phases are interpreted to be involved in the films deposited on these underlayers. The crystal lattice of RT5 magnetic film is slightly deformed from the bulk hexagonal structure, which is caused possibly by the lattice mismatch with the underlayer. The order degree of film deposited on Cr underlayer is higher (S=0.77) than those prepared on Fe, Fe65Co35, and Co underlayers (S: 0.67-0.71). The films show in-plane uniaxial magnetic anisotropies reflecting the magnetocrystalline anisotropy of SmCo5 crystal.

  5. 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.

  6. Spin Seebeck effect in insulating epitaxial γ-Fe2O3 thin films

    Science.gov (United States)

    Jiménez-Cavero, P.; Lucas, I.; Anadón, A.; Ramos, R.; Niizeki, T.; Aguirre, M. H.; Algarabel, P. A.; Uchida, K.; Ibarra, M. R.; Saitoh, E.; Morellón, L.

    2017-02-01

    We report the fabrication of high crystal quality epitaxial thin films of maghemite (γ-Fe2O3), a classic ferrimagnetic insulating iron oxide. Spin Seebeck effect (SSE) measurements in γ-Fe2O3/Pt bilayers as a function of sample preparation conditions and temperature yield a SSE coefficient of 0.5(1) μV/K at room temperature. Dependence on temperature allows us to estimate the magnon diffusion length in maghemite to be in the range of tens of nanometers, in good agreement with that of conducting iron oxide magnetite (Fe3O4), establishing the relevance of spin currents of magnonic origin in magnetic iron oxides.

  7. Crystal structure of fiber structured pentacene thin films

    OpenAIRE

    2007-01-01

    This PhD thesis presents a technique based on the grazing incidence crystal truncation rod (GI-CTR) X-ray diffraction method used to solve the crystal structure of substrate induced fiber structured organic thin films. The crystal structures of pentacene thin films grown on technologically relevant gate dielectric substrates are reported. It is widely recognized, that the intrinsic charge transport properties in organic thin film transistors (OTFTs) depend strongly on the crystal structur...

  8. Reactively sputtered Fe3O4-based films for spintronics

    Institute of Scientific and Technical Information of China (English)

    Li Peng; Jin Chao; Mi Wen-Bo; Bai Hai-Li

    2013-01-01

    Half metallic polycrystalline,epitaxial Fe3O4 films and Fe3O4-based heterostructures for spintronics were fabricated by DC reactive magnetron sputtering.Large tunneling magnetoresistance was found in the polycrystalline Fe3O4 films and attributed to the insulating grain boundaries.The pinning effect of the moments at the grain boundaries leads to a significant exchange bias.Frozen interfacial/surface moments induce weak saturation of the high-field magnetoresistance.The films show a moment rotation related butterfly-shaped magnetoresistance.It was found that in the films,natural growth defects,antiphase boundaries,and magnetocrystaltine anisotropy play important roles in high-order anisotropic magnetoresistance.Spin injection from Fe3O4 films to semiconductive Si and ZnO was measured to be 45% and 28.5%,respectively.The positive magnetoresistance in the Fe3O4-based heterostructures is considered to be caused by a shift of the Fe3O4 eg ↑ band near the interface.Enhanced magnetization was observed in Fe3O4/BiFeO3 heterostructures experimentally and further proved by first principle calculations.The enhanced magnetization can be explained by spin moments of the thin BiFeO3 layer substantially reversing into a ferromagnetic arrangement under a strong coupling that is principally induced by electronic orbital reconstruction at the interface.

  9. MBE growth of Fe-based superconducting films

    Science.gov (United States)

    Ueda, S.; Yamagishi, T.; Takeda, S.; Agatsuma, S.; Takano, S.; Mitsuda, A.; Naito, M.

    2011-11-01

    We report MBE growth of the iron-based superconductors, Sr1-xKxFe2As2, Ba1-xKxFe2As2, and SmFeAs(O,F). In the growth of Sr1-xKxFe2As2 and Ba1-xKxFe2As2 films, the key to incorporating volatile K in films is low-temperature (300-350 °C) growth in reduced As flux. The highest Tc so far obtained are Tcon (Tcend) = 33.4K (31.0 K) and 38.3 K (35.5 K) for Sr1-xKxFe2As2 and Ba1-xKxFe2As2, respectively. In the growth of superconducting SmFeAs(O,F), we have adopted two approaches. In the first approach, we first grew F-free SmFeAsO films, and subsequently introduced F to the films via F diffusion from an overlayer of SmF3 or NdF3. In the second approach, we attempted the growth of as-grown superconducting SmFeAs(O,F) films by coevaporating Sm, SmF3, Fe, and As. In both the approaches, the growth temperature was as high as 650 °C. So far better results have been obtained by the first F diffusion method. The films prepared by F diffusion showed Tcon (Tcend) = 52 K (48.6 K) whereas the as-grown films showed Tcon = 47 K but with a long transition tail.

  10. Enhanced photovoltaic currents in strained Fe-doped LiNbO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Ryotaro [Division of Physics, Institute of Liberal Education, School of Medicine, Nihon University, 31-10, Ooyaguchi-kamicho, Itabashi-ku, Tokyo 173-8601 (Japan); Takahashi, Shusuke; Kitanaka, Yuuki; Oguchi, Takeshi; Noguchi, Yuji; Miyayama, Masaru [Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan)

    2015-12-15

    We investigate the impact of strain on photovoltaic current (J{sub z}) characteristics for iron-doped LiNbO{sub 3} (Fe-LN) under visible light illumination by thin-film experiments. The J{sub z} values are demonstrated to be dramatically enhanced for the film with a tensile strain along the P{sub s} direction, which is over 500 times as large as that of the bulk (strain-free) Fe-LN crystals. Density functional theory (DFT) calculations show that the tensile strain increases an off-center displacement of Fe{sup 2+} that is opposite to the P{sub s} direction. Our experimental and DFT study demonstrates that the control of the lattice strain is effective in enhancing the photovoltaic effect in the Fe-LN system. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Optical and magnetic properties of PAA@Fe nanocomposite films

    Directory of Open Access Journals (Sweden)

    Jing-jing Zhang

    2013-07-01

    Full Text Available A simple method to fabricate porous anodic alumina films embedded with Fe is reported. The films exhibit vivid structural colors and magnetic properties after being synthesized by an ac electrodeposition method. The optical properties of the samples can be effectively tuned by varying the oxidation time of aluminum. The coercivity mechanism of the Fe nanowires in our case is consistent with fanning reversal mode. PAA@Fe films can be used in many areas including decoration, display and multifunctional anti-counterfeiting applications.

  12. Crystal structure of the Fe-member of usovite

    Directory of Open Access Journals (Sweden)

    Matthias Weil

    2015-06-01

    Full Text Available Crystals of the title compound, with the idealized composition Ba2CaFeAl2F14, dibarium calcium iron(II dialuminium tetradecafluoride, were obtained serendipitously by reacting a mixture of the binary fluorides BaF2, CaF2 and AlF3 in a leaky steel reactor. The compound crystallizes in the usovite structure type (Ba2CaMgAl2F14, with Fe2+ cations replacing the Mg2+ cations. The principal building units are distorted [CaF8] square-antiprisms (point group symmetry 2, [FeF6] octahedra (point group symmetry -1 and [AlF6] octahedra that are condensed into undulating 2∞[CaFeAl2F14]4− layers parallel (100. The Ba2+ cations separate the layers and exhibit a coordination number of 12. Two crystal structure models with a different treatment of the disordered Fe site [mixed Fe/Ca occupation, model (I, versus underoccupation of Fe, model (II], are discussed, leading to different refined formulae Ba2Ca1.310 (15Fe0.690 (15Al2F14 [model (I] and Ba2CaFe0.90 (1Al2F14 [model (II].

  13. 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.

  14. Electroplated Fe-Co-Ni films prepared from deep-eutectic-solvent-based plating baths

    Directory of Open Access Journals (Sweden)

    Takeshi Yanai

    2016-05-01

    Full Text Available We fabricated soft magnetic films from DES-based plating baths, and investigated magnetic properties of the plated films. The plating baths were obtained by stirring the mixture of choline chloride, ethylene glycol, FeCl2 ⋅ 4H2O, NiCl2 ⋅ 6H2O and CoCl2 ⋅ 6H2O. The composition of the electroplated film depended on the amount of the reagent in the plating bath, and we consequently obtained the films with various composition. The current efficiency of the plating process shows high values (> 88 % in the wide composition range. The soft magnetic films with low coercivity were obtained at the Fe compositions of ≈ 30 at.% and > 80 at.%, and we found that low coercivity could be realized by the control of the film composition. We also found that the Fe-rich films prepared from DES-based plating bath have some advantages as a soft magnetic phase for a nanocomposite magnet due to their high saturation magnetization and very fine crystal structure.

  15. 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.

  16. Thickness dependent activity of nanostructured TiO 2/α-Fe 2O 3 photocatalyst thin films

    Science.gov (United States)

    Akhavan, O.

    2010-12-01

    The effect of thickness of TiO 2 coating on synergistic photocatalytic activity of TiO 2 (anatase)/α-Fe 2O 3/glass thin films as photocatalysts for degradation of Escherichia coli bacteria in a low-concentration H 2O 2 solution and under visible light irradiation was investigated. Nanograined α-Fe 2O 3 films with optical band-gap of 2.06 eV were fabricated by post-annealing of thermal evaporated iron oxide thin films at 400 °C in air. Increase in thickness of the Fe 2O 3 thin film (here, up to 200 nm) resulted in a slight reduction of the optical band-gap energy and an increase in the photoinactivation of the bacteria. Sol-gel TiO 2 coatings were deposited on the α-Fe 2O 3 (200 nm)/glass films, and then, they were annealed at 400 °C in air for crystallization of the TiO 2 and formation of TiO 2/Fe 2O 3 heterojunction. For the TiO 2 coatings with thicknesses ≤50 nm, the antibacterial activity of the TiO 2/α-Fe 2O 3 (200 nm) was found to be better than the activity of the bare α-Fe 2O 3 film. The optimum thickness of the TiO 2 coating was found to be 10 nm, resulting in about 70 and 250% improvement in visible light photo-induced antibacterial activity of the TiO 2/α-Fe 2O 3 thin film as compared to the corresponding activity of the bare α-Fe 2O 3 and TiO 2 thin films, respectively. The improvement in the photoinactivation of bacteria on surface of TiO 2/α-Fe 2O 3 was assigned to formation of Ti-O-Fe bond at the interface.

  17. Effect of Metallic Film in Diamond Growth from an Fe-Ni-C System at High Temperature and High Pressure

    Institute of Scientific and Technical Information of China (English)

    许斌; 李木森; 尹龙卫; 崔建军; 宫建红

    2003-01-01

    The metallic film surrounding a diamond single crystal, which plays an important role in the diamond growth from an Fe-Ni-C system, has been successfully investigated by using transmission-electron microscopy (TEM),Raman spectroscopy and x-ray photo-electron spectroscopy (XPS). Diamond and graphite were not found in surface layer (near diamond) of the film by TEM and Raman spectroscopy, but a parallel relationship exists between the (111) plane of γ-(Fe,Ni) and the (100) plane of (Fe, Ni)3C in this region. Compared with that of solvent metal (catalyst) near diamond, the binding energy in the valence bands of iron, nickel and carbon atoms of the film has an increase of 0.9 eV. According to the microstructures on the film obtained by the TEM, Raman spectra, and XPS, the catalytic mechanism of the film may be assumed as follows. In the surface layer of the film,iron and nickel atoms in the γ-(Fe, Ni) lattice can absorb carbon atoms in the (Fe, Ni)3C lattice and make them transform to an sp3-like state. Then carbon atoms with the sp3-like structure are separated from the (Fe,Ni)3C and stack on the growing diamond crystal. This study provides a direct evidence for the diamond growth from a metallic catalyst-graphite system under high temperature and high pressure.

  18. Anomalous Hall effect studies on Tb-Fe thin films

    Science.gov (United States)

    Rajasekhar, P.; Deepak Kumar, K.; Markandeyulu, G.

    2016-08-01

    Tbx Fe100-x (with x=11, 25, 31 and 44) thin films were prepared with the substrates kept at a temperature of 300 °C and the Hall resistivities and electrical resistivities were investigated in the temperature range 25-300 K. The sign of Hall resistivity is found to change from positive for x=31 to negative for x=44 film at temperatures 25 K and 300 K, reflecting the compensation of Tb and Fe magnetic moments between these two compositions. Perpendicular magnetic anisotropy was observed in the films of x=25 and 31 at 25 K as well as at 300 K. The Hall resistivity is seen to increase for the films of x=11 and 31 with increasing temperature, while it decreases for the films of x=25 and 44 with increasing temperature. The temperature coefficients of electrical resistivities of these films are seen to be positive. The presence of perpendicular magnetic anisotropy (refers to magnetic anisotropy, in this paper) in the temperature range 25-300 K in Tb25Fe75 and Tb31Fe69 and their metallic nature are indicators that the Tb-Fe films deposited at higher temperatures are more suitable for magneto optic data storage applications than their amorphous counterparts, due to the stability of the former.

  19. The influence of the film thickness of nanostructured alpha-Fe2O3 on water photooxidation.

    Science.gov (United States)

    Souza, Flavio Leandro; Lopes, Kirian Pimenta; Longo, Elson; Leite, Edson Roberto

    2009-02-28

    The present work shows the influence of the film thickness in the optical and photoelectrochemical properties of nanostructured alpha-Fe(2)O(3) thin film. We found that the film thickness has a strong influence on the optical absorption and the results here reported can help in the design of nanostructured alpha-Fe(2)O(3) with superior performance for water photo-oxidation. The results show that the optical property of the hematite film is affected by the film thickness, probably due to the stress induced by the strong interaction between film and substrate. This stress generates defects in the crystal lattice of the hematite film, increasing the (e(-))-(h(+)) recombination process.

  20. Structural, electron transportation and magnetic behavior transition of metastable FeAlO granular films.

    Science.gov (United States)

    Bai, Guohua; Wu, Chen; Jin, Jiaying; Yan, Mi

    2016-04-14

    Metal-insulator granular film is technologically important for microwave applications. It has been challenging to obtain simultaneous high electrical resistivity and large saturation magnetization due to the balance of insulating non-magnetic and metallic magnetic components. FeAlO granular films satisfying both requirements have been prepared by pulsed laser deposition. The as-deposited film exhibits a high resistivity of 3700 μΩ∙cm with a negative temperature coefficient despite that Fe content (0.77) exceeds the percolation threshold. This originates from its unique microstructure containing amorphous Fe nanoparticles embedded in Al2O3 network. By optimizing the annealing conditions, superior electromagnetic properties with enhanced saturation magnetization (>1.05 T), high resistivity (>1200 μΩ∙cm) and broadened Δf (>3.0 GHz) are obtained. Phase separation with Al2O3 aggregating as inclusions in crystallized Fe(Al) matrix is observed after annealing at 673 K, resulting in a metallic-like resistivity. We provide a feasible way to achieve both high resistivity and large saturation magnetization for the FeAlO films with dominating metallic component and show that the microstructure can be tuned for desirable performance.

  1. Co{sub 100−x}Fe{sub x} magnetic thick films prepared by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre, M. del C., E-mail: carmenaguirre@famaf.unc.edu.ar [Instituto de Física Enrique Gaviola-Conicet-Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba (Argentina); Farías, E. [Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba (Argentina); Abraham, J.; Urreta, S.E. [Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba (Argentina)

    2015-04-05

    Highlights: • Low iron containing films are compact, with rounded, relatively uniform surfaces. • Larger Fe contents exhibit nanowall networks covering the surface. • Coercivity in the out of plane configuration is larger than in the easy axis direction. • Co-rich films nucleate and grow by a 3DP diffusion controlled mechanism. • For equiatomic Fe{sub 50}Co{sub 50} films, nucleation tends to become instantaneous. - Abstract: Co–Fe films are grown onto plane pre-treated Cu foils; the effects of the alloy composition on the morphology and the crystal texture of the electrodeposited films and their anisotropic magnetic hysteresis properties are explored. Nucleation and crystallization mechanisms in these Co-rich layers are also investigated with pulse-reverse plating techniques, using the first cathodic pulse current–time transients. In the diffusion controlled regime the deposition mechanism is found to involve progressive nucleation with three-dimensional (3D) growth, except for the equiatomic Fe{sub 50}Co{sub 50} solution where nucleation tends to become instantaneous. The different morphologies and size scales observed are described and correlated with coercivity. The films are electrodeposited onto electrochemically pre-treated Cu substrates from feeds of nominal Fe/Co mol ratios between 0/100 and 50/50. The composition of the deposited layers, as determined by energy dispersive X-ray spectroscopy, are quite close to the nominal values. Cyclic voltammetry determinations exhibit only a single reduction process on the cathode, indicating that a unique (Co{sub 100−x}Fe{sub x}) phase grows. Depending on composition and on the substrate pre-treatment, these layers exhibit textures with features of different sizes. X ray diffraction patterns indicate that the nanostructures with Fe contents above 20 at.% crystallize in a body-centered cubic cell, while samples with Fe contents below this value are fcc. Regarding the effect of composition on the

  2. Perovskite solar cells: Shedding light on film crystallization

    Science.gov (United States)

    Bakr, Osman M.; Mohammed, Omar F.

    2017-06-01

    A study on the formation of methylammonium lead iodide perovskite films reveals that light illumination influences the crystallization kinetics, therefore affecting the final photovoltaic performance of these materials.

  3. Strength anomaly in B2 FeAl single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimi, K.; Hanada, S.; Yoo, M.H. [Oak Ridge National Lab., TN (United States); Matsumoto, N. [Tohoku Univ. (Japan). Graduate School

    1994-12-31

    Strength and deformation microstructure of B2 Fe-39 and 48%Al single crystals (composition given in atomic percent), which were fully annealed to remove frozen-in vacancies, have been investigated at temperatures between room temperature and 1073K. The hardness of as-homogenized Fe-48Al is higher than that of as-homogenized Fe-39Al while after additional annealing at 698K the hardness of Fe-48Al becomes lower than that of Fe-39Al. Fe-39Al single crystals slowly cooled after homogenizing at a high temperature were deformed in compression as a function of temperature and crystal orientation. A peak of yield strength appears around 0.5T{sub m} (T{sub m} = melting temperature). The orientation dependence of the critical resolved shear stress does not obey Schmid`s law even at room temperature and is quite different from that of b.c.c. metals and B2 intermetallics at low temperatures. At the peak temperature slip transition from <111>-type to <001>-type is found to occur macroscopically and microscopically, while it is observed in TEM that some of the [111] dislocations decompose into [101] and [010] on the (1096I) plane below the peak temperature. The physical sources for the positive temperature dependence of yield stress of B2 FeAl are discussed based on the obtained results.

  4. Visible light catalysis of rhodamine B using nanostructured Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films.

    Science.gov (United States)

    Mahadik, M A; Shinde, S S; Mohite, V S; Kumbhar, S S; Moholkar, A V; Rajpure, K Y; Ganesan, V; Nayak, J; Barman, S R; Bhosale, C H

    2014-04-05

    The Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) composite films are deposited using spray pyrolysis method onto glass and FTO coated substrates. The structural, morphological, optical and photocatalytic properties of Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films are studied. XRD analysis confirms that films are polycrystalline with rhombohedral and tetragonal crystal structures for Fe2O3 and TiO(2) respectively. The photocatalytic activity was tested for the degradation of Rhrodamine B (Rh B) in aqueous medium. The rate constant (-k) was evaluated as a function of the initial concentration of species. Substantial reduction in concentrations of organic species was observed from COD and TOC analysis. Photocatalytic degradation effect is relatively higher in case of the TiO(2)/Fe(2)O(3) than TiO(2) and Fe(2)O(3) thin film photoelectrodes in the degradation of Rh B and 98% removal efficiency of Rh B is obtained after 20min. The photocatalytic experimental results indicate that TiO(2)/α-Fe(2)O(3) photoelectrode is promising material for removing of water pollutants.

  5. Deposition and Magnetic Properties of Fe3O4/Fe/Fe3O4Tri-layer Films

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Fe3O4/Fe/Fe3O4 (MIM) tri-layer films (200 nm/12~93 nm/200 nm) were prepared on Si(100) by DC-magnetron reactive-sputtering followed by air- or vacuum-annealing at 280~400℃ for 1.5 h, respectively. Magnetic properties and phases under different sandwich and annealing conditions were studied. In MIM structure, the incorporation of the interlayer iron does increase the magnetization measured under 8 kOe (M8K), but reduce coercivity (Hc). The Hc of as deposited films decreases from 354 Oe to 74 Oe; while M8K increases from 254 to 392 emu/cc. By annealing in air, the whole MIM tri-layer film becomes γ-Fe2Oa, Hc is about 550 Oe and M8K is around 250 emu/cc. The coercivity mechanism of as-deposited and annealed MIM tri layer films belongs to domain-wall pinning type. δM plots show that when the interlayer Fe thickness is 12 nm, the Fe and Fe3O4 layers are decoupled in the as-deposited and annealed states; while it is coupled in the as deposited state when the Fe thickness increases to 23 nm. Vacuum annealing of the MIM films leads to increase in both coercivity and magnetization, and to enhance the exchange coupling between layers.

  6. Structural and optical properties of low temperature synthesized Nanostructured BiFeO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, H.B. [Department of Physics, Manipur University, Imphal 795003, Manipur (India); Bobby Singh, S., E-mail: sbsoram@gmail.co [Department of Physics, Manipur University, Imphal 795003, Manipur (India); Boinis Singh, Ng [Department of Physics, Manipur University, Imphal 795003, Manipur (India)

    2011-02-01

    Nanostructured bismuth ferrite (BiFeO{sub 3}) thin films were deposited on glass substrate by the sol-gel process. The as-fired film at 250 {sup o}C was found to be amorphous crystallizing to pure rhombohedral phase after annealing at 450 {sup o}C for 2 h in air. The XRD pattern shows that the sample is polycrystalline in nature. The average grain size of the film calculated from the XRD data was found to be 16 nm. The as-fired film show high transmittance that decreases after crystallization. The absorption edge of the films was found to be sharper and shifting towards the lower energy as the annealing temperature increases. The optical energy band gaps of the amorphous and crystalline films were found to be 2.63 and 2.31 eV, respectively. The refractive indices of the amorphous and crystalline films were 2.05 and 2.26, respectively.

  7. Electrophysical and Magnetoresistive Properties of Thin Film Alloy Ni80Fe20

    Directory of Open Access Journals (Sweden)

    О.V. Pylypenko

    2016-10-01

    Full Text Available In this work, the complex investigations of crystal structure and phase state, thermoresistive (resistivity, temperature coefficient of resistance, strain (integral and differential coefficients of longitudinal tensosensitivity at the strain interval Δεl = 0-1 % and magnetoresistive (magnetoresistance and anisotropic magnetoresistance properties of the thin film alloy Ni80Fe20 in the thicknesses range 10-45 nm. The effects of condensation conditions and heat treatments on referred above properties have been analyzed.

  8. Moment Mapping of bcc Fe1-xMnx Alloy Films on MgO(001)

    Science.gov (United States)

    Idzerda, Yves; Bhatkar, Harsh; Arenholz, Elke

    2015-03-01

    The magnetic moments of ~ 20 nm single crystal films of compositionally graded Fe1-xMnx films (0.1 Pauling curve and disappearance of the moment at x =0.15. By generating a compositional variation around this critical concentration and subsequently using spatially resolved mapping of the X-ray absorption at the Fe and Mn L3-edge using linear and circular polarized soft X-rays, the local composition and elemental moments can be simultaneously mapped across the surface of the sample. The Fe moment is found to gradually reduce with increasing Mn content with a very abrupt decline at x =0.15. Surprisingly, the Mn moment shows a very small net moment (<0.1 muB) at all compositions, suggesting a complicated Mn spin structure.

  9. Studies on electrochemically grown Cd-Fe-Se thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mahalingam, T. [Alagappa Univ., Karaikudi (India). Dept. of Physics; Ajou Univ., Suwon (Korea, Republic of). Dept. of Electrical and Computer Engineering; Thanikaikarasan, S.; Raja, M.; Sanjeeviraja, C. [Alagappa Univ., Karaikudi (India). Dept. of Physics; Lee, S.; Moon, H.; Kim, Y.D. [Ajou Univ., Suwon (Korea, Republic of). Dept. of Molecular Science and Technology; Sebastian, P.J. [CIE-UNAM, Temixco, Morelos (Mexico); Chipas Polytechnical Univ., Chipas (Mexico)

    2007-01-15

    This paper presented the results of a study that investigated the electrochemical, structural, compositional, morphological and photoelectrochemical properties of cadmium ferrous selenide (Cd-Fe-Se) semiconducting thin films electrodeposited onto conducted tin oxide (SnO{sub 2}) coated glass substrates at various cadmium sulfate concentrations in the deposition bath. Experimental details were provided along with results of typical cyclic voltammograms of Cd-Fe-Se thin film cathodically deposited from an acid solution containing CdSO{sub 4}, FeSO{sub 4} and SeO{sub 2} without any additives. Variations in film thickness were determined along with compositional analysis and morphological studies. Photoelectrochemical (PEC) solar cell studies were performed in a cell consisting of photoelectrode (Cd-Fe{sub S}e), a platinum counter electrode and a saturated dalomel reference electrode. A hot probe method identified the nature of the thin film to be n-type, while the structure was found to be hexagon for CdSe, tetragonal for {alpha}-FeSe and orthorhombic for FeSe{sub 2}. According to energy dispersive analysis of X-rays (EDAX), the stoichiometric values of Cd and Se are obtained at higher concentration of CdSO{sub 4}. The maximum concentration of CD{sup 2+} ions in the solution bath yielded thin films with smooth surfaces. 18 refs., 1 tab., 6 figs.

  10. Composition and size dependence of magnetic properties of FePt/Fe exchange-spring films

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yu; Zhang, Zhe; Duan, Nian; Wang, Jiawei; Chen, Yuang; Tong, Bei; Yang, Xiaofei; Zhang, Yue, E-mail: yue-zhang@mail.hust.edu.cn

    2014-12-15

    The composition and size dependence of the magnetic properties of FePt/Fe exchange-spring bilayer films was studied using micromagnetic simulation. Based on the simulated hysteresis loops for composite layers with an identical thickness of 20 nm and different composition ratios, it can be observed that when the thickness ratio of Fe is 10%, an exchange-spring effect with a negative nucleation field appears; the switching field is greatly reduced compared to the rigid magnetic FePt, and the squareness ratio reaches its maximum value. When the thickness ratio of Fe is 25% and more, the nucleation fields become positive; meanwhile, the coercivity is smaller than the switching field, and the squareness ratio decreases because of the increase in the thickness of the Fe film. In addition, at a fixed thickness ratio and total volume, the switching field of the FePt/Fe bilayer films is further reduced, accompanied by a decrease in the squareness ratio due to an increase in the thickness of the Fe layer. - Highlights: • Exchange-spring behavior of FePt/Fe multi-layers was studied via micro-magnetic simulation. • As total thickness is 20 nm, optimal magnetic property is shown when the thickness ratio of Fe is 10%. • As total thickness is 20 nm, nucleation fields are positive when the thickness ratio of Fe is 25% and larger. • As total thickness is 20 nm, coercivity is greatly reduced when the thickness ratio of Fe is 25% and larger. • Under fixed volume and the thickness ratio of Fe (10%), switching field can be reduced by reducing the bottom size.

  11. Numerical study of the effective magnetocrystalline anisotropy and magnetostriction in polycrystalline FeGa films

    Science.gov (United States)

    Dean, Julian; Bryan, M. T.; Morley, N. A.; Hrkac, G.; Javed, A.; Gibbs, M. R. J.; Allwood, D. A.

    2011-08-01

    The high interest in FeGa films is due to the high magnetostriction present in single crystal thin films. There is, however, significant reduction in the magnetostriction when grown using sputtering. The reduction is explained here using finite element analysis by considering the local magnetocrystalline and magnetoelastic behavior of the grains within the sample. It is shown that, if the saturation magnetostrictive constant for each grain in a polycrystalline structure is of the order of 400 ppm, this is reduced to less than 90 ppm when the crystallites are randomly orientated. Furthermore, the inherent stress due to the sample fabrication leads to an increase in the anisotropy field. This work suggests that, with low stress fabrication and aligning the in-plane orientation of the crystallites, the potential in unlocking FeGa as a thin film for sensory applications can be realised.

  12. Extraordinary Hall effect on Fe-rich amorphous thin films and Fe-rich/Cu multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Michea, S. [Universidad de Santiago de Chile, Avda. Ecuador, 3493, Estacion Central, Santiago (Chile); Denardin, J.C., E-mail: juliano.denardin@usach.cl [Universidad de Santiago de Chile, Avda. Ecuador, 3493, Estacion Central, Santiago (Chile); Gamino, M.; Dorneles, L.S. [Departamento de Fisica, Universidade Federal de Santa Maria, Santa Maria 97105-900, RS (Brazil); Correa, M.A. [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitario Lagoa Seca, 59072-970 - Natal, RN - Brazil (Brazil)

    2012-08-15

    In this study we investigated the magnetic and transport properties of thin Fe-rich amorphous films and Fe-rich/Cu multilayers. We compared the extraordinary Hall effect in these two types of samples and discussed it in terms of thickness and sample structure. The thicker films exhibited a strong in-plane magnetic anisotropy, and by decreasing film thickness both saturated Hall resistivity and Hall sensitivity increase. A Hall resistivity value of 20 {mu} Ohm-Sign cm is observed in 100 nm thick Fe-rich films at 12 K and a sensitivity of 1.3 Ohm-Sign /T is obtained at room temperature. Electrical conductance increases and Hall resistivity decreases when the films are sandwiched with Cu.

  13. Comparison of Microstructural and Morphological Properties of Electrodeposited Fe-Cu Thin Films with Low and High Fe : Cu Ratio

    Directory of Open Access Journals (Sweden)

    Umut Sarac

    2013-01-01

    Full Text Available Fe-Cu films with low and high Fe : Cu ratio have been produced from the electrolytes with different Fe ion concentrations at a constant deposition potential of −1400 mV versus saturated calomel electrode (SCE by electrodeposition technique onto indium tin oxide (ITO coated conducting glass substrates. It was observed that the variation of Fe ion concentration in the electrolyte had a very strong influence on the compositional, surface morphological, and microstructural properties of the Fe-Cu films. An increase in the Fe ion concentration within the plating bath increased the Fe content, consequently Fe : Cu ratio within the films. The crystallographic structure analysis showed that the Fe-Cu films had a mixture of face-centered cubic (fcc Cu and body centered cubic (bcc α-Fe phases. The average crystallite size decreased with the Fe ion concentration. The film electrodeposited from the electrolyte with low Fe ion concentration exhibited a morphology consisting of dendritic structures. However, the film morphology changed from dendritic structure to cauliflower-like structure at high Fe ion concentration. The surface roughness and grain size were found to decrease significantly with increasing Fe ion concentration in the electrolyte. The significant differences observed in the microstructural and morphological properties caused by the change of Fe ion concentration in the electrolyte were ascribed to the change of Fe : Cu ratio within the films.

  14. MBE growth of Fe-based superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, S. [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)] [TRIP, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075 (Japan)] [New Energy and Industrial Technology Development Organization (NEDO), Kawasaki, Kanagawa 212-8554 (Japan); Yamagishi, T.; Takeda, S. [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)] [TRIP, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075 (Japan); Agatsuma, S.; Takano, S. [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Mitsuda, A. [Department of Physics, Kyushu Univeristy, Hakozaki, Fukuoka 812-8588 (Japan); Naito, M., E-mail: minaito@cc.tuat.ac.jp [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)] [TRIP, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075 (Japan)

    2011-11-15

    Successful MBE growth of (AE,K)-122 (AE = Sr and Ba) with T{sub c} = 38 K and Ln-1111 (Ln = Sm) films with T{sub c} = 52 K. (Sr,K)-122 and (Ba,K)-122 films including volatile K were grown at temperatures as low as 300{approx}350 deg. C in reduced As flux. SmFeAs(O,F) films were prepared by two approaches. In the first approach, F was diffused to F-free SmFeAsO films from a thin SmF{sub 3} (or NdF{sub 3}) overlayer. In the second approach, as-grown superconducting SmFeAsO films were grown by coevaporation of Sm, SmF{sub 3}, Fe, and As in oxygen atmosphere. We report MBE growth of the iron-based superconductors, Sr{sub 1-x}K{sub x}Fe{sub 2}As{sub 2}, Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2}, and SmFeAs(O,F). In the growth of Sr{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} and Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} films, the key to incorporating volatile K in films is low-temperature (300-350 deg. C) growth in reduced As flux. The highest T{sub c} so far obtained are T{sub c}{sup on}(T{sub c}{sup end})=33.4K (31.0 K) and 38.3 K (35.5 K) for Sr{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} and Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2}, respectively. In the growth of superconducting SmFeAs(O,F), we have adopted two approaches. In the first approach, we first grew F-free SmFeAsO films, and subsequently introduced F to the films via F diffusion from an overlayer of SmF{sub 3} or NdF{sub 3}. In the second approach, we attempted the growth of as-grown superconducting SmFeAs(O,F) films by coevaporating Sm, SmF{sub 3}, Fe, and As. In both the approaches, the growth temperature was as high as 650 deg. C. So far better results have been obtained by the first F diffusion method. The films prepared by F diffusion showed T{sub c}{sup on} (T{sub c}{sup end}) = 52 K (48.6 K) whereas the as-grown films showed T{sub c}{sup on} = 47 K but with a long transition tail.

  15. 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.

  16. 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.

  17. Magnetostriction of Fe81Ga19 oriented crystals

    Institute of Scientific and Technical Information of China (English)

    Wang Zhi-Bin; Liu Jing-Hua; Jiang Cheng-Bao

    2010-01-01

    The effect of the orientation on the magnetostrietion in Fe81Ga19 alloy has been investigated experimentally and theoretically. The Fe81Ga19[001]and[110]oriented crystals were prepared and the magnetostriction was measured under different pre-stress. The saturation magnetostriction of the[001]oriented crystal increases from 170x10-6 to 330x 10-6 under the pre-stress from O to 50 Mpa. The[110]oriented crystal has a saturation magnetostriction from 20x10-6 to 140x10-6 with the compressive pre-stress from O to 40 Mpa. The magnetostriction of[001]and[110]oriented crystals has been simulated based on the phenomenological theory. The domain rotation path has been determined and the resultant magnetostrietion calculated under different pre-stress. The experimental and simulated results both show that the[001]oriented crystal exhibits better magnetostriction than[110]oriented crystal. The enhancement of the saturation magnetostriction by the compressive pre-stress in the[110]oriented crystal is higher than that in the[001]oriented crystal.

  18. AFM research on Fe-based nanocrystal crystallization mechanism

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The cross-section pattern of Fe-based alloy ribbon (Fe73.5Cu1Nb3Si13.5B9) annealed at different temperatures was investigated by AFM (atomic force microscope), and the effect mechanism of Nb and Cu in Fe-based alloy ribbon annealing was analyzed with XRD diffraction crystal analysis technique and other research results. New concepts of encapsulated grain, Nb vacancy cluster, Nb-B atom cluster and so on were proposed and used to describe the formation mechanism of α-Fe (Si) nanocrystal. Finally, a three-phase (separation phase, encapsulated phase and nanocrystalline phase) interconnected structure model in Fe-based nanocrystalline alloy was established.

  19. Kinetics of sucrose crystallization in whey protein films.

    Science.gov (United States)

    Dangaran, Kirsten L; Krochta, John M

    2006-09-20

    The kinetics of sucrose crystallization in whey protein isolate (WPI) films was studied at 25 degrees C in four different relative humidity environments: 23, 33, 44, and 53%. The effects of protein matrix, crystallization inhibitors, and storage environment on the rate constants of sucrose crystallization were determined using the Avrami model of crystallization. It was found that a cross-linked, denatured whey protein (WP) matrix more effectively hindered sucrose crystallization than a protein matrix of native WP. The crystallization inhibitors tested were lactose, raffinose, modified starch (Purity 69), and polyvinylpyrrolidone (Plasdone C15). Raffinose and modified starch were determined to be the more effective inhibitors of sucrose crystallization. At lower relative humidities (23, 33, and 44%), the cross-linked protein matrix played a more important role in sucrose crystallization than the inhibitors. As relative humidity increased (53%), the crystallization inhibitors were more central to controlling sucrose crystallization in WPI films.

  20. Growth and thermoelectric properties of FeSb2 films produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Canulescu, Stela; SUN, Ye; Schou, Jørgen

    FeSb2, a strongly correlated semiconductor, has promising application potential for thermoelectric cooling at cryogenic temperatures [1,2]. Single crystals of FeSb2 were found to exhibit colossal thermopower (S) values up to ~ −45000 μVK-1 and record high power factors up to 2300 μWK−2 cm−1 at 12 K...... enhanced thermoelectric performance. Herein, FeSb2 films were produced on silica substrates in a low-pressure Ar environment by a pulsed Nd:YAG laser at 355 nm. The effect of growth parameters, such as substrate temperature, Ar pressure, incident fluence and growth time, on the PLD growth of FeSb2...

  1. Carbon dioxide and water adsorption on highly epitaxial Delafossite CuFeO2 thin film

    Science.gov (United States)

    Rojas, S.; Joshi, T.; Borisov, P.; Sarabia, M.; Lederman, D.; Cabrera, A. L.

    2015-03-01

    Thermal programmed desorption (TPD) of CO2 and H2O from a 200 nm thick CuFeO2 Delafossite surface was performed in a standard UHV chamber, The CuFeO2 thin film grown using Pulsed Laser Deposition (PLD) over an Al2O3 (0001) substrate with controlled O2 atmosphere resulted with highly epitaxial crystal structure. The adsorption/desorption of CO2 and H2O process was also monitored with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Our results revealed that carbon dioxide interacts with CuFeO2 forming Fe carbonates compounds on its surface. Hydroxides were also formed on the surface due to water presence. Using TPD data, Arrhenius plots for CO2 and water desorption were done and activation energy for desorption was obtained. Funds FONDECyT 1130372; Thanks to P. Ferrari.

  2. Near infrared to ultraviolet optical properties of bulk single crystal and nanocrystal thin film iron pyrite

    Science.gov (United States)

    Subedi, Indra; Bhandari, Khagendra P.; Ellingson, Randall J.; Podraza, Nikolas J.

    2016-07-01

    We report optical properties of iron pyrite (FeS2) determined from ex situ spectroscopic ellipsometry measurements made on both a commercially available bulk single crystal and nanocrystalline thin film over a spectral range of 0.735-5.887 eV. The complex dielectric function, ɛ (E) = ɛ 1 (E) + iɛ 2 (E), spectra have been determined by fitting a layered parametric model to the ellipsometric measurements. Spectra in ɛ are modeled using a Kramers-Kronig consistent critical point parabolic band model involving seven critical points for the bulk single crystal and four critical points for the nanocrystalline film. Absorption coefficient spectra for both types of samples are also determined from ɛ. Critical point features in the nanocrystalline films are broader, have lower amplitude and lower energy critical points detected having a small blue shift when compared to the single crystal sample.

  3. PENGARUH PENAMBAHAN NiO TERHADAP KARAKTERISTIK KERAMIK FILM TEBAL Fe2O3 UNTUK SENSOR GAS ASETON

    Directory of Open Access Journals (Sweden)

    E. Suhendi

    2012-12-01

    Full Text Available Pembuatan keramik film tebal Fe2O3-NiO telah dilakukan dengan menggunakan Fe2O3 lokal sebagai bahan dasar untuk sensor gas aseton.  Serbuk Fe2O3 dicampur dengan serbuk NiO dengan konsentrasi 0, 10 dan 50% mol secara homogen. Serbuk campuran kemudian dicampur dengan organic vehicle (OV terbuat dari campuran terpineol dan etil selulose dengan komposisi 75% berat serbuk campuran dan 25% berat OV dan diaduk membentuk pasta. Pasta dilapiskan di atas substrat alumina dengan metode screen printing lalu dibakar pada suhu 900oC selama 90 menit hingga membentuk keramik film tebal. Film tebal dianalisis dengan difraksi sinar-x (XRD dan mikroskop elektron (SEM. Resistansi listrik keramik film tebal diukur pada berbagai suhu di ruangan berisi udara dan berisi gas aseton. Karakterisasi XRD menunjukkan bahwa struktur kristal yang terbentuk adalah Fe2O3 hematit dan NiFe2O4 kubik spinel sebagai fase kedua untuk penambahan konsentrasi NiO 10% dan 50%. Penambahan NiO diketahui memperkecil ukuran butir film tebal Fe2O3 dan meningkatkan resistansi listriknya. Keramik film tebal yang dibuat sensitif terhadap gas aseton.Fabrication of thick film Fe2O3-NiO ceramics for acetone gas sensor has been carried out using local Fe2O3as raw material.  The Fe2O3 powder was mixed with NiO powder homogeneously with NiO concentration of 0, 10 and 50 mole %. The mixed powder was then mixed with organic vehicle (OV made of alpha terpineol and ethyl cellulose with composition of 75 weight % mixed powder and 25 weight % OV forming a paste. The paste was coated on alumina substrates by screen printing method, then fired at 900oC for 90 minutes to produce thick film ceramics. The thick film was analyzed using x-ray diffraction (XRD and scanning electron microscope (SEM. Resistance of the thick films was measured at different temperatures in chamber containing air and containing acetone gas. XRD characterization showed that the crystal structures are hematite Fe2O3 and NiFe2O4 cubic

  4. Low Gilbert damping in Co2FeSi and Fe2CoSi films

    Science.gov (United States)

    Sterwerf, Christian; Paul, Soumalya; Khodadadi, Behrouz; Meinert, Markus; Schmalhorst, Jan-Michael; Buchmeier, Mathias; Mewes, Claudia K. A.; Mewes, Tim; Reiss, Günter

    2016-08-01

    Thin highly textured Fe1+xCo2-xSi (0 ≤ x ≤ 1) films were prepared on MgO (001) substrates by magnetron co-sputtering. Magneto-optic Kerr effect (MOKE) and ferromagnetic resonance (FMR) measurements were used to investigate the composition dependence of the magnetization, the magnetic anisotropy, the gyromagnetic ratio, and the relaxation of the films. Both MOKE and FMR measurements reveal a pronounced fourfold anisotropy for all films. In addition, we found a strong influence of the stoichiometry on the anisotropy as the cubic anisotropy strongly increases with increasing Fe concentration. The gyromagnetic ratio is only weakly dependent on the composition. We find low Gilbert damping parameters for all films with values down to 0.0012 ±0.00010.0007 for Fe1.75Co1.25Si. The effective damping parameter for Co2FeSi is found to be 0.0018 ±0.00040.0034 . We also find a pronounced anisotropic relaxation, which indicates significant contributions of two-magnon scattering processes that is strongest along the easy axes of the films. This makes thin Fe1+xCo2-xSi films ideal materials for the application in spin transfer-torque magnetic RAM (STT-MRAM) devices.

  5. Development of FeNiMoB thin film materials for microfabricated magnetoelastic sensors

    KAUST Repository

    Liang, Cai

    2012-12-07

    MetglasTM 2826MB foils of 25–30 μm thickness with the composition of Fe40Ni38Mo4B18 have been used for magnetoelastic sensors in various applications over many years. This work is directed at the investigation of ∼3 μm thick iron-nickel-molybdenum-boron (FeNiMoB) thin films that are intended for integrated microsystems. The films are deposited on Si substrate by co-sputtering of iron-nickel (FeNi), molybdenum(Mo), and boron (B) targets. The results show that dopants of Mo and B can significantly change the microstructure and magnetic properties of FeNi materials. When FeNi is doped with only Mo its crystal structure changes from polycrystalline to amorphous with the increase of dopant concentration; the transition point is found at about 10 at. % of Mo content. A significant change in anisotropic magneticproperties of FeNi is also observed as the Modopant level increases. The coercivity of FeNi filmsdoped with Mo decreases to a value less than one third of the value without dopant.Doping the FeNi with B together with Mo considerably decreases the value of coercivity and the out-of-plane magnetic anisotropyproperties, and it also greatly changes the microstructure of the material. In addition, doping B to FeNiMo remarkably reduces the remanence of the material. The filmmaterial that is fabricated using an optimized process is magnetically as soft as amorphous MetglasTM 2826MB with a coercivity of less than 40 Am−1. The findings of this study provide us a better understanding of the effects of the compositions and microstructure of FeNiMoB thin filmmaterials on their magnetic properties.

  6. Large remanent polarization in multiferroic NdFeO3-PbTiO3 thin film

    Science.gov (United States)

    Zhao, Hanqing; Peng, Xin; Zhang, Linxing; Chen, Jun; Yan, Wensheng; Xing, Xianran

    2013-08-01

    The single phase 0.1NdFeO3-0.9PbTiO3 thin film was fabricated on Pt(111)/Ti/SiO2/Si substrate by a sol-gel route. High energy synchrotron radiation glancing incidence X-ray diffraction and conventional X-ray diffraction were employed to determine the phase structure and crystal orientation. Large remanent polarization (2Pr ≈ 85 μC cm-2) was obtained by ferroelectric hysteresis loop and positive up negative down measurements. The oxidation state of Fe element in the film was investigated by X-ray photoelectron spectroscopy and X-ray absorption spectra methods. The results showed the coexistence of Fe2+ and Fe3+ ions with existence of oxygen vacancies. Weak magnetism (˜11 emu/cc) and obvious magnetoelectric coupling were observed in this multiferroic film.

  7. Growth of Hydroxyapatite Crystal in the Presence of Origanic Film

    Institute of Scientific and Technical Information of China (English)

    Yong LIU; Suping HUANG; Xiaohong DAN; Kechao ZHOU

    2004-01-01

    The growth of hydroxyapatite (Hap) crystal in the presence of hexadecylamine was investigated. Due to its high polarity and high charge density, the organic film could increase the ion supersaturation on its surface. Therefore the growth of pure Hap crystals was accelerated. Moreover, the positive headgroups of the organic film could act as recognized nucleation sites and orient the growth of Hap crystals along thedirection.

  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. Magnetoelectric Fe2TeO6 thin films.

    Science.gov (United States)

    Wang, Junlei; Santana, Juan A Colón; Wu, Ning; Karunakaran, Chithra; Wang, Jian; Dowben, Peter A; Binek, Christian

    2014-02-05

    We demonstrate that Fe2TeO6 is a magnetoelectric antiferromagnet with voltage-controllable boundary magnetization. This provides experimental evidence of the theoretical prediction that boundary magnetization is a universal property of magnetoelectric antiferromagnets including boundary magnetization at a surface orthogonal to the polar direction. Highly (110) textured Fe2TeO6 thin films were grown by pulsed laser deposition, terminating in Te-O at the (110) surface due to a surface reconstruction. Magnetic dc susceptibility measurements of both Fe2TeO6 powder and thin film samples confirm antiferromagnetic long-range order. Finally, measurements of x-ray magnetic circular dichroism combined with photoemission electron microscopy (XMCD-PEEM) provide a lower bound to the spin and angular magnetic moment of the surface Fe ions.

  10. Nanocrystalline Pd:NiFe{sub 2}O{sub 4} thin films: A selective ethanol gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita, E-mail: smb.agc@gmail.com

    2016-10-15

    In this work, Pd:NiFe{sub 2}O{sub 4} thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe{sub 2}O{sub 4} thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost. - Highlights: • Ethanol gas sensors based on Pd:NiFe{sub 2}O{sub 4} nanoparticle thin film were fabricated. • Pd incorporation in NiFe{sub 2}O{sub 4} matrix inhibits grain growth. • The sensors were more selective to ethanol gas. • Sensors exhibited fast response and recovery when doped with palladium. • Pd:NiFe{sub 2}O{sub 4} thin film sensor displays excellent long–term stability.

  11. Fe nanoparticles embedded in MgO crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shalimov, Artem; Potzger, Kay; Talut, Georg; Reuther, Helfried; Zhou, Shengqiang; Baehtz, Carsten; Fassbender, Juergen [Forschungszentrum Dresden-Rossendorf, Bautzner Landstrasse 128, 01328 Dresden (Germany); Geiger, Dorin; Lichte, Hannes [Technical University, Dresden (Germany); Misiuk, Andrzej [Institute of Electron Technology, Warsaw (Poland); Stromberg, Frank [Universitaet Duisburg-Essen (Germany)

    2009-07-01

    Iron nanoparticles embedded in MgO crystals were synthesized by Fe{sup +} ion implantation at an energy of 100 keV and varying fluences from 3.10{sup 16} to 3.10{sup 17} cm{sup -2}. Investigations of structural and magnetic properties of Fe nanoparticles have been performed using magnetometry, X-ray diffraction, transmission electron microscopy and Moessbauer spectroscopy, as well as by theoretical Preisach modeling of bistable magnetic systems. It has been found that {alpha}- and {gamma}-Fe nanoparticles are formed for all fluences. The content of the {alpha}-Fe phase increases at higher fluences and after annealing. The influence of post-implantation annealing at 800 C in vacuum and under enhanced up to 10 kbar hydrostatic pressure in argon atmosphere on the formation of nanoparticles has been analyzed.

  12. Microstructure and AMR Properties of Permalloy Films Sputtered on (Ni0.81Fe0.19)0.66Cr0.34 Buffer

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-fei; PENG Zi-long; LIAO Hong-wei; LI Zuo-yi

    2004-01-01

    ( Ni0.81 Fe0.19 )0.66Cr0.34 has a high resistivity and a crystal structure close to that of Ni0.81Fe0.19. The electrical and X-ray diffraction measurements prove that a thin NiFeCr seed layer induces a well(111)-oriented Ni0.81Fe0.19 film. Post-annealing treatment improves the magnetic properties of (Ni0.81 Fe0.19)0.66Cr0.34(45A)/Ni0.81Fe0.19(150A)/Ta(55A)thin film prepared under a deposition field , whereas the inter-diffu-sion of NiFe/ Ta deteriorates the magnetoresistance properties of the film.

  13. Crystallization kinetics of amorphous aluminum-tungsten thin films

    Energy Technology Data Exchange (ETDEWEB)

    Car, T.; Radic, N. [Rugjer Boskovic Inst., Zagreb (Croatia). Div. of Mater. Sci.; Ivkov, J. [Institute of Physics, Bijenicka 46, P.O.B. 304, HR-10000 Zagreb (Croatia); Babic, E.; Tonejc, A. [Faculty of Sciences, Physics Department, Bijenicka 32, P.O.B. 162, HR-10000 Zagreb (Croatia)

    1999-01-01

    Crystallization kinetics of the amorphous Al-W thin films under non-isothermal conditions was examined by continuous in situ electrical resistance measurements in vacuum. The estimated crystallization temperature of amorphous films in the composition series of the Al{sub 82}W{sub 18} to Al{sub 62}W{sub 38} compounds ranged from 800 K to 920 K. The activation energy for the crystallization and the Avrami exponent were determined. The results indicated that the crystallization mechanism in films with higher tungsten content was a diffusion-controlled process, whereas in films with the composition similar to the stoichiometric compound (Al{sub 4}W), the interface-controlled crystallization probably occurred. (orig.) With 4 figs., 1 tab., 26 refs.

  14. Tailoring magnetic frustration in strained epitaxial FeRh films

    Science.gov (United States)

    Witte, Ralf; Kruk, Robert; Gruner, Markus E.; Brand, Richard A.; Wang, Di; Schlabach, Sabine; Beck, Andre; Provenzano, Virgil; Pentcheva, Rossitza; Wende, Heiko; Hahn, Horst

    2016-03-01

    We report on a strain-induced martensitic transformation, accompanied by a suppression of magnetic order in epitaxial films of chemically disordered FeRh. X-ray diffraction, transmission electron microscopy, and electronic structure calculations reveal that the lowering of symmetry (from cubic to tetragonal) imposed by the epitaxial relation leads to a further, unexpected, tetragonal-to-orthorhombic transition, triggered by a band-Jahn-Teller-type lattice instability. The collapse of magnetic order is a direct consequence of this structural change, which upsets the subtle balance between ferromagnetic nearest-neighbor interactions arising from Fe-Rh hybridization and frustrated antiferromagnetic coupling among localized Fe moments at larger distances.

  15. Superconductivity and Properties of FeTeOx Films

    Energy Technology Data Exchange (ETDEWEB)

    D Telesca; j Budnick; B Sinkovic; R Ramprasad; B Wells

    2011-12-31

    Films of the parent compound FeTe can be made superconducting via the addition of interstitial oxygen. The process is reversible. We have characterized the new superconductors with a variety of experiments. X-ray diffraction shows that the superconductor has the same overall structure but a small lattice constant change compared to pure FeTe. X-ray absorption shows that superconducting FeTeO{sub x} has a nominal valence of 3+. DFT calculations show the most likely position for interstitial oxygen and confirm that such oxygen incorporation does not produce a large change in structure.

  16. 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.

  17. 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.

  18. Pulsed laser deposition growth of FeSb2 films for thermoelectric applications

    DEFF Research Database (Denmark)

    Sun, Ye; Canulescu, Stela; Sun, Peijie

    2011-01-01

    FeSb2 films were produced in a low-pressure Ar environment by pulsed laser deposition at 355 nm. The influence of growth parameters such as substrate temperature, Ar pressure and deposition time on the growth of FeSb2 films was studied. Nearly phase-pure FeSb2 films with thicknesses of 100–400 nm...... properties of FeSb2 films if they are to eventually reach thermoelectric applications at cryogenic temperatures....

  19. Growth of ultra-thin FeO(100) films on Ag(100): A combined XPS, LEED and CEMS study

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, G.J.P., E-mail: guilafis@gmail.com [Department of Physics, Penn State University, University Park, Pennsylvania 16802 (United States); Depto. de Física, ICEx, Universidade Federal de Minas Gerais, CP702 Belo Horizonte - MG (Brazil); Paniago, R.; Pfannes, H.-D. [Depto. de Física, ICEx, Universidade Federal de Minas Gerais, CP702 Belo Horizonte - MG (Brazil)

    2014-01-15

    The production and characterization of ultra-thin iron oxide films grown on an atomically clean Ag(100) surface by molecular beam epitaxy (MBE) is presented. The goal of this work was to prepare ultra-thin FeO(100) with excellent crystallographic quality. The films were prepared with high purity {sup 57}Fe and O{sub 2} and afterwards analyzed in situ by means of Low Energy Electron Diffraction (LEED), X-Ray Photoelectron Spectroscopy (XPS) and Conversion Electron Mössbauer Spectroscopy (CEMS). During preparation the evaporation rate, the O{sub 2} partial pressure, film thickness and annealing procedures were varied. The analysis of the various samples showed that in general a mixture of FeO and Fe{sub 3}O{sub 4} phases is obtained. We determined the best conditions to produce the desired oxide (FeO). Besides the paramagnetic phase, the antiferromagnetic phase of the FeO films was characterized by low temperature Mössbauer spectra. - Highlights: • Highly ordered iron oxide ultra-thin film was grown on Ag(100) single crystal. • The samples were submitted to annealing at various temperatures. • The changes in the iron oxide phases were checked by LEED, XPS and CEMS. • The best conditions to prepare the wüstite and magnetite phases were determined.

  20. Chitosan-Assisted Crystallization and Film Forming of Perovskite Crystals through Biomineralization.

    Science.gov (United States)

    Yang, Yang; Sun, Chen; Yip, Hin-Lap; Sun, Runcang; Wang, Xiaohui

    2016-03-18

    Biomimetic mineralization is a powerful approach for the synthesis of advanced composite materials with hierarchical organization and controlled structure. Herein, chitosan was introduced into a perovskite precursor solution as a biopolymer additive to control the crystallization and to improve the morphology and film-forming properties of a perovskite film by way of biomineralization. The biopolymer additive was able to control the size and morphology of the perovskite crystals and helped to form smooth films. The mechanism of chitosan-mediated nucleation and growth of the perovskite crystals was explored. As a possible application, the chitosan-perovskite composite film was introduced into a planar heterojunction solar cell and increased power conversion efficiency relative to that observed for the pristine perovskite film was achieved. The biomimetic mineralization method proposed in this study provides an alternative way of preparing perovskite crystals with well-controlled morphology and properties and extends the applications of perovskite crystals in photoelectronic fields, including planar-heterojunction solar cells.

  1. Spin Seebeck effect in insulating epitaxial γ−Fe2O3 thin films

    Directory of Open Access Journals (Sweden)

    P. Jiménez-Cavero

    2017-02-01

    Full Text Available We report the fabrication of high crystal quality epitaxial thin films of maghemite (γ−Fe2O3, a classic ferrimagnetic insulating iron oxide. Spin Seebeck effect (SSE measurements in γ−Fe2O3/Pt bilayers as a function of sample preparation conditions and temperature yield a SSE coefficient of 0.5(1 μV/K at room temperature. Dependence on temperature allows us to estimate the magnon diffusion length in maghemite to be in the range of tens of nanometers, in good agreement with that of conducting iron oxide magnetite (Fe3O4, establishing the relevance of spin currents of magnonic origin in magnetic iron oxides.

  2. {sup 57}Fe Moessbauer probe of spin crossover thin films on a bio-membrane

    Energy Technology Data Exchange (ETDEWEB)

    Naik, Anil D.; Garcia, Yann, E-mail: yann.garcia@uclouvain.be [Universite Catholique de Louvain, Institute of Condensed Matter and Nanosciences (Belgium)

    2012-03-15

    An illustrious complex [Fe(ptz){sub 6}](BF{sub 4}){sub 2} (ptz = 1-propyl-tetrazole) (1) which was produced in the form of submicron crystals and thin film on Allium cepa membrane was probed by {sup 57}Fe Mossbauer spectroscopy in order to follow its intrinsic spin crossover. In addition to a weak signal that corresponds to neat SCO compound significant amount of other iron compounds are found that could have morphed from 1 due to specific host-guest interaction on the lipid-bilayer of bio-membrane. Further complimentary information about biogenic role of membrane, was obtained from variable temperature Mossbauer spectroscopy on a {approx}5% enriched [{sup 57}Fe(H{sub 2}O){sub 6}](BF{sub 4}){sub 2} salt on this membrane.

  3. 57 Fe Mössbauer probe of spin crossover thin films on a bio-membrane

    Science.gov (United States)

    Naik, Anil D.; Garcia, Yann

    2012-03-01

    An illustrious complex [Fe(ptz)6](BF4)2 (ptz = 1-propyl-tetrazole) ( 1) which was produced in the form of submicron crystals and thin film on Allium cepa membrane was probed by 57Fe Mossbauer spectroscopy in order to follow its intrinsic spin crossover. In addition to a weak signal that corresponds to neat SCO compound significant amount of other iron compounds are found that could have morphed from 1 due to specific host-guest interaction on the lipid-bilayer of bio-membrane. Further complimentary information about biogenic role of membrane, was obtained from variable temperature Mossbauer spectroscopy on a ~5% enriched [57Fe(H2O)6](BF4)2 salt on this membrane.

  4. 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.

  5. The structure and surface energy of Ni{sub 80}Fe{sub 20} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yuan-Tsung, E-mail: ytchen@yuntech.edu.tw; Chen, Chin-Wu; Wu, Te-Ho

    2015-10-01

    Highlights: • X-ray diffraction patterns indicated NiFe thin films exhibited a face-centred cubic (FCC) structural. • NiFe films were more crystalline after postannealing treatment than they were after RT treatment. • NiFe films formed a contact angle of <90°, which indicated that the NiFe films were hydrophilic. • The surface energy was associated with the crystallinity of the thin films. • NiFe thin films exhibit low surface-energy characteristics that can produce a self-cleaning effect. - Abstract: In this study, NiFe thin films were deposited on a glass substrate at room temperature (RT) or postannealed at 150 and 250 °C for 1 h; the Ni{sub 80}Fe{sub 20} films were 300–1500 Å thick. The structure, surface energy, and average contact angle properties of the NiFe thin films were investigated. X-ray diffraction (XRD) results demonstrated that the NiFe thin films exhibited a face-centred cubic (FCC) structural state. The XRD results also revealed that the NiFe films were more crystalline after post-annealing treatment than they were after RT treatment alone, suggesting that the NiFe crystalline structure exhibited FCC (1 1 1) texturing. The NiFe films formed a contact angle of <90° with the test liquids water and diiodomethane, which indicated that the NiFe films were hydrophilic. The surface energy of the NiFe thin films decreased when post-annealing treatment was used and their thickness was increased from 60.4 to 47.9 mJ/mm{sup 2}, suggesting that the surface energy was associated with the crystallinity of the thin films. Therefore, these NiFe thin films exhibit low surface-energy characteristics that can produce a self-cleaning effect.

  6. Magnetization dynamics in rare earth doped NiFe films

    Energy Technology Data Exchange (ETDEWEB)

    Kiessling, Matthias; Woltersdorf, Georg; Back, Christian [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D- 93040 Regensburg (Germany); Thiele, Jan-Ulrich; Schabes, Manfred [Hitachi Global Storage Technologies, 3403 Yerba Buena Road, San Jose, CA 95135 (United States)

    2007-07-01

    The influence of rare earth dopants on the damping parameter and the resulting possibility to control this parameter were investigated. In our experiments NiFe films were doped with Dysprosium, Holmium, Terbium, and Gadolinium. The magnetization dynamics of these rare earth doped films was mainly studied by means of ferromagnetic resonance (FMR) and network-analyzer ferromagnetic resonance. It is demonstrated that the doping of a NiFe film by a small amount of rare earth elements (Holmium, Terbium and Dysprosium) greatly effects its magnetic relaxation rate. This additional damping is proportional to the doping level. Compared to the pure NiFe film it is possible to increase the damping parameter of the magnetic film by two orders of magnitude. On the other hand Gadolinium as a dopant has no influence on the damping parameter. For small dopant concentrations the in and out-of-plane FMR measurements at various frequencies can be well described by the same damping parameter. This is expected for the Gilbert damping term in the equation of motion. Therefore the increased damping can be attributed to an increased rate of transfer of angular momentum from the spin system to the lattice.

  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. Rapid thermal annealing of FePt and FePt/Cu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Brombacher, Christoph

    2011-01-10

    Chemically ordered FePt is one of the most promising materials to reach the ultimate limitations in storage density of future magnetic recording devices due to its high uniaxial magnetocrystalline anisotropy and a corrosion resistance superior to rare-earth based magnets. In this study, FePt and FePt/Cu bilayers have been sputter deposited at room temperature onto thermally oxidized silicon wafers, glass substrates and self-assembled arrays of spherical SiO{sub 2} particles with diameters down to 10 nm. Millisecond flash lamp annealing, as well as conventional rapid thermal annealing was employed to induce the phase transformation from the chemically disordered A1 phase into the chemically ordered L1{sub 0} phase. The influence of the annealing temperature, annealing time and the film thickness on the ordering transformation and (001) texture evolution of FePt films with near equiatomic composition was studied. Whereas flash lamp annealed FePt films exhibit a polycrystalline morphology with high chemical L1{sub 0} order, rapid thermal annealing can lead to the formation of chemically ordered FePt films with (001) texture on amorphous SiO{sub 2}/Si substrates. The resultant high perpendicular magnetic anisotropy and large coercivities up to 40 kOe are demonstrated. Simultaneously to the ordering transformation, rapid thermal annealing to temperatures exceeding 600 C leads to a break up of the continuous FePt film into separated islands. This dewetting behavior was utilized to create regular arrays of FePt nanostructures on SiO{sub 2} particle templates with periods down to 50 nm. The addition of Cu improves the (001) texture formation and chemical ordering for annealing temperatures T{sub a} {<=}600 C. In addition, the magnetic anisotropy and the coercivity of the ternary FePtCu alloy can be effectively tailored by adjusting the Cu content. The prospects of FePtCu based exchange spring media, as well as the magnetic properties of FePtCu nanostructures fabricated

  9. Abnormal effect of substrate temperature on perpendicular magnetic anisotropy in sputter-deposited NdFeCo films on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Liuniu, E-mail: lntong@ahut.edu.cn [Anhui Key Laboratory of Metal Materials and Processing, School of Materials Science and Engineering, Anhui University of Technology, Ma-An-Shan, 243002 Anhui (China); Deng, Peng [Anhui Key Laboratory of Metal Materials and Processing, School of Materials Science and Engineering, Anhui University of Technology, Ma-An-Shan, 243002 Anhui (China); He, Xian-Mei [School of Mathematics and Physics, Anhui University of Technology, Ma-An-Shan, 243002 Anhui (China); Li, Tingting [Anhui Key Laboratory of Metal Materials and Processing, School of Materials Science and Engineering, Anhui University of Technology, Ma-An-Shan, 243002 Anhui (China)

    2014-07-01

    The effect of substrate temperature on the perpendicular magnetic anisotropy (PMA) in sputtered NdFeCo films on Si(111) has been studied. A strong PMA is observed in the NdFeCo films deposited at 310 °C, while the room temperature (RT) deposited films show an in-plane dominated anisotropy. The microstructure reveals a stratified microstructure along film thickness due to diffusion occurring at Si(111)/NdFeCo interface of the films deposited at 310 °C. Nd{sub 2}(FeCo){sub 17} nano-crystals and Nd{sub 2}(FeCo){sub 14}Si{sub 3} and/or Nd{sub 6}(FeCo){sub 13}Si intermetallic compounds in nano-size appear in the films deposited at 310 °C, while the RT deposited NdFeCo films are in amorphous state. Annealing at 300 °C results in atomic relaxation and thus ordering of the stripe domains. The distinguishing dependence of the micro/magnetic structure and magnetic characteristics of the NdFeCo films on substrate temperature and annealing temperature is presented. It is concluded that the strong PMA is mainly from the magnetoelastic anisotropy caused by the induced interfacial stress due to the opposite thermal expansion behavior between the NdFeCo layer and Si-doped interfacial layer. - Highlights: • NdFeCo films were deposited on Si substrate at 25 and 310 °C, respectively. • The films deposited at 310 °C show a large perpendicular magnetic anisotropy (PMA). • The films deposited at 25 °C have an in-plane dominated anisotropy. • The PMA is mainly from the magnetoelastic anisotropy induced by interfacial stress.

  10. Spectral selectivity of 3D magnetophotonic crystal film fabricated from single butterfly wing scales

    Science.gov (United States)

    Peng, Wenhong; Zhu, Shenmin; Zhang, Wang; Yang, Qingqing; Zhang, Di; Chen, Zhixin

    2014-05-01

    3D magnetophotonic crystal (3D-MPC) film is an excellent platform for tailoring the magneto-optical response of magnetic materials. However, its fabrication is a great challenge due to the limitation of commonly used artificial synthesis methods. Inspired by the unique structures of biospecies, we hereby manipulate the pristine single wing scales of Morpho didius precisely and successfully fabricate Fe3O4 films with photonic structure. The synthesis strategy involves the fabrication of Fe2O3 film from a single wing scale using an improved sol-gel method followed by a subsequent reduction. The intrinsic hierarchical photonic structures as well as the anisotropic optical properties of the pristine butterfly wing scale have been retained in the obtained Fe2O3 and Fe3O4 films. When investigated under an external magnetic field, a spectral blue shift about 43 nm is observed in the designated orientation of the Fe3O4 film, which is useful for the design and creation of novel magnetic-optical modulator devices. Furthermore, these single scales can be used as building blocks to fabricate designable and more complicated assembled nano systems. This biomimetic technique combined with the variety of structures of butterfly wing scales provides an effective approach to produce magneto-photonic films with desired structure, paving a new way for theoretical research and practical applications.3D magnetophotonic crystal (3D-MPC) film is an excellent platform for tailoring the magneto-optical response of magnetic materials. However, its fabrication is a great challenge due to the limitation of commonly used artificial synthesis methods. Inspired by the unique structures of biospecies, we hereby manipulate the pristine single wing scales of Morpho didius precisely and successfully fabricate Fe3O4 films with photonic structure. The synthesis strategy involves the fabrication of Fe2O3 film from a single wing scale using an improved sol-gel method followed by a subsequent reduction

  11. Structural and textural characterization of LiFePO{sub 4} thin films prepared by pulsed laser deposition on Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Legrand, C.; Dupont, L. [Laboratoire de Reactivite et Chimie des Solides, UMR CNRS 6007, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex (France); Tang, K.; Li, H.; Huang, X.J. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Baudrin, E., E-mail: emmanuel.baudrin@u-picardie.f [Laboratoire de Reactivite et Chimie des Solides, UMR CNRS 6007, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex (France)

    2010-07-30

    LiFePO{sub 4} thin films were grown on silicon (100) substrates by pulsed laser deposition using Traditional Geometry (TG) and Off-Axis Geometry (OAG) deposition chambers. We examined and compared the structure and composition of the so formed thin films. The nails observed on the OAG-film present an amorphous 'body' and a crystallized 'head'. The Fe/P ratio determined using energy dispersive spectrometry combined with high angle annular dark field images reveals a metallic iron heart surrounded by LiFePO{sub 4} shell. On the other hand, the protuberances on TG-film are pure iron. The focused ion beam prepared cross-section of the film suggests the presence of iron particles and iron dendritic like filaments inside the LiFePO{sub 4} layer.

  12. Structure and 57Fe conversion electron M(o)ssbauer spectroscopy study of Mn-Zn ferrite nanocrystal thin films by electroless plating in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    SUN JianRong; WANG XueWen; LIU JinHong; WANG JianBo; LI FaShen

    2008-01-01

    Mn1-xZnxFe2O4 thin films with various Zn contents and of different thickness were synthesized on glass substrates directly by electroless plating in aqueous solution at 90℃ without heat treatment. The Mn-Zn ferrite films have a single spinel phase structure and well-crystallized columnar grains growing per-pendicularly to the substrates. The results of conversion electron 57Fe Mossbauer spectroscopy (CEMS) indicate that the cation distribution of Mn-xZnxFe2O4 ferrite nanocrystal thin films fabricated by elec-troless plating is different from the bulk materials' and a great quantity of Fe3+ ions are still present on A sites for x>0.5. When the Zn content of the films increases, Fe3+ ions in the films transfer from A sites to B sites and the hyperfine magnetic field reduces, suggesting that Zn2+ has strong chemical affinity towards the A sites. On the other side, with the increase of the thickness of the films, Fe3+ ions, at B sites in the spinel structure, increase and the array of magnetic moments no longer lies in the thin film plane completely. At x=0.5, Hc and Ms of Mn1-xZnxFe2O4 thin films show a minimum of 3.7 kA/m and a maximum of 419.6 kA/m, respectively.

  13. Single-crystal semiconductor films grown on foreign substrates

    Science.gov (United States)

    Vohl, P.

    1966-01-01

    Intermediate alloy formed between foreign substrates and semiconductor material enable the growth of single crystal semiconductor films on the alloy layer. The melted film must not ball up on the surface of the substrate and neither chemically react nor alloy with the intermediate alloy formed on the substrate.

  14. Growth of binary Ni–Fe films: Characterisations at low and high potential levels

    Energy Technology Data Exchange (ETDEWEB)

    Kuru, Hilal, E-mail: htopcu@balikesir.edu.tr [Physics Department, Science and Literature Faculty, Balikesir Universitesi, Fen Edebiyat Fakultesi, Fizik Bolumu, Cagis Yerleskesi, 10145 Balikesir (Turkey); Kockar, Hakan, E-mail: hkockar@balikesir.edu.tr [Physics Department, Science and Literature Faculty, Balikesir Universitesi, Fen Edebiyat Fakultesi, Fizik Bolumu, Cagis Yerleskesi, 10145 Balikesir (Turkey); Alper, Mursel, E-mail: malper@uludag.edu.tr [Physics Department, Science and Literature Faculty, Uludag Universitesi, Fen Edebiyat Fakultesi, Fizik Bolumu, Gorukle, 16059 Bursa (Turkey); Karaagac, Oznur, E-mail: karaagac@balikesir.edu.tr [Physics Department, Science and Literature Faculty, Balikesir Universitesi, Fen Edebiyat Fakultesi, Fizik Bolumu, Cagis Yerleskesi, 10145 Balikesir (Turkey)

    2015-03-01

    Binary Ni–Fe films relating their magnetoresistance and magnetic properties with crystal structure and surface morphology, and the corresponding film composition were investigated at low and high deposition potentials. Based on the results obtained from a cyclic voltammetry curve, a potential region between −1.3 V and −1.8 V was selected, and the current–time transients were recorded to control the proper film growth. The Ni–Fe films were potentiostatically electrodeposited on polycrystalline titanium substrates at low (−1.3 V) and high (−1.8 V) deposition potential. The data from the energy dispersive X-ray spectrometry and the inductively coupled plasma atomic emission spectroscopy demonstrated that the Ni and Fe content in the films varied as the potential changed. The magnetotransport properties and magnetic characteristics studied by a vibrating sample magnetometer (VSM) were observed to be affected by the deposition potentials. All films were also noted to exhibit anisotropic magnetoresistance behaviour. At low potential, the magnitude of the longitudinal magnetoresistance (LMR) was high (3.93%) and that of the transverse magnetoresistance (TMR) was low (3.49%) while for the film at high potential the LMR (2.76%) and the TMR (3.66%) magnitudes were obtained. Magnetization measurements by VSM revealed that the saturation magnetization, M{sub s} was 779 emu/cm{sup 3} and saturation field, H{sub s} was 142 Oe at low potential while for the films deposited at high potential the M{sub s} and H{sub s} were 749 emu/cm{sup 3} and 262 Oe, respectively. However, the coercivities in the films were found to be around 4.5 Oe, regardless of the potential. Also, the magnetic easy axis was found to be in the film plane for all samples. The structural analysis of the films was carried out using the X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. To XRD analysis, all films have a strong (111) texture of face-centred cubic structure and

  15. Effects of annealing temperature on the magnetoresistance in Ta/NiFe/Ta films by ZnO intercalations

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Lei, E-mail: Lding@hainu.edu.cn [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); Yu, Guang-hua; Zhang, Min; Zhao, Chong-jun; Teng, Jiao [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Xiang, Dao-ping [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China)

    2015-09-01

    Zinc oxide (ZnO) exhibiting many superior physical properties was inserted into the Ta/NiFe/Ta films as nano-oxide intercalations. Different annealing temperatures and ZnO thickness significantly affected the magnetoresistance (MR) in NiFe films. The 4-nm thick ZnO film annealed at 200 °C had a MR of 2.41%, which was more than 70% higher than that of the 1-nm thick ZnO annealed film (MR=1.40%). However, the further increase in annealing temperature to 300 °C rapidly deteriorated the MR performance of the films. Diffusion and interface reactions occur between the crystal ZnO and the adjacent NiFe layer. Lower-temperature annealing improved the interface, increasing the specular reflection of spin-polarized electrons to some extent. However, higher-temperature annealing induced severe diffusion and interface reactions, which led to a sharp decline in MR performance. - Highlights: • Combining NiFe with ZnO, thereby producing NiFe/ZnO interfaces. • Investigating the effects of annealing temperatures on the magnetoresistance. • Explaining the corresponding relationship between MR and microstructure.

  16. Orientation control and thermoelectric properties of FeSb2 films

    DEFF Research Database (Denmark)

    Sun, Ye; Zhang, Eryun; Johnsen, Simon

    2010-01-01

    lang0 0 2rang-textured FeSb2 films by employing a pre-deposited FeSb2 thin-film layer as template. The in-plane thermoelectric properties of FeSb2 films with different orientations were studied and compared. The anisotropy of FeSb2 is shown to have an important effect on the transport properties of FeSb......2 films. Orientation control of the FeSb2 films could be significant for their property optimization and thus highlight their application potential.......FeSb2 has a high potential for technological applications due to its colossal thermoelectric power, giant carrier mobility and large magnetoresistance. Earlier, growth of lang1 0 1rang-textured FeSb2 films on quartz (0 0 0 1) substrates has been reported. Here magnetron sputtering is used to obtain...

  17. Preparation and characterization of BiFeO3 thin films by the LPD on OH-functionalized organic SAMs

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    BiFeO3 (BFO) thin films were grown on OH-functionalized organic self-assembled monolayers (SAMs) via liquid-phase deposition (LPD) method at a temperature below 100°C. The BiFeO3 thin films were induced to synthesize on the OH-functionalized organic OTS monolayers prepared on hydroxylated glass substrate by self-assembling technique. The hydrophilic characteristic of the as-prepared OTS-SAMs was measured by contact angle tester. The crystal phase composition, microstructure and topography of the as-synthesized BFO thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and atomic force microscope (AFM), respectively. Results show that compact and homogeneous BFO thin films can be formed on the OH-functionalized SAMs at low temperature.

  18. Fabrication and Characterization of Colloidal Crystal Thin Films

    Science.gov (United States)

    Rodriguez, I.; Ramiro-Manzano, F.; Meseguer, F.; Bonet, E.

    2011-01-01

    We present a laboratory experiment that allows undergraduate or graduate students to get introduced to colloidal crystal research concepts in an interesting way. Moreover, such experiments and studies can also be useful in the field of crystallography or solid-state physics. The work concerns the growth of colloidal crystal thin films obtained…

  19. Fabrication and Characterization of Colloidal Crystal Thin Films

    Science.gov (United States)

    Rodriguez, I.; Ramiro-Manzano, F.; Meseguer, F.; Bonet, E.

    2011-01-01

    We present a laboratory experiment that allows undergraduate or graduate students to get introduced to colloidal crystal research concepts in an interesting way. Moreover, such experiments and studies can also be useful in the field of crystallography or solid-state physics. The work concerns the growth of colloidal crystal thin films obtained…

  20. Liquid crystal film development for plasma mirrors and waveplates

    Science.gov (United States)

    Cochran, G. E.; Poole, P. L.; Willis, C.; Hanna, R. J.; Pytel, K.; Sullivan, K. S.; Andereck, C. D.; Schumacher, D. W.

    2015-11-01

    Many laser-plasma phenomena currently under study depend critically on the quality of the pulse contrast. Costly sacrificial plasma mirrors are now commonly used to improve the temporal laser contrast before target interaction, especially for ion acceleration where high contrast is necessary to achieve interesting new mechanisms. Liquid crystal films were originally developed as variable thickness thin-film targets, and were demonstrated for this purpose in. Varying film formation parameters such as volume, temperature, and draw speed allows thickness control between 10 nm and several 10s of microns, in-situ and under vacuum. Development since that initial work has allowed large area films to be formed, several cm2 in extent, with the same thickness range. The molecular flatness of a freely suspended film renders these films excellent low-cost plasma mirrors, given appropriate formation control. Additionally, the birefringence of the liquid crystal used here permits these films to be used as large area zero-order waveplates at the appropriate thickness. Details on the current state of liquid crystal film application development, including a >1 Hz small area film formation device, will be presented. This work was performed with support from the DARPA PULSE program through a grant from AMRDEC and by the NNSA under contract DE-NA0001976.

  1. Surface and bulk crystallization of amorphous solid water films: Confirmation of "top-down" crystallization

    Science.gov (United States)

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-10-01

    The crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism was confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a "top-down" crystallization mechanism.

  2. Surface and bulk crystallization of amorphous solid water films: Confirmation of “top-down” crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-10-01

    The crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism was confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a “top-down” crystallization mechanism.

  3. Magnetization reversal of Fe ultrathin film on Cu (100)

    Institute of Scientific and Technical Information of China (English)

    He Wei; Zhan Qing-Feng; Wang De-Yong; Chen Li-Jun; Cheng Zhao-Hua

    2008-01-01

    The magnetization reversal of Fe/Cu(100) ultrathin films grown at room temperature is investigated by using an in situ magneto-optical Kerr effect polarimcter with a magnet that can rotate in a plane of incidence.There occur spin reorientation transitions from out-of-plane to in-plane magnetizations in 8 and 12 monolayers (ML) thick iron films.The coercive fields axe observed to be proportional to the reciprocal of the cosine with respect to the easy axis,suggesting that the domain-wall displacement plays a main role in the magnetization reversal process.

  4. Crystallization of amorphous Co-Nb-Zr sputtered films

    Energy Technology Data Exchange (ETDEWEB)

    Battezzati, L.; Baricco, M.; Attina, P.

    1986-08-01

    Thermal analysis results obtained with some sputtered Co-Nb-Zr alloys are presented. Microstructural determinations at some stages of the crystallization process were made with transmission electron microscopy and the results given. Crystallization occurs over a wider temperature range than for binary Co/sub 90/Zr/sub 10/ ribbons. Binary Co-Nb films crystallize in the range 750-800K, some 10 degrees below ternary films. The presence of zirconium enhances the stability of the amorphous phase. An explanation of the results is given.

  5. Large pyramid shaped single crystals of BiFeO{sub 3} by solvothermal synthesis method

    Energy Technology Data Exchange (ETDEWEB)

    Sornadurai, D.; Ravindran, T. R.; Paul, V. Thomas; Sastry, V. Sankara [Condensed Matter Physics Division, Materials Science Group, Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India); Condensed Matter Physics Division, Materials Science Group (India)

    2012-06-05

    Synthesis parameters are optimized in order to grow single crystals of multiferroic BiFeO{sub 3}. 2 to 3 mm size pyramid (tetrahedron) shaped single crystals were successfully obtained by solvothermal method. Scanning electron microscopy with EDAX confirmed the phase formation. Raman scattering spectra of bulk BiFeO3 single crystals have been measured which match well with reported spectra.

  6. Studies on confined crystallization behavior of polycaprolactone thin films

    Institute of Scientific and Technical Information of China (English)

    QIAO Congde; JIANG Shichun; JI Xiangling; AN Lijia; JIANG Bingzheng

    2007-01-01

    The confined crystallization behavior ofpolycap-rolactone (PCL) in thin and ultrathin films was studied by AFM (atomic force microscopy). It was found that the crys-talline morphology of PCL depended on the film's thickness.When the thickness is d>2Rg (radius of gyration), the polymer can crystallize into spherulites; when Rg < d< 2 Rg,a dense-branch morphology and dendrites could be found;when dcrystallization temperature and the substrate and the molecular weigbt on the crystalline mor-phology were discussed. It was shown that the crystallization of PCL in thin films is a diffusion-controlled process, and it can be explained by diffusion-limited aggregation.

  7. Magneto-thermoelectric effects in NiFe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, Maximilian

    2015-11-01

    In this thesis magneto-thermoelectric effects are investigated in a systematic way to separate the transverse spin Seebeck effect from other parasitic effects like the anomalous Nernst effect. In contrast to the first studies found in the literature, in NiFe thin films a contribution of the transverse spin Seebeck effect can be excluded. This surprising outcome was crosschecked in a variety of different sample layouts and collaborations with other universities to ensure the validity of these results. In general, this thesis solves a long time discussion about the existence of the transverse spin Seebeck effect in NiFe films and supports the importance of control measurements for the scientific community. Even if such ''negative'' results may not be the award winning ones, new discoveries should be treated with constructive criticism and be checked carefully by the scientific community.

  8. Chemical ordering at low temperatures in FePd films

    Science.gov (United States)

    Ravelosona, D.; Chappert, C.; Bernas, H.; Halley, D.; Samson, Y.; Marty, A.

    2002-05-01

    We demonstrate that, if a high degree of short range order is present in FePd disordered films, a high value of the long range order parameter S can be obtained by using postgrowth ion irradiation at very low processing temperatures. FePd films deposited monolayer by monolayer at room temperature on MgO(001) substrates exhibit a very low degree of long range order (S˜0.1) but a high degree of short range order as demonstrated by extended x-ray absorption fine structure measurements. Irradiation with 130 keV He+ ions at low fluences (2.0×1016 ions/cm2) leads to a large increase in the long range order parameter and to a large increase in perpendicular anisotropy for irradiation at substrate temperatures lower than 200 °C. This could have a great impact on the current race toward high magnetic recording density media.

  9. Structural, magnetic and optical properties of Y bFe2O4 films deposited by spin coating

    Science.gov (United States)

    Fujii, Tatsuo; Okamura, Naoya; Hashimoto, Hideki; Nakanishi, Makoto; Kano, Jun; Ikeda, Naoshi

    2016-08-01

    Rare-earth iron oxides (RFe2O4) have attracting attention as new electronic device materials because of their numerous functionalities, such as electronic ferroelectricity, ferrimagnetism, and high infrared absorption. In this paper, nearly monophasic Y bFe2O4 films were prepared on α-Al2O3(001) substrates by the spin coating method using an aqueous-based Y bFe2O4 solution. The solution was composed of a stoichiometric ratio of Y b(CH3COO)3 and Fe(NO3)3 with excess chelating agents. After heat treatment above 800 °C, well-crystallized and highly (001)-oriented Y bFe2O4 started to epitaxially form on the substrate under controlled oxygen partial pressure with H2/CO2 gas mixtures. X-ray pole figure analysis confirmed the following epitaxial relationship: Y bFe2O4[100](001)//α-Al2O3[100](001). Moreover formation of an Fe3O4 interracial layer between Y bFe2O4 and α-Al2O3 was detected by high-resolution transmission electron microscopy. Presence of the Fe3O4 interracial layer seemed to release the lattice misfit with the substrate. The Fe2+/Fe3+ ratio in the obtained Y bFe2O4 films was nearly stoichiometric and the indirect bandgap assigned to Fe2+ → Fe3+ charge transfer excitation was found to be ˜0.4 eV by optical spectroscopy. A clear magnetic transition from the paramagnetic state to the ferrimagnetic state occurred at ˜230 K.

  10. Effect of Fe doping on the microstructure and electrical properties of transparent ZnO nanocrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C.C. [Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan, ROC (China); Young, S.L., E-mail: slyoung@mail.hust.edu.tw [Department of Electronic Engineering, Hsiuping University of Science and Technology, Taichung 41280, Taiwan, ROC (China); Kung, C.Y., E-mail: cykung@dragon.nchu.edu.tw [Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan, ROC (China); Jhang, M.C. [Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan, ROC (China); Lin, C.H. [Department and Graduate School of Electrical Engineering, Hsiuping University of Science and Technology, Taichung 41280, Taiwan, ROC (China); Kao, M.C.; Chen, H.Z. [Department of Electronic Engineering, Hsiuping University of Science and Technology, Taichung 41280, Taiwan, ROC (China); Ou, C.R.; Cheng, C.C.; Lin, H.H. [Department and Graduate School of Electrical Engineering, Hsiuping University of Science and Technology, Taichung 41280, Taiwan, ROC (China)

    2013-02-01

    The transparent ZnO and Zn{sub 0.96}Fe{sub 0.04}O nanocrystalline films were deposited on the glass substrates by sol–gel method followed by repaid thermal annealing treatment. The grain size of the ZnO films was decreased by the doping of Fe. X-ray diffraction measurements of the films showed the same wurtzite hexagonal structure and preferential orientation along the c-axis. Temperature dependence resistivity showed a semiconductor transport behavior for both compositions. At high temperature region, the transport mechanism can be fitted with semiconductor behavior by Arrhenius equation, σ(T) = σ{sub 0}exp[−(E{sub a}/kT){sup m}] with m = 1. The activation energy E{sub a} is increased from 0.47 meV for pure ZnO film to 0.69 meV for Zn{sub 0.96}Fe{sub 0.04}O film obtained from equation. At low temperature region, the resistivity can be fitted well with the behavior of Mott variable range hopping, σ(T) = σ{sub h0}exp[−(T{sub 0}/T){sup n}] with n = 1/4. The results demonstrate that the crystallization and the corresponding carrier transport behavior of the Zn{sub 1−x}Fe{sub x}O films are affected by the doping of Fe in the Zn{sub 1−x}Fe{sub x}O films.

  11. Liquid crystal alignment on ZnO nanostructure films

    Science.gov (United States)

    Chung, Yueh-Feng; Chen, Mu-Zhe; Yang, Sheng-Hsiung; Jeng, Shie-Chang

    2016-03-01

    The study of liquid crystal (LC) alignment is important for fundamental researches and industrial applications. The tunable pretilt angles of liquid crystal (LC) molecules aligned on the inorganic zinc oxide (ZnO) nanostructure films with controllable surface wettability are demonstrated in this work. The ZnO nanostructure films are deposited on the ITO- glass substrates by the two-steps hydrothermal process, and their wettability can be modified by annealing. Our experimental results show that the pretilt angles of LCs on ZnO nanostructure films can be successfully adjusted over a wide range from ~90° to ~0° as the surface energy on the ZnO nanostructure films changes from ~30 to ~70 mJ/m. Finally we have applied this technique to fabricate a no-bias optically-compensated bend (OCB) LCD with ZnO nanostructure films annealed at 235 °C.

  12. Soft magnetic properties and high frequency characteristics of FeM (M = B, Hf, Zr) and pure Fe films fabricated by oblique deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chengcheng; Zhang, Chao; Wang, Fenglong; Zhao, Zhong; Jiang, Changjun; Xue, Desheng [Lanzhou University, Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou (China); Lanzhou University, Key Laboratory of Special Function Materials and Structure Design of Ministry of Education, Lanzhou (China)

    2015-09-15

    To improve the high-frequency properties of Fe-based thin films, doped and pure Fe thin films were obliquely deposited on Si (100) substrate by RF-magnetron sputtering. Vibrating sample magnetometer (VSM) measurements show obvious in-plane uniaxial magnetic anisotropy in both doped and pure Fe thin films, and enhancement effects of doping on Soft magnetic properties were also observed. Microwave permeability measurements indicate that the resonance frequency and permeability of pure Fe films are much larger than those of doped Fe thin films. Damping factors of Fe thin films deposited at different oblique angles were further investigated. (orig.)

  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. Growth and thermoelectric properties of FeSb2 films produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Sun, Ye; Canulescu, Stela; Sun, Peijie

    2011-01-01

    by ablating specifically prepared compound targets made of Fe and Sb powders in atomic ratio of 1:4. The thermoelectric transport properties of FeSb2 films were investigated. Pulsed laser deposition was demonstrated as a method for production of good-quality FeSb2 films.......Thermoelectric FeSb2 films were produced by pulsed laser deposition on silica substrates in a low-pressure Ar environment. The growth conditions for near phase-pure FeSb2 films were confirmed to be optimized at a substrate temperature of 425°C, an Ar pressure of 2 Pa, and deposition time of 3 h...

  15. Coherent Fe-rich nano-scale perovskite oxide phase in epitaxial Sr2FeMoO6 films grown on cubic and scandate substrates

    Science.gov (United States)

    Deniz, Hakan; Preziosi, Daniele; Alexe, Marin; Hesse, Dietrich

    2017-01-01

    We report the growth of high-quality epitaxial Sr2FeMoO6 (SFMO) thin films on various unconventional oxide substrates, such as TbScO3, DyScO3, and Sr2Al0.3Ga0.7TaO6 (SAGT) as well as on the most commonly used one, SrTiO3 (STO), by pulsed laser deposition. The films were found to contain a foreign nano-scale phase coherently embedded inside the SFMO film matrix. Through energy dispersive X-ray spectroscopy and scanning transmission electron microscopy, we identified the foreign phase to be Sr2-xFe1+yMo1-yO6, an off-stoichiometric derivative of the SFMO compound with Fe rich content (y ≈ 0.6) and a fairly identical crystal structure to SFMO. The films on STO and SAGT exhibited very good magnetic properties with high Curie temperature values. All the samples have fairly good conducting behavior albeit the presence of a foreign phase. Despite the relatively large number of items of the foreign phase, there is no significant deterioration in the properties of the SFMO films. We discuss in detail how magneto-transport properties are affected by the foreign phase.

  16. 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.

  17. FMR study of thin film FeGe skyrmionic material

    Science.gov (United States)

    Bhallamudi, Vidya P.; Page, Michael R.; Gallagher, James; Purser, Carola; Schulze, Joseph; Yang, Fengyuan; Hammel, P. Chris

    Magnetic Skyrmions have attracted intense interest due to their novel topological properties and the potential for energy efficient computing. Magnetic dynamics play an important part in enabling some of these functionalities. Understanding these dynamics can shed light on the interplay of the various magnetic interactions that exist in these materials and lead to a rich magnetic phase diagram, including the Skyrmion phase. We have grown phase-pure FeGe epitaxial films on Si (111) and studied them using ferromagnetic resonance (FMR). FeGe has one of the highest recorded skyrmion transition temperatures, close to room temperature, and thin films are known to further stabilize the Skyrmion phase in the magnetic field-temperature space. We have performed cavity-based single frequency FMR from liquid nitrogen to room temperature on 120 nm thick films in both in-plane and out-of-plane geometries. The resulting complex spectra are consistent with those reported in literature for the bulk material and can be understood in terms of a conical model for the magnetism. Variable temperature broadband spectroscopy and measurements on thinner films, to better identify the various magnetic phases and their dynamic behavior, are ongoing and their progress will be discussed. Funding for this research was provided by the Center for Emergent Materials: an NSF MRSEC under Award Number DMR-1420451.

  18. Multiband Effects on -FeSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic C.; Lei, H.; Graf, D.; Hu, R.; Ryu, H.; Choi, E.S.; Tozer, S.W.

    2012-03-01

    We present the upper critical fields {mu}{sub 0}H{sub c2}(T) and Hall effect in {beta}-FeSe single crystals. The {mu}{sub 0}H{sub c2}(T) increases as the temperature is lowered for fields applied parallel and perpendicular to (101), the natural growth facet of the crystal. The {mu}{sub 0}H{sub c2}(T) for both field directions and the anisotropy at low temperature increase under pressure. Hole carriers are dominant at high magnetic fields. However, the contribution of electron-type carriers is significant at low fields and low temperature. Our results show that multiband effects dominate {mu}{sub 0}H{sub c2}(T) and electronic transport in the normal state.

  19. Capillary effects in guided crystallization of organic thin films

    Directory of Open Access Journals (Sweden)

    Alta Fang

    2015-03-01

    Full Text Available Recently, it has been demonstrated that solvent-vapor-induced crystallization of triethylsilylethynyl anthradithiophene (TES ADT thin films can be directed on millimeter length scales along arbitrary paths by controlling local crystal growth rates via pre-patterning the substrate. Here, we study the influence of capillary effects on crystallization along such channels. We first derive an analytical expression for the steady-state growth front velocity as a function of channel width and validate it with numerical simulations. Then, using data from TES ADT guided crystallization experiments, we extract a characteristic channel width, which provides the smallest feature size that can be obtained by this technique.

  20. Anisotropies in sputtered FeCoV films and FeCoV/Ti:N multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, D.; Vananti, A.; Terrier, C.; Boeni, P.; Schnyder, B.; Tixier, S.; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    SQUID and MOKE magnetometry as well as mechanical and X-ray stress analysis have been used in order to prove the magnetostrictive nature of the anisotropy in Fe{sub 0.50}Co{sub 0.48}V{sub 0.02} films and Fe{sub 0.50}Co{sub 0.48}V{sub 0.02} /Ti:N multilayers. The investigation stresses on the dependence on the sputter gas pressure and on the thickness of the deposited layer. (author) 1 fig., 6 refs.

  1. Thermoelectric properties of epitaxial β-FeSi2 thin films grown on Si(111) substrates with various film qualities

    Science.gov (United States)

    Watanabe, Kentaro; Taniguchi, Tatsuhiko; Sakane, Shunya; Aoki, Shunsuke; Suzuki, Takeyuki; Fujita, Takeshi; Nakamura, Yoshiaki

    2017-05-01

    Si-based epitaxial β-FeSi2 thin films are attractive as materials for on-chip thermoelectric power generators. We investigated the structure, crystallinity, and thermoelectric properties of β-FeSi2 thin films epitaxially grown on Si(111) substrates by using three different techniques: conventional reactive deposition epitaxy followed by molecular beam epitaxy (RDE+MBE), solid phase epitaxy (SPE) based on codeposition of Fe and Si presented previously, and SPE followed by MBE (SPE+MBE) presented newly by this work. Their epitaxial growth temperatures were fixed at 530 °C for comparison. RDE+MBE thin films exhibited high crystalline quality, but rough surfaces and rugged β-FeSi2/Si(111) interfaces. On the other hand, SPE thin films showed flat surfaces and abrupt β-FeSi2/Si(111) interfaces but low crystallinity. We found that SPE+MBE thin films realized crystallinity higher than SPE thin films, and also had flatter surfaces and sharper interfaces than RDE+MBE thin films. In SPE+MBE thin film growth, due to the initial SPE process with low temperature codeposition, thermal interdiffusion of Fe and Si was suppressed, resulting in the surface flatness and abrupt interface. Second high temperature MBE process improved the crystallinity. We also investigated thermoelectric properties of these β-FeSi2 thin films. Structural factors affecting the thermoelectric properties of RDE+MBE, SPE, and SPE+MBE thin films were investigated.

  2. Ferroelectric, ferromagnetic and optical properties of KBiFe2O5 thin film: a structure property relationship

    Science.gov (United States)

    Jalaja, M. A.; Predeep, P.; Dutta, Soma

    2017-01-01

    KBiFe2O5 thin film was prepared by spin-coating on platinized (111) Si wafer and characterized for its structure, microstructure, ferroelectric, magnetic and optical properties. X-ray diffraction (XRD) revealed a noncentrosymmetric, orthorhombic crystal structure of KBiFe2O5. The well-distributed dense microstructure with large grain and narrow grain boundaries in KBiFe2O5 enhanced its ferroelectric properties. The strong, frequency-dependent behavior of the ferroelectric hysteresis loop suggested the leaky nature of the material. Piezoelectricity was confirmed by determining the piezoelectric charge coefficients (d 33 = 2.82 nm V-1 at positive bias and 3.195 nm V-1 at negative bias voltage) from the field versus the displacement plot. The weak ferromagnetism of the film is attributed to the high spin state of Fe3+ in the FeO4 tetrahedron of KBiFe2O5. Optical properties (refractive indices and extinction coefficients) are studied from the reflectance spectrum. The refractive indices are higher in the visible region and showed a normal dispersion in the blue region. The bandgap of the film was calculated to be 1.61 eV.

  3. Single Crystal Alloy Film Infrared Detectors.

    Science.gov (United States)

    1981-10-01

    evaporation; this excess chalco - genide is necessary to produce p-type lead salt epitaxial films. The tube was placed on the base plate of the evaporator with...maintain films of icomposition close to that of the source material (i.e., PbS0 .5Se0.5 ). hi -.The present conclusion concerninq use of the auxiliary chalco

  4. A complex magnetic structure of ultrathin Fe films on Rh (001) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Takada, Masaki [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Lana Gastelois, Pedro [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Servico de Nanotecnologia, Centro de Desenvolvimento da Tecnologia Nuclear, 31270-901 BeloHorizonte, MG (Brazil); Przybylski, Marek, E-mail: mprzybyl@mpi-halle.de [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow (Poland); Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Naturwissenschaftliche Fakultaet II, Martin-Luther-Universitaet Halle-Wittenberg, 06120 Halle (Germany)

    2013-03-15

    We conducted a structural and magnetic analysis of ultrathin Fe films on Rh (001) surfaces by using low electron energy diffraction (LEED), magneto-optical Kerr effects (MOKE) and spin-polarized scanning tunneling microscopy (SP-STM). The films in the investigated thickness range up to 6 monolayers (ML) are pseudomorphic to the Rh (001) substrate. While Fe films thinner than 3 ML grow layer-by-layer at room temperature (RT), Fe films thicker than 4 ML form islands. 1 ML Fe films do not show any hysteresis loops even at low temperature. Polar hysteresis loops for the 2 ML and 3 ML thick films appear at low temperatures. When 1 ML thick Fe films were studied by Cr- and Fe-coated W tips, a (2 Multiplication-Sign 3) and stripe structures were observed, respectively. The structures originate from a complex magnetic structure of 1 ML Fe. Based on the SP-STM results we propose a spin configuration model of a 1 ML Fe film. - Highlights: Black-Right-Pointing-Pointer We studied structural and magnetic properties of Fe films grown on an Rh (001). Black-Right-Pointing-Pointer MOKE measurements revealed that Fe films thicker than 2 ML are ferromagnetic at 5 K. Black-Right-Pointing-Pointer Fe films with thickness of 2 ML and 3 ML exhibit out-of-plane magnetization, those thicker than 4 ML show in-plane magnetization. Black-Right-Pointing-Pointer 1 ML Fe films have a complex magnetic configuration with zero net magnetization. Black-Right-Pointing-Pointer A spin configuration model of 1 ML Fe is proposed based on an SP-STM observation.

  5. Exceptionally high magnetization of stoichiometric Y3Fe5O12 epitaxial films grown on Gd3Ga5O12

    Science.gov (United States)

    Gallagher, James C.; Yang, Angela S.; Brangham, Jack T.; Esser, Bryan D.; White, Shane P.; Page, Michael R.; Meng, Keng-Yuan; Yu, Sisheng; Adur, Rohan; Ruane, William; Dunsiger, Sarah R.; McComb, David W.; Yang, Fengyuan; Hammel, P. Chris

    2016-08-01

    The saturation magnetization of Y3Fe5O12 (YIG) epitaxial films 4 to 250 nm in thickness has been determined by complementary measurements including the angular and frequency dependencies of the ferromagnetic resonance fields as well as magnetometry measurements. The YIG films exhibit state-of-the-art crystalline quality, proper stoichiometry, and pure Fe3+ valence state. The values of YIG magnetization obtained from all the techniques significantly exceed previously reported values for single crystal YIG and the theoretical maximum. This enhancement of magnetization, not attributable to off-stoichiometry or other defects in YIG, opens opportunities for tuning magnetic properties in epitaxial films of magnetic insulators.

  6. Giant Magneto-Impedance Effect in Sandwiched FeSiB/Cu/FeSiB Films

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yong; YANG Chun-Sheng; YU Jin-Qiang; ZHAO Xiao-Lin; MAO Hai-Ping

    2000-01-01

    Giant magneto-impedance (GMI) effect has been realized in the sandwiched FeSiB/Cu/FeSiB films. With magnetic field Ha and ac current applied along the longitudinal direction of the sample, the GMI ratio increases with the increasing Ha, reaching a positive maximum, value, and then decreases to negative values with further increase of magnetic field. Field dependence of the GMI ratio also indicates that the magnetic field corresponding to the maximum GMI ratio is different for various frequencies. The positive maximum GMI ratio is 17.2% for Ha=1600 A/m and frequency of 3 MHz. In addition, the films display a large negative GMI ratio with a magnetic field applied along the transverse direction and the value of the GMI ratio is about -13.4% for Ha=5600A/m and frequency of 3 MHz.

  7. Improved gas sensing and dielectric properties of Fe doped hydroxyapatite thick films: Effect of molar concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Mene, Ravindra U. [PDEA' s, Annasaheb Waghire College of Science, Arts and Commerce, Otur 412409, M.S. (India); School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India); Mahabole, Megha P. [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India); Mohite, K.C. [Haribhai. V. Desai College, Pune 411002, M.S. (India); Khairnar, Rajendra S., E-mail: rskhairnarsps@gmail.com [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India)

    2014-02-01

    Highlights: • We report improved gas sensing and dielectric characteristics of Fe ion exchanged HAp films. • Fe doped HAp film shows maximum gas response at relatively lower temperature. • Response and gas uptake capacity of sensors is improved for appropriate amount of Fe ions in HAp matrix. • Fe-HAp films exhibit remarkable improvement in dielectric properties compared to pure HAp. • Fe doped HAp films show significant improvement in gas sensing as well as in dielectric properties. - Abstract: In the present work Fe doped hydroxyapatite (Fe-HAp) thick films has been successfully utilized to improve the gas sensing as well as its dielectric properties. Initially, HAp nano powder is synthesized by chemical precipitation process and later on Fe ions are doped in HAp by ion exchange process. Structural and morphological modifications are observed by means of X-ray diffraction and scanning electron microscopy analysis. The sensing parameters such as operating temperature, response/recovery time and gas uptake capacity are experimentally determined. The Fe-HAp (0.05 M) film shows improved CO and CO{sub 2} gas sensing capacity at lower operating temperature compared to pure HAp. Moreover, variation of dielectric constant and dielectric loss for pure and Fe-HAp thick films are studied as a function of frequency in the range of 10 Hz–1 MHz. The study reveals that Fe doped HAp thick films improve the sensing and dielectric characteristics as compared to pure HAp.

  8. 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

  9. Researches on the Growth Habit and Optical Properties of Fe3+ Ion Doped KDP Crystal

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    During the process of KDP crystal growth, metal ions strongly affect the growth habit and optical properties of KDP single crystal. In this paper, KDP crystals were grown from an aqueous solution doped with different concentration of Fe3+ dopant by traditional temperaturereduction method and "point-seed" rapid growth method. Furthermore, we examined the light scatter and measured the transmission of these KDP crystals. It is found that the dopant of Fe3+ ion can improve the stability of the KDP growth solution when its concentration is less than 30 ppm.The effects of Fe3+ ion on the growth habit and optical properties of KDP crystal are also obvious.

  10. 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.

  11. Synergetic crystallization in a Nd2Fe14B/α-Fe nanocomposite under electron beam exposure conditions.

    Science.gov (United States)

    Tian, Haidong; Zhang, Yinfeng; Han, Jingzhi; Xu, Zhuang; Zhang, Xiaodong; Liu, Shunquan; Wang, Changsheng; Yang, Yingchang; Han, Li; Yang, Jinbo

    2016-10-27

    Nd2Fe14B/α-Fe nanocomposite magnets are prepared through electron beam exposure with a greatly reduced annealing time of 0.1 s. This is by far the most effective approach due to the effect of an extremely high heating rate featuring a rapid thermal process. The impact that the rapid thermal process has on crystallization is expounded by the introduction of the Landau model and Langevin dynamical simulations. The change of crystallization sequence from the α-Fe phase preceding the Nd2Fe14B phase under conventional annealing conditions, to synergetic crystallization under electron beam conditions is investigated. Synergetic crystallization results in more intense interaction between the α-Fe phase and the Nd2Fe14B phase in order to refine the microstructure as the fraction of Fe increases within our addition range. Improved uniformity, and shifts in the microstructure and distribution of the α-Fe phase contribute to the improvement of the magnetic properties. Compared with conventional furnace annealing ones, the magnetic properties of samples under electron beam exposure conditions are improved. For the Nd10Fe83.3B6.2Nb0.2Ga0.3 alloy, coercivity is enhanced from 4.56 kOe to 6.73 kOe, remanence ratio increases from 0.75 to 0.79, and a superior squareness of the hysteresis loop is achieved.

  12. Oxygen vacancy induced magnetization switching in Fe{sub 3}O{sub 4} epitaxial ultrathin films on GaAs(100)

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhaocong, E-mail: zhaocong.huang@gmail.com [Department of Physics, Southeast University, Nanjing 211189 (China); Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China); Chen, Qian; Zhai, Ya, E-mail: yazhai@seu.edu.cn, E-mail: jlwang@seu.edu.cn; Wang, Jinlan, E-mail: yazhai@seu.edu.cn, E-mail: jlwang@seu.edu.cn [Department of Physics, Southeast University, Nanjing 211189 (China); Xu, Yongbing [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); Wang, Baoping [School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China)

    2015-05-04

    The magnetic and transport properties of half metallic Fe{sub 3}O{sub 4}, which are sensitive to the stoichiometry, are the key issue for applications in spintronics. An anomalous enlargement of the saturation magnetic moment is found in a relatively thick sample of epitaxial Fe{sub 3}O{sub 4} film by post-growth oxidation method. The investigation of the thickness dependence of magnetic moment suggests that the enhanced magnetism moment may come from the existence of oxygen vacancies. First-principles calculations reveal that with oxygen vacancies in Fe{sub 3}O{sub 4} crystal the spin of Fe ions in the tetrahedron site near the vacancy is much easier to switch parallel to the Fe ions in the octahedron site by temperature disturbance, supported by the temperature dependence of magnetic moment of Fe{sub 3}O{sub 4} films in experiment.

  13. Unusual magnetotransport properties in a FeAs single crystal

    Science.gov (United States)

    Khim, Seunghyun; Gillig, Matthias; Klingeler, Rüdiger; Wurmehl, Sabine; Büchner, Bernd; Hess, Christian

    2016-05-01

    We have investigated the magnetoresistance (MR) and Hall resistivity properties of a FeAs single crystal which exhibits magnetic order below TN = 69 K. We observe nonlinear Hall resistivity and linear MR in the presence of magnetic-order-connected Fermi surface reconstruction. The analysis of the magnetotransport data using a two-carrier model suggests the emergence of an additional minor hole Fermi surface which coexists with major electron carriers below TN. The origin of the linear MR, however, remains inconsistent with current explanations based on the electronic band structure, i.e., the quantum linear MR model from linearly dispersive Dirac cones and linear MR as a result from strong velocity changes of the cyclotron motion near nested Fermi surfaces. While a macroscopic inhomogeneity in a mobility distribution may cause the linear MR as widely observed in other semimetals with high mobilities, the spiral magnetic order of FeAs seems to ask for an alternative description which takes the specific magnetic order and details of the electronic structure of FeAs as well as a possible entanglement between them into account.

  14. Location control of crystal grains in excimer laser crystallization of silicon thin films

    Science.gov (United States)

    Kumomi, Hideya

    2003-07-01

    Location of crystal grains in polycrystalline Si thin films formed by excimer-laser crystallization is controlled by manipulating the superlateral-growth phenomenon. The superlateral growth of a single grain occurs preferentially at an artificial site where nanometer-sized crystallites are embedded in the precursory amorphous thin films. Only a part of the crystallites embedded in the site could survive the melting and grow to serve as the seed crystal in the subsequent recrystallization. Such grain-location control provides a basis for two-dimensional control of the grain-boundary location in low-temperature polycrystalline Si thin films, which is essential to the device-to-device uniformity of high-performance thin-film transistors.

  15. Applications of thin-film sandwich crystallization platforms

    Energy Technology Data Exchange (ETDEWEB)

    Axford, Danny, E-mail: danny.axford@diamond.ac.uk; Aller, Pierre; Sanchez-Weatherby, Juan; Sandy, James [Diamond Light Source, Harwell Oxford, Didcot OX11 0DE (United Kingdom)

    2016-03-24

    Crystallization via sandwiches of thin polymer films is presented and discussed. Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal sample intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.

  16. Transport and magnetic properties of Fe3Si epitaxial films

    Science.gov (United States)

    Vinzelberg, H.; Schumann, J.; Elefant, D.; Arushanov, E.; Schmidt, O. G.

    2008-11-01

    The paper presents resistivity and magnetization measurements on nearly stoichiometric Fe3Si films epitaxially grown on GaAs substrates by electron-beam evaporation in an ultrahigh vacuum chamber. In the low-temperature resistivity a T3 term was found in all samples. A term like that is known to describe the anomalous single-magnon scattering processes in half-metallic materials and confirms so for our samples the hypothesis of half-metallic ferromagnetism in Fe3Si. The films show an anisotropic magnetoresistance in low magnetic fields. In high magnetic fields a negative longitudinal and transverse magnetoresistance (MR) has been observed linearly depending on the field strength. In the vicinity of 200 K the MR shows maximum absolute values up to 1.5% at magnetic fields of about 8 T. From the magnetization measurements a magnetic moment of 0.86μB/atom was obtained, which is close to that of bulk Fe3Si.

  17. Vibrational spectroscopy and analytical electron microscopy studies of Fe-V-O and In-V-O thin films

    CERN Document Server

    Vuk, A S; Drazic, G; Colomban, P

    2002-01-01

    Orthovanadate (M sup 3 sup + VO sub 4; M= Fe, In) and vanadate (Fe sub 2 V sub 4 O sub 1 sub 3) thin films were prepared using sol-gel synthesis and dip coating deposition. Using analytical electron microscopy (AEM), the chemical composition and the degree of crystallization of the phases present in the thin Fe-V-O films were investigated. TEM samples were prepared in both orientations: parallel (plan view) and perpendicular (cross section) to the substrate. In the first stages of crystallization, when the particle sizes were in the nanometer range, the classical identification of phases using electron diffraction was not possible. Instead of measuring d values, experimentally selected area electron diffraction (SAED) patterns were compared to calculated (simulated) patterns in order to determine the phase composition. The problems of evaluating the ratio of amorphous and crystalline phases in thin films are reported. Results of TEM and XRD as well as IR and Raman spectroscopy showed that the films made at lo...

  18. Twin nucleation and migration in FeCr single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Patriarca, L. [Politecnico di Milano, Department of Mechanical Engineering, Via La Masa 34, I-20156 Milano (Italy); Abuzaid, Wael [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801 (United States); Sehitoglu, Huseyin, E-mail: huseyin@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801 (United States); Maier, Hans J. [Lehrstuhl fuer Werkstoffkunde (Materials Science), University of Paderborn, 33095 Paderborn (Germany); Chumlyakov, Y. [Physics of Plasticity and Strength of Materials Laboratory, Siberian Physical and Technical Institute, 634050 Tomsk (Russian Federation)

    2013-01-15

    Tension and compression experiments were conducted on body-centered cubic Fe -47.8 at pct. Cr single crystals. The critical resolved shear stress (CRSS) magnitudes for slip nucleation, twin nucleation and twin migration were established. We show that the nucleation of slip occurs at a CRSS of about 88 MPa, while twinning nucleates at a CRSS of about 191 MPa with an associated load drop. Following twin nucleation, twin migration proceeds at a CRSS that is lower than the initiation stress ( Almost-Equal-To 114-153 MPa). The experimental results of the nucleation stresses indicate that the Schmid law holds to a first approximation for the slip and twin nucleation cases, but to a lesser extent for twin migration particularly when considerable slip strains preceded twinning. The CRSSs were determined experimentally using digital image correlation (DIC) in conjunction with electron back scattering diffraction (EBSD). The DIC measurements enabled pinpointing the precise stress on the stress-strain curves where twins or slip were activated. The crystal orientations were obtained using EBSD and used to determine the activated twin and slip systems through trace analysis. - Highlights: Black-Right-Pointing-Pointer Digital image correlation allows to capture slip/twin initiation for bcc FeCr. Black-Right-Pointing-Pointer Crystal orientations from EBSD allow slip/twin system indexing. Black-Right-Pointing-Pointer Nucleation of slip always precedes twinning. Black-Right-Pointing-Pointer Twin growth is sustained with a lower stress than required for nucleation. Black-Right-Pointing-Pointer Twin-slip interactions provide high hardening at the onset of plasticity.

  19. Magnetoelectric effect in FeCo/PMN-PT/FeCo trilayers prepared by electroless deposition of FeCo on PMN-PT crystals with various orientations

    Energy Technology Data Exchange (ETDEWEB)

    Shen, H.Q.; Wang, Y.G., E-mail: yingang.wang@nuaa.edu.cn; Xie, D.; Cheng, J.H.

    2014-10-15

    Highlights: • The composites FeCo/PMN-PT/FeCo were prepared by electroless deposition. • The influence of the crystal cut of PMN-PT on ME coupling is discussed. • Optimizing the crystal cut of the piezoelectric substrate, proper resonant frequency and ME effect could be obtained. - Abstract: The magnetoelectric (ME) effect was studied in the FeCo/PMN-PT/FeCo trilayer composites prepared by electroless deposition of the FeCo layers on the single crystal PMN-PT substrates with various crystal cuts. X-ray diffraction reveals that the orientation of PMN-PT substrate has no effect on the growth of FeCo layer. The structures with PMN-PT crystals of various orientations have different acoustic resonance frequencies. FeCo/PMN-PT/FeCo composites with PMN-PT of 〈0 0 1〉{sup L} × 〈01{sup ‾}1〉{sup W} × 〈0 1 1〉{sup T} crystal cut shows superior ME performance, which is due to the highest piezoelectric module of PMN-PT.

  20. In-plane anisotropic converse magnetoelectric coupling effect in FeGa/polyvinylidene fluoride heterostructure films

    Science.gov (United States)

    Zuo, Zhenghu; Zhan, Qingfeng; Dai, Guohong; Chen, Bin; Zhang, Xiaoshan; Yang, Huali; Liu, Yiwei; Li, Run-Wei

    2013-05-01

    We investigated the converse magnetoelectric (CME) effect in the Fe81Ga19/polyvinylidene fluoride (PVDF) heterostructure films. A weak in-plane uniaxial magnetic anisotropy was observed in the as-deposited magnetostrictive FeGa films. When a positive (negative) electric field is applied on the ferroelectric PVDF substrates, both the coercivity and the squareness of magnetic hysteresis loops of FeGa films for the magnetic field parallel to the easy axis become larger (smaller), but for the magnetic field parallel to the hard axis the coercivity and the remanence get smaller (larger), indicating an anisotropic CME effect in FeGa/PVDF heterostructure films.

  1. Optical Property of LiNbO3 Crystal Codoped with In, Mg and Fe

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In2O3, MgO and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO3 crystals. The OH- extension transmission spectra, light scattering resistance ability, two wave coupled diffraction efficiency and response time of the crystal were measured. Codoping In and Mg in crystal will improve its light scattering resistance ability and response time. Doping In can increase the ability to replace antisite Nb and decrease the doping quantity of Mg. All these are propitious to improve the optical homogeneity of crystal. Doping Fe can improve the photorefractive sensitivity for LiNbO3 crystal. We discussed the site of In, Mg and Fe in LiNbO3 crystals and the influence of the absorption peak of OH- transmission spectra on photorefractive property for LiNbO3 crystal.

  2. Selective-resputtering-induced perpendicular magnetic anisotropy in amorphous TbFe films.

    Science.gov (United States)

    Harris, V G; Pokhil, T

    2001-08-06

    Perpendicular magnetic anisotropy energy in rf magnetron sputtered amorphous TbFe films is measured to increase exponentially with pair-order anisotropy induced by the selective resputtering of surface adatoms during film growth.

  3. Tb-Dy-Fe Single Crystal and Magnetostrictive Actuator Using These Materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Magnetostrictive actuators normally use twin-crystal magnetostrictive materials as driving unit. Because the crystal and twin-crystal plane hinder the movement of the domain wall, its displacement output of low magnetic strength is rather small. Using Tb-Dy-Fe single crystal technique can effectively solve the problems brought by pollution and twin crystals, and produce high-quality Tb-Dy-Fe single crystal materials. The paper will introduce the technique of using these materials to produce magnetostrictive actuators that possess high sensitivity and resolution and use pulse feeding.

  4. Soft Magnetic Thin Films FeCoHfO for High-Frequency Noise Suppression Applications

    Institute of Scientific and Technical Information of China (English)

    LU Guang-Duo; ZHANG Huai-Wu; TANG Xiao-Li

    2010-01-01

    @@ A series of FeCoHfO films were fabricated by dc magnetron reactive sputtering at varying partial pressure of oxygen(Po2)from 0 to 11.7%,and the electrical and magnetic properties of films have been studied.It is shown that optimal Fe43.29 Co19.51 Hf7.49O29.71 films with desired properties can be obtained when the films were prepared under Po2 = 5.1%.

  5. Heat Flux Through Slag Film and Its Crystallization Behavior

    Institute of Scientific and Technical Information of China (English)

    TANG Ping; XU Chu-shao; WEN Guang-hua; ZHAO Yan-hong; QI Xin

    2008-01-01

    An experimental apparatus for simulating copper mold is used to quantify the heat flux through the slag film and to obtain a solid slag for further determining its crystallization behavior.The result indicates that both the chemical composition of the mold powder and the cooling rate have an important influence on the heat flux through the slag film.With increasing the binary hasicity,the heat flux of slag film decreases at first,reaches the minimum at the basicity of 1.4,and then increases,indicating that the maximum binary basicity is about 1.4 for selecting"mild cooling"mold powder.The heat transfer through the slag film can be specified in terms of the crystalline ratio and the thickness of the slag film.Reerystallization of the solid slag occurs and must be considered as an important factor that may influence the heat transfer through the solid slag layer.

  6. Faraday Effect sensor redressed by Nd2Fe14B biasing magnetic film.

    Science.gov (United States)

    Jiao, Xinbing; Nguyen, Truong Giang; Qian, Bo; Jiang, Chunping; Ma, Lixin

    2012-01-16

    A Faraday Effect sensor with Nd(2)Fe(14)B biasing magnetic film was described. Ta/Nd(2)Fe(14)B/Ta films were grown by magnetron sputtering method. The magnetic domain in the sensor with the Nd(2)Fe(14)B biasing magnetic film can persist its distribution. The average linearity error of Faraday Effect sensor with biasing magnetic film decreased from 1.42% to 0.125% compared with non-biasing magnetic film, and the measurement range increased from 820 Oe to 900 Oe.

  7. Protection of NdFeB magnets by corrosion resistance phytic acid conversion film

    Science.gov (United States)

    Nan, Haiyang; Zhu, Liqun; Liu, Huicong; Li, Weiping

    2015-11-01

    Phytic acid conversion film was prepared on NdFeB magnets by dipping the NdFeB into phytic acid solution. The morphology, composition, structure and corrosion resistance of the film were systematically investigated. The results showed that the phytic acid film was effective in improving the corrosion resistance of NdFeB magnets. XRD, TEM and FT-IR analyses revealed that the film was amorphous and had a strong peak of phosphate radical (PO43-). The formation mechanism of the film was also explored by XPS and the potential of zero charge (Epzc) measurement at the solution-metal interface.

  8. Epitaxial Fe3Si films on GaAs(100) substrates by means of electron beam evaporation

    Science.gov (United States)

    Thomas, J.; Schumann, J.; Vinzelberg, H.; Arushanov, E.; Engelhard, R.; Schmidt, O. G.; Gemming, T.

    2009-06-01

    This paper presents results on the preparation, structural, electrical and magnetic properties of Fe3Si films as a representative for a Heusler alloy-like compound which are known as half-metallic materials with ferromagnetic behaviour. The films have been prepared by means of ultra-high vacuum (UHV) electron beam evaporation with the aim of achieving epitaxial growth on GaAs(100) substrates. The main focus of this work is the structural characterization of the Fe3Si films grown on GaAs by means of high resolution transmission electron microscopy (TEM) to confirm the epitaxial growth. For Fe3Si with a composition in the vicinity of stoichiometry an almost lattice-matched growth on GaAs(001) has been observed characterized by a high crystalline quality and a good interface perfection. Besides the studies on cross-sectional samples by TEM data from reflection high energy electron diffraction (RHEED) and x-ray diffraction (XRD) were also included into the discussion. The electrical and magnetic parameters of the films studied are found to be in good agreement with data reported for the best Fe3Si molecular beam epitaxy (MBE) layers. As evidenced by x-ray diffraction, transmission electron microscopy, resistivity and magnetic measurements, we find an optimum growth temperature of 280-350 °C to obtain ferromagnetic layers with high crystal and interface perfection as well as a high degree of atomic ordering.

  9. Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

    Energy Technology Data Exchange (ETDEWEB)

    Higashi, T.; Ohmori, M.; Ramananarivo, M. F.; Fujii, A., E-mail: afujii@opal.eei.eng.osaka-u.ac.jp; Ozaki, M. [Division of Electrical, Electronic, and Information Engineering, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

    2015-12-01

    The effects of solvent vapor on spin-coated films of a polymorphic phthalocyanine derivative were investigated. Growth of single crystal films via redissolving organic films under solvent vapor was revealed by in situ microscopic observations of the films. X-ray diffraction measurement of the films after exposing to solvent vapor revealed the phase transition of polymorphs under solvent vapor. The direction of crystal growth was clarified by measuring the crystal orientation in a grown monodomain film. The mechanism of crystal growth based on redissolving organic films under solvent vapor was discussed in terms of the different solubilities of the polymorphs.

  10. Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

    Directory of Open Access Journals (Sweden)

    T. Higashi

    2015-12-01

    Full Text Available The effects of solvent vapor on spin-coated films of a polymorphic phthalocyanine derivative were investigated. Growth of single crystal films via redissolving organic films under solvent vapor was revealed by in situ microscopic observations of the films. X-ray diffraction measurement of the films after exposing to solvent vapor revealed the phase transition of polymorphs under solvent vapor. The direction of crystal growth was clarified by measuring the crystal orientation in a grown monodomain film. The mechanism of crystal growth based on redissolving organic films under solvent vapor was discussed in terms of the different solubilities of the polymorphs.

  11. Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

    Directory of Open Access Journals (Sweden)

    Hao-Min Xu

    2016-11-01

    Full Text Available Pure BiFeO3 and heterostructured BiFeO3/BiFe0.95Mn0.05O3 (5% Mn-doped BiFeO3 thin films have been prepared by a chemical deposition method. The band structures and photosensitive properties of these films have been investigated elaborately. Pure BiFeO3 films showed stable and strong response to photo illumination (open circuit potential kept −0.18 V, short circuit photocurrent density was −0.023 mA·cm−2. By Mn doping, the energy band positions shifted, resulting in a smaller band gap of BiFe0.95Mn0.05O3 layer and an internal field being built in the BiFeO3/BiFe0.95Mn0.05O3 interface. BiFeO3/BiFe0.95Mn0.05O3 and BiFe0.95Mn0.05O3 thin films demonstrated poor photo activity compared with pure BiFeO3 films, which can be explained by the fact that Mn doping brought in a large amount of defects in the BiFe0.95Mn0.05O3 layers, causing higher carrier combination and correspondingly suppressing the photo response, and this negative influence was more considerable than the positive effects provided by the band modulation.

  12. A TEM study on the crystallization of amorphous Fe 73Si 3B 24 alloys

    Science.gov (United States)

    Lijun, Wu; Lihua, Zhao; Wangyu, Hu; Lingling, Wang; Juemin, Xiao

    1994-02-01

    The crystallization of Fe 73Si 3B 24 amorphous alloys has been studied by transmission electron microscopy (TEM). A metastable phase P has been found and determined by a double tilting method in TEM. This phase belongs to a primitive tetragonal lattice with a = 0.62 nm and c = 1.43 nm. Its probable space group is P4nc or P4/mnc. In the Fe 2B phase, we found threefold twins which are rotated 120° around the [ overline1 1 0] axis. The crystallization process of this alloy is suggested to be Amorphous→Amorphous + α-Fe(Si) + Fe 3B + P → α-Fe(Si) + Fe 3B + Fe 2B → α-Fe(Si) + Fe 2B.

  13. Thin film process forms effective electrical contacts on semiconductor crystals

    Science.gov (United States)

    Formigoni, N. P.; Roberts, J. S.

    1967-01-01

    Process makes microscopic, low-resistance electrical contacts on hexagonal n-type silicon carbide crystals used for microelectronic devices. A vacuum deposition of aluminum is etched to expose the bare silicon carbide where the electrical contacts are made. Sputtering alternating layers of tantalum and gold forms the alloy film.

  14. Observation of second spin reorientation transition within ultrathin region in Fe films on Ag(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Khim, T.-Y. [c-CCMR and Department of Physics, POSTECH, Pohang 790-784 (Korea, Republic of); Shin, M.; Lee, H., E-mail: easyscan@sookmyung.ac.kr, E-mail: jhp@postech.ac.kr [Department of Chemistry, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of); Park, B.-G. [Pohang Accelerator Laboratory (PAL), Pohang 790-784 (Korea, Republic of); Park, J.-H., E-mail: easyscan@sookmyung.ac.kr, E-mail: jhp@postech.ac.kr [c-CCMR and Department of Physics, POSTECH, Pohang 790-784 (Korea, Republic of); Division of Advanced Materials Science, POSTECH, Pohang 790-784 (Korea, Republic of); Max Plank POSTECH Center for Complex Phase Materials, POSTECH, Pohang 790-784 (Korea, Republic of)

    2014-06-21

    We acquired direct measurements for in-plane and perpendicular-to-plane magnetic moments of Fe films using an x-ray magnetic circular dichroism technique with increase of the Fe thickness (up to 40 Å) on the Ag(001) surface. Epitaxial Fe/Ag(001) films were grown in situ with the thickness varying from 2 Å to 40 Å, and the magnetic anisotropy was carefully investigated as a function of the film thickness. We found re-entrance of the in-plane magnetic anisotropy of the Fe film in ultrathin region. The results manifest that the epitaxial Fe/Ag(001) film undergoes two distinct spin reorientation transitions from in-plane to out-of-plane at the film thickness t ≈ 9 Å and back to in-plane at t ≈ 18 Å as t increases.

  15. 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.

  16. Growth and magnetic properties of ultrathin epitaxial FeO films and Fe/FeO bilayers on MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Kozioł-Rachwał, A., E-mail: akoziol@agh.edu.pl [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Ślęzak, T. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Nozaki, T.; Yuasa, S. [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Korecki, J. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland)

    2016-01-25

    Ultrathin FeO(001) films were grown via molecular beam epitaxy on MgO(001) using reactive deposition of Fe. The growth conditions were adjusted toward stabilization of the wüstite phase, the existence of which was confirmed by means of conversion electron Mössbauer spectroscopy. It was shown how the metallic Fe overlayer modified the chemical state and the magnetic properties of the FeO oxide. Finally, we observed the exchange bias for an epitaxial Fe/FeO bilayer grown on MgO(001)

  17. 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.

  18. Structure, magnetism, and interface properties of epitactical thin Fe and FePt films on GaAs(001) substrates; Struktur, Magnetismus und Grenzflaecheneigenschaften epitaktischer duenner Fe- und FePt-Filme auf GaAs(001)-Substraten

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Ellen Ursula

    2007-12-17

    The research in this thesis is focused on the study of the Fe spin structure and interface magnetism of thin epitaxial Fe layers or epitaxial FePt alloy films with chemical L1{sub 0} order on GaAs(001) surfaces. The main method of investigation was isotope-specific conversion electron Moessbauer spectroscopy (CEMS) combined with the {sup 57}Fe probe-layer technique in the temperature range of 4.2-300 K. The film structure was studied using electron diffraction (RHEED) and X-ray diffraction (XRD). The chemical order parameter S determined by XRD was found to increase with rising growth temperature, T{sub S}, to a maximum value of 0.71, until long range order is destroyed at T{sub S}>350 C by alloying with the substrate. As an important result a linear correlation between short-range order (revealed by the relative spectral area of the L1{sub 0} phase) and long-range order S was observed. The observed perpendicular Fe spin texture, characterized by the mean tilting angle left angle {theta} right angle of the Fe spins (relative to the film normal direction), was found to correlate with the L1{sub 0} phase content and with S. Furthermore, epitaxial Fe(001) films on GaAs(001)-(4 x 6) and on GaAs(001)-LED surfaces were grown successfully. In the initial stage of Fe film growth non-monotonous behavior of the in-plane lattice parameter was observed by RHEED. The magnetic hyperfine field distributions P(B{sub hf}) at the Fe/GaAs interface extracted from CEMS spectra for T{sub S}=-140 C or room temperature (RT) were found to be very similar. The observed large mean hyperfine fields of left angle B{sub hf} right angle {approx}25-27 T at the interface indicate the presence of high average Fe moments of 1.7-1.8 {mu}{sub B}. Nonmagnetic interface layers either can be excluded (Fe/GaAs) or are very thin (0.5 ML,Fe/GaAs-LED). Owing to its island structure an ultrathin (1.9 ML thick) uncoated Fe(001) film on GaAs(001)-(4 x 6) shows superparamagnetism with a blocking temperature of

  19. Effects of milling and crystallization conditions on microstructure of Nd2Fe14B/α-Fe powder

    Institute of Scientific and Technical Information of China (English)

    WANG Ying; WANG Er-de

    2007-01-01

    Effects of milling and crystallization conditions on microstructure, such as amorphous phase and nanocrystalline phase, were investigated by X-ray diffractometry(XRD), differential scanning calorimetry(DSC), and transmission electron microscopy (TEM), respectively. The results show that nanocomposite Nd2Fe14B/α-Fe powder can be prepared by mechanical milling in argon atmosphere and a subsequent vacuum annealing treatment. The grain sizes of both Nd2Fe14B and α-Fe phase decrease drastically with increasing milling time. After milling for 5 h, the as-milled material consists of α-Fe nanocomposite phases with the grain size of 10 nm, and some amorphous phases, which can be turned into Nd2Fe14B/α-Fe nanocomposite phases by the subsequent annealing treatment. Milling energy of mechanical milling after 5 h by theoretical calculation is 6 154.25 kJ/g.

  20. Combined effects of Bi deficiency and Mn substitution on the structural transformation and functionality of BiFeO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingyi; Wang, Yao, E-mail: wang-yao@buaa.edu.cn; Deng, Yuan, E-mail: dengyuan@buaa.edu.cn [School of Materials Science and Engineering, Beijing Key Laboratory for Advance Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China)

    2014-11-07

    Mn-doped BiFeO{sub 3} films with Mn contents of 5 and 10 mol. % were prepared via a chemical route. A carefully controlled amount of Bi deficiency was introduced to further tune the lattice structure and the functionality of multiferroic BiFeO{sub 3}. The crystal structure of Bi{sub 1−δ}Fe{sub 1−x}Mn{sub x}O{sub 3} films was investigated by X-ray diffraction and Raman spectra; a rhombohedral-to-orthorhombic phase transition was revealed. The observed double hysteresis loops and two capacitance maxima from polarization vs electric field and capacitance-voltage measurements indicate an antiferroelectric-like behavior. Additionally, the coexistence of ferroelectric (FE) and antiferroelectric (AFE) phases in Bi{sub 1−δ}Fe{sub 1−x}Mn{sub x}O{sub 3} films was revealed from the domain structures obtained by piezoelectric force microscopy. The effects of Mn substitution in conjunction with Bi deficiency on the FE-AFE phase transition and electrical behavior of BiFeO{sub 3} films are discussed in detail. Meanwhile, magnetic and photoluminescence measurements on the films illustrate that Mn substitution gives rise to the net magnetic moment and the defects induced by both Bi deficiency and Mn substitution influence the electronic structure of BiFeO{sub 3} films. This study thus shows a simple and effective way to control the functionalities of BiFeO{sub 3} films.

  1. 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.

  2. High-induction nanocrystalline soft magnetic Fe{sub X}Ti{sub Y}B{sub Z} films prepared by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Sheftel, Elena N.; Tedzhetov, Valentin A.; Harin, Eugene V.; Usmanova, Galina Sh. [A.A. Baikov Institute of Metallurgy and Material Science, Russian Academy of Sciences, Moscow (Russian Federation); Kiryukhantsev-Korneev, Filipp V. [National University of Science and Technology ' ' MISIS' ' , Moscow (Russian Federation)

    2016-12-15

    To design films with the Fe/TiB{sub 2} nanocomposite structure, which are characterized by high saturation induction B{sub s}, the phase and structural states and static magnetic properties of Fe-TiB{sub 2} films prepared by magnetron sputtering and subjected to subsequent annealing have been studied. According to X-ray diffraction data, either amorphous or nanocrystalline single-phase structure (an α-Fe(Ti,B) supersaturated solid solution with a bcc crystal lattice) is formed in the as-sputtered films. Depending on the film composition, the grain size of the α-Fe(Ti,B) phase varies from 45.6 to 6.5 nm; grains are characterized by high microstrain (0.21-4.96%). The annealing at 200-500 C leads to a decrease in the lattice parameter of the α-Fe(Ti,B) phase, i.e. to its depletion of titanium and boron and to the formation of two-phase α-Fe + Fe{sub 3}B structure after annealing at 500 C. The annealing at 200-500 C almost does not affect the grain size and microstrain of the bcc α-Fe-based phase. The amorphous state of the films is stable up to 500 C. All studied films are ferromagnets; the saturation induction B{sub s}(0.95-2.13 T) and coercive field H{sub c} (0.4-5 kA/m) of the films were determined. Correlations between the B{sub s} and H{sub c} magnitudes and the chemical composition of the films, their phase and structural states and magnetic structure are discussed. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Fe3O4(001) films on Fe(001): Termination and reconstruction of iron-rich surfaces

    DEFF Research Database (Denmark)

    Spiridis, N.; Barbasz, J.; Lodziana, Zbigniew;

    2006-01-01

    High-quality and impurity-free magnetite surfaces with (root 2x root 2)R45 degrees reconstruction have been obtained for the Fe3O4(001) epitaxial films deposited on Fe(001). Based on atomically resolved scanning tunneling microscopy images for both negative and positive sample polarity and densit...

  4. Hot Plate Annealing at a Low Temperature of a Thin Ferroelectric P(VDF-TrFE Film with an Improved Crystalline Structure for Sensors and Actuators

    Directory of Open Access Journals (Sweden)

    Rahman Ismael Mahdi

    2014-10-01

    Full Text Available Ferroelectric poly(vinylidene fluoride-trifluoroethylene (P(VDF-TrFE copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE thin films are measured as a function of different annealing temperatures (80 to 140 °C. It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

  5. Hot plate annealing at a low temperature of a thin ferroelectric P(VDF-TrFE) film with an improved crystalline structure for sensors and actuators.

    Science.gov (United States)

    Mahdi, Rahman Ismael; Gan, W C; Abd Majid, W H

    2014-10-14

    Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE) thin films are measured as a function of different annealing temperatures (80 to 140 °C). It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc) has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE) thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

  6. Oxidative degradation of industrial wastewater using spray deposited TiO2/Au:Fe2O3 bilayered thin films.

    Science.gov (United States)

    Mahadik, M A; Shinde, S S; Pathan, H M; Rajpure, K Y; Bhosale, C H

    2014-12-01

    The Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films are successfully prepared by the spray pyrolysis technique at an optimised substrate temperature of 400 °C and 470 °C, respectively onto amorphous and F:SnO2 coated glass substrates. The effect of TiO2 layer onto photoelectrochemical (PEC), structural, optical and morphological properties of Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films is studied. The PEC characterization shows that, maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 185 μA and Voc = 450 mV) are at 38 nm thickness of TiO2. Deposited films are polycrystalline with a rhombohedral and anatase crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform with seed like grains. The photocatalytic activities of the large surface area (64 cm(2)) TiO2/Au:Fe2O3 thin film photocatalysts were evaluated by photoelectrocatalytic degradation of industrial wastewater under sunlight light irradiation. The results show that the TiO2/Au:Fe2O3 thin film photocatalyst exhibited about 87% and 94% degradation of pollutant in sugarcane and textile industrial wastewater, respectively. The significant reduction in COD and BOD values from 95 mg/L to 13 mg/L and 75 mg/L to 11 mg/L, respectively was also observed.

  7. Epitactical FeAl films on sapphire and their magnetic properties; Epitaktische FeAl-Filme auf Saphir und ihre magnetischen Eigenschaften

    Energy Technology Data Exchange (ETDEWEB)

    Trautvetter, Moritz

    2011-05-05

    In the presented thesis epitaxial FeAl thin films on sapphire have been prepared by pulse laser deposition (PLD). The thin films deposited at room temperature exhibits ferromagnetism and subsequent annealing is necessary to transform the thin films to paramagnetic B2-phase, where the transition temperature depends on the crystalline orientation of the sapphire substrate. Alternatively, by deposition at higher substrate temperature the B2-phase is obtained directly. However, morphology of the FeAl film is influenced by different growth modes resulting from different substrate temperatures. The paramagnetic FeAl films can then be transformed to ferromagnetic phase by successive ion irradiation. Independent of the ion species used for irradiation, the same universal relation between thin films' coercive fields and irradiation damage is identified. The ion irradiation ferromagnetism can be transformed back to paramagnetism by subsequent annealing. The mutual transition between ferromagnetic and paramagnetic phases has been performed several times and shows full reversibility. The ferromagnetic phase induced by Kr{sup +} irradiation exhibits structural relaxation, where the saturate magnetization of FeAl thin film gradually decreases in several days. Later, ion irradiation has been performed selectively on defined areas of the thin film with the help of an unconventional lithography technique. The subsequent thin film is composed of ordered hexagonal array of ferromagnetic nano-cylinders separated by a paramagnetic matrix, suggesting a promising system for magnetic data storage. (orig.)

  8. Crystallization of [Fe4S3]-ferredoxin from the hyperthermophile archaeon pyrococcus furiosus

    DEFF Research Database (Denmark)

    Nielsen, Michael Ericsson Skovbo; Harris, Pernille; Christensen, Hans Erik Mølager

    2003-01-01

    Recombinant Pyrococcus furiosus ferredoxin with a [Fe3S4]-cluster was crystallized through steps of optimization and X-ray diffraction data were collected from several crystal forms. Flat plate-like crystals were grown by hanging-drop vapour diffusion. The precipitant used was 30% PEG 400; the p...

  9. Tailoring the mechanical properties of steel sheets using FeC films and diffusion annealing

    Energy Technology Data Exchange (ETDEWEB)

    Cantergiani, Elisa [Department of Mechanical Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Fillon, Amélie [Université de Rouen, Groupe de Physique des Matériaux, UMR CNRS 6634, BP-12, 76801, Saint Etienne du Rouvray Cedex (France); Lawrence, Ben [The University of British Columbia, Dept. of Materials Engineering, 309-6350 Stores Road, Vancouver, Canada V6T1Z4 (Canada); Sauvage, Xavier [Université de Rouen, Groupe de Physique des Matériaux, UMR CNRS 6634, BP-12, 76801, Saint Etienne du Rouvray Cedex (France); Perez, Michel [Université de Lyon, MATEIS-INSA-Lyon, UMR CNRS 5510, 69621 Villeurbanne (France); Scott, Colin P. [Canmet MATERIALS, Hamilton, ON, Canada L8P0A5 (Canada); Weck, Arnaud, E-mail: aweck@uottawa.ca [Department of Mechanical Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Centre for Research in Photonics at the University of Ottawa, 800 King Edward Ave., Ottawa, ON, Canada K1N 6N5 (Canada)

    2016-03-07

    In this work amorphous FeC films were deposited on thin sheets of interstitial free steel using physical vapor deposition. Annealing treatments were then carried out to diffuse C from the coating into the substrate at temperatures lower than those traditionally used in carburizing treatments. The yield stress was shown to significantly increase with annealing temperature from ~120 MPa at 25 °C up to a maximum of 300 MPa at 630 °C without any significant loss of ductility. At 710 °C, a decrease in yield strength was related to the coarsening of carbides inside the IF steel (confirmed by atom probe tomography), and the associated reduction in the matrix solid solution carbon concentration (confirmed by thermoelectric power measurements). The through-thickness carbon diffusion profile was predicted using Fick's law and validated by Knoop hardness measurements. Yield strength predictions were accurate if the crystallization of the FeC film was taken into account as it controls the amount of carbon available to be diffused in the interstitial free steel substrate.

  10. Formation of β-FeSi 2 thin films by partially ionized vapor deposition

    Science.gov (United States)

    Harada, Noriyuki; Takai, Hiroshi

    2003-05-01

    The partially ionized vapor deposition (PIVD) is proposed as a new method to realize low temperature formation of β-FeSi 2 thin films. In this method, Fe is evaporated by E-gun and a few percents of Fe atoms are ionized. We have investigated influences of the ion content and the accelerating voltage of Fe ions on the structural properties of β-FeSi 2 films deposited on Si substrates. It was confirmed that β-FeSi 2 can be formed on Si(1 0 0) substrate by PIVD even at substrate temperature as low as 350, while FeSi by the conventional vacuum deposition. It was concluded that the influence of Fe ions on preferential orientation of β-FeSi 2 depends strongly on the content and the acceleration energy of ions.

  11. Effect of buffer layer and external stress on magnetic properties of flexible FeGa films

    Science.gov (United States)

    Zhang, Xiaoshan; Zhan, Qingfeng; Dai, Guohong; Liu, Yiwei; Zuo, Zhenghu; Yang, Huali; Chen, Bin; Li, Run-Wei

    2013-05-01

    We systematically investigated the effect of a Ta buffer layer and external stress on the magnetic properties of magnetostrictive Fe81Ga19 films deposited on flexible polyethylene terephthalate (PET) substrates. The Ta buffer layers could effectively smoothen the rough surface of PET. As a result, the FeGa films grown on Ta buffer layers exhibit a weaker uniaxial magnetic anisotropy and lower coercivity, as compared to those films directly grown on PET substrates. By inward and outward bending the FeGa/Ta/PET samples, external in-plane compressive and tensile stresses were applied to the magnetic films. Due to the inverse magnetostrictive effect of FeGa, both the coercivity and squareness of hysteresis loops for FeGa/Ta films could be well tuned under various strains.

  12. Thermal-vacancy-assisted phase transition in FePt thin films

    Science.gov (United States)

    Li, X. H.; Wang, F. Q.; Liu, B. T.; Guo, D. F.; Zhang, X. Y.

    2011-04-01

    Understanding the ordering transition from A1 to L10 structure in FePt thin films is of great significance for developing L10-FePt films as ultrahigh density magnetic recording media. Here, the L10-ordering transition of FePt films has been investigated based on activation volume measurements. A large activation volume ΔV ∗=10-11 Å3=(0.75-0.8) Ω, where Ω is average atomic volume of FePt, is determined for atomic diffusions in the L10-ordering transition, indicating a thermal-vacancy-assisted phase transition. This transition is suggested to be predominantly dependent on the diffusion of Fe atoms. These findings have direct implications for yielding L10-FePt films at low temperatures and optimizing their microstructures.

  13. Fabrication of FeSe superconducting films with chemical transport deposition process

    Science.gov (United States)

    Feng, J. Q.; Zhang, S. N.; Liu, J. X.; Hao, Q. B.; Li, C. S.; Zhang, P. X.

    2017-07-01

    FeSe Superconducting films were fabricated with a chemical transport deposition process. During the fabrication process, Fe foils were adopted as substrates and Se powders were put at one end of the tube furnace. During the heating process, Se powders were vaporized, and vaporized atoms were carried by Ar flow and deposited on the Fe substrates. With a heat treatment process under proper temperature, superconducting tetragonal β-FeSe phase can be obtained. The effects of key parameters, including the sintering temperatures and the distances between Fe substrates and Se source on the phase composition and morphology of the obtained films were systematically investigated. The superconducting transition temperature of 7.8 K was obtained on the optimized film. By further optimization of the heat treatment process, it is promising to fabricate FeSe films with higher superconducting phase content and better superconducting properties.

  14. Strain-Modulated Exchange-Spring Magnetic Behavior in Amorphous Tb-Fe Thin Films

    Science.gov (United States)

    Lee, Taehwan; Panduranga, Mohanchandra Kotekar; Han, Chang Wan; Ortalan, Volkan; Carman, Gregory Paul

    2017-08-01

    This paper studies the room-temperature exchange-spring magnetic behavior of amorphous TbFe films subjected to an applied strain. The cross-sectional composition measurement of the sputter-deposited TbFe film shows a compositional gradient through the thickness. The gradient is near the compensation composition of amorphous TbFe film producing a Tb-dominant region and a Fe-dominant region. The as-deposited film shows a two-step switching behavior with a negative coercive field, while an applied compressive (or tensile) strain eliminates (or enhances) the two-step switching behavior. The strain influence is attributed to the TbFe composition gradient and relatively large magnetoelastic property of the Tb-dominant region as compared to the Fe-dominant one.

  15. Temperature-Induced Magnetization Reorientation in GdFeCo/TbFeCo Exchange-Coupled Double Layer Films

    Institute of Scientific and Technical Information of China (English)

    王现英; 张约品; 李佐宜; 沈德芳; 干福熹

    2003-01-01

    GdFeCo/TbFeCo exchange-coupled double-layer (ECDL) films used for centre aperture type magnetically in duced super resolution were investigated through experiments and theoretical calculation. The ECDL films were prepared by the magnetron sputtering method. Polar Kerr effect measurements showed that magnetization reorientation occurred in the GdFeCo layer with the temperature rising, which was subsequently analysed by the micromagnetic calculation based on the mean-field theory and a continuum model. Theoretical analysis is in agreement well with the experimental results.

  16. Physical properties of hematite α-Fe2O3 thin films: application to photoelectrochemical solar cells

    Institute of Scientific and Technical Information of China (English)

    S. S. Shinde; R. A. Bansode; C. H. Bhosale; K. Y. Rajpure

    2011-01-01

    The physical properties and photoelectrochemical characterization of aluminium doped hematite α-Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron (Ⅲ) oxide thin films synthesized by a spray pyrolysis technique reveals an oxygen deficiency, and the oxide exhibits n-type conductivity confirmed by anodic photocurrent generation. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The deposited iron oxide thin films show the single hematite phase with polycrystalline rhombohedral crystal structure with crystallite size 20-40 nm. Optical analysis enabled to point out the increase in direct band-gap energy from 2.2 to 2.25 eV with doping concentration which is attributed to a blue shift. The dielectric constant and dielectric loss are studied as a function of frequency. To understand the conduction mechanism in the films, AC conductivity is measured. The conduction occurs by small polaron hopping through mixed valences Fe2+/3+ with an electron mobility 300 K of 1.08 cm2/(V.s). The α-Fe2O3 exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as a photoanode for various electrolytes using white light to obtain Ⅰ- characteristics. The Al-doped hematite exhibited a higher photocurrent response when compared with undoped films achieving a power conversion efficiency of 2.37% at 10 at% Al:Fe2O3 thin films along with fill factor 0.38 in NaOH electrolyte. The flat band potential Vfb (-0.87 VSCE) is determined by extrapolating the linear part to C-2 = 0 and the slope of the Mott-Schottky plot.

  17. Evaluation of Young's Modulus and Residual Stress of NiFe Film by Microbridge Testing

    Institute of Scientific and Technical Information of China (English)

    Zhimin ZHOU; Yong ZHOU; Mingjun WANG; Chunsheng YANG; Ji'an CHEN; Wen DING; Xiaoyu GAO; Taihua ZHANG

    2006-01-01

    Microbridge testing was used to measure the Young's modulus and residual stress of metallic films. Samples of freestanding NiFe film microbridge were fabricated by microelectromechanical systems. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curve of NiFe film microbridge by the Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of load-deflection curves of the microbridges was proposed to evaluate the Young's modulus and residual stress of the films simultaneously. The calculated results based on experimental measurements show that the average Young's modulus and residual stress for the electroplated NiFe films are 203.2 GPa and 333.0 MPa, respectively, while the Young's modulus measured by the Nano-hardness method is 209.6±11.8 GPa for the thick NiFe film with silicon substrate.

  18. Ion irradiation of Fe-Fe oxide core-shell nanocluster films. Effect of interface on stability of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    McCloy, John S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jiang, Weilin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Droubay, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Varga, Tamas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kovarik, Libor [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sundararajan, Jennifer A. [Univ. of Idaho, Moscow, ID (United States); Kaur, Maninder [Univ. of Idaho, Moscow, ID (United States); Qiang, You [Univ. of Idaho, Moscow, ID (United States); Burks, Edward [Univ. of California, Davis, CA (United States); Liu, Kai [Univ. of California, Davis, CA (United States)

    2013-08-23

    A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NC) of Fe core-Fe3O4 shell or fully oxidized Fe3O4. Films of these NC on Si(100) or MgO(100)/Fe3O4(100) were irradiated to 1016 Si2+/cm2 near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the nanocluster films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.

  19. Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor [Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, Washington 99352 (United States); Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You [Department of Physics, University of Idaho, Moscow, Idaho 83844 (United States); Burks, Edward C.; Liu, Kai [Department of Physics, University of California, Davis, California 95616 (United States)

    2013-08-28

    A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NCs) of Fe core-Fe{sub 3}O{sub 4} shell or fully oxidized Fe{sub 3}O{sub 4}. Films of these NC on Si(100) or MgO(100)/Fe{sub 3}O{sub 4}(100) were irradiated to 10{sup 16} Si{sup 2+}/cm{sup 2} near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the NC films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.

  20. Growth and characterizations of Ba2Ti2Fe2As4O single crystals

    Directory of Open Access Journals (Sweden)

    Yun-Lei Sun, Abduweli Ablimit, Jin-Ke Bao, Hao Jiang, Jie Zhou and Guang-Han Cao

    2013-01-01

    Full Text Available Single crystals of a new iron-based superconductor Ba2Ti2Fe2As4O have been grown successfully via a Ba2As3-flux method in a sealed evacuated quartz tube. Bulk superconductivity with Tc ~ 21.5 K was demonstrated in resistivity and magnetic susceptibility measurements after the as-grown crystals were annealed at 500 °C in vacuum for a week. X-ray diffraction patterns confirm that the annealed and the as-grown crystals possess the identical crystallographic structure of Ba2Ti2Fe2As4O. Energy-dispersive x-ray spectra indicate that partial Ti/Fe substitution exists in the [Fe2As2] layers and the annealing process redistributes the Ti within the Fe-plane. The ordered Fe-plane stabilized by annealing exhibits superconductivity with magnetic vortex pinned by Ti.

  1. Growth and Holographic Storage Properties of Fe:LiTaO3 Crystal

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Using Si-Mo bar as heater and doping Fe2O3 in LiTaO3, Fe∶LiTaO3 crystal was grown by Czochralski method. The curie temperature of the crystal was measured by thermal analyze method. The lattice constants of the crystal were calculated by measuring of X-ray spectra. The response time, exponential gain coefficient and diffraction efficiency of Fe:LiTaO3 were obtained by two wave coupled technique. Compared with Fe∶LiNbO3, the response time of Fe:LiTaO3 is six times shorter, the storage time of Fe:LiTaO3 is ten times longer and the photo scattering resistance ability of Fe:LiTaO3 is four times higher. Fe:LiTaO3 is an excellent holographic storage material.

  2. Dependence of ferroelectric and magnetic properties on measuring temperatures for polycrystalline BiFeO(3) films.

    Science.gov (United States)

    Naganuma, H; Inoue, Y; Okamura, S

    2008-05-01

    A multiferroic BiFeO(3) film was fabricated on a Pt/Ti/SiO(3)/Si(100) substrate by a chemical solution deposition (CSD) method, and this was followed by postdeposition annealing at 923 K for 10 min in air. X-ray diffraction analysis indicated the formation of the polycrystalline single phase of the BiFeO(3) film. A high remanent polarization of 89 microC/cm(2) was observed at 90 K together with a relatively low electric coercive field of 0.32 MV/cm, although the ferroelectric hysteresis loops could not be observed at room temperature due to a high leakage current density. The temperature dependence of the ferroelectric hysteresis loops indicated that these hysteresis loops lose their shape above 165 K, and the nominal remanent polarization drastically increased due to the leakage current. Magnetic measurements indicated that the saturation magnetization was less than 1 emu/cm(3) at room temperature and increased to approximately 2 emu/cm(3) at 100 K, although the spontaneous magnetization could not appear. The magnetization curves of polycrystalline BiFeO3 film were nonlinear at both temperatures, which is different with BiFeO3 single crystal.

  3. Hydrogenation of Laser-crystallized a-Si:H Films

    Directory of Open Access Journals (Sweden)

    M.V. Khenkin

    2015-10-01

    Full Text Available Ultrafast laser processing of semiconductors is a rapidly developing field of material science at the moment. In particular, femtosecond laser crystallization of amorphous hydrogenated silicon thin films has a big potential in photovoltaics. However laser treatment causes dehydrogenation process which decreases materials’ photosensitivity and thus limiting its application for optoelectronics. In present paper we studied photoelectric properties of laser-modified amorphous silicon films. Two different hydrogenation procedures were employed to restore films’ hydrogen content: keeping in hydrogen plasma and in high-pressure hydrogen atmosphere. The effectiveness of applied procedures for increasing materials’ photosensitivity is discussed.

  4. Nanocrystalline high-entropy alloy (CoCrFeNiAl 0.3 ) thin-film coating by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Weibing; Lan, Si; Gao, Libo; Zhang, Hongti; Xu, Shang; Song, Jian; Wang, Xunli; Lu, Yang

    2017-09-01

    High-entropy CoCrFeNiAl0.3 alloy thin films were prepared by magnetron sputtering technique. The thin film surface was very smooth and homogeneous. The synchrotron X-ray experiment confirmed that (111) type of texture existed in the thin film, and the structure was face-centered cubic nanocrystals with a minor content of ordered NiAl-type body-centered cubic structures. Interestingly, the elastic modulus of the thin film was nearly the same to the bulk single-crystal counterpart, however, the nanohardness is about four times of the bulk single-crystal counterpart. It was found that the high hardness was due to the formation of nanocrystal structure inside the thin films and the preferred growth orientation, which could be promising for applications in micro fabrication and advanced coating technologies.

  5. Electrodeposition of Pr-Fe alloy films in urea-dimethylsulfoxide

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hao; KE Qinfang; HUANG Kaisheng; LIU Guankun; YUAN Dingsheng

    2005-01-01

    Cyclic voltammetry and chronoamperometry were used to investigate the electrochemical behavior of Pr3+ ions electrochemical parameters were measured. Potentiostatic depositions between -1.6 and -2.4 V were applied to deposit Pr-Fe films in urea-DMSO mixed solution. The Pr content in the alloy films was in the range of 34.89 wt.% to 37.15 wt.%.The Pr-Fe alloy films are proven to be amorphous by XRD (X-ray diffraction).

  6. Perpendicular Magnetization Behavior of Low- Temperature Ordered FePt Films with Insertion of Ag Nanolayers

    Directory of Open Access Journals (Sweden)

    Da-Hua Wei

    2016-03-01

    Full Text Available FePt-Ag nanocomposite films with large perpendicular magnetic anisotropy have been fabricated by alternate-atomic-layer electron beam evaporation onto MgO(100 substrates at the low temperature of 300 °C. Their magnetization behavior and microstructure have been studied. The surface topography was observed and varied from continuous to nanogranular microstructures with insertion of Ag nanolayers into Fe/Pt bilayer films. The measurement of angular-dependent coercivity showed a tendency of the domain-wall motion as a typical peak behavior shift toward more like a coherent Stoner-Wohlfarth rotation type with the insertion of Ag nanolayers into the FePt films. On the other hand, the inter-grain interaction was determined from a Kelly-Henkel plot. The FePt film without insertion of Ag nanolayers has a positive δM, indicating strong exchange coupling between neighboring grains, whereas the FePt film with insertion of Ag nanolayers has a negative δM, indicating that inter-grain exchange coupling is weaker, thus leading to the presence of dipole interaction in the FePt–Ag nanogranular films. The magnetic characteristic measurements confirmed that the perpendicular magnetization reversal behavior and related surface morphology of low-temperature-ordered FePt(001 nanogranular films can be systematically controlled by the insertion of Ag nanolayers into the FePt system for next generation magnetic storage medium applications.

  7. 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...

  8. Size effects in single crystal thin films : nonlocal crystal plasticity simulations

    NARCIS (Netherlands)

    Yefimov, S; van der Giessen, E

    2005-01-01

    Stress relaxation in single crystalline thin films on substrates subjected to thermal loading is studied using a recently proposed nonlocal continuum crystal plasticity theory. The theory is founded on a statistical-mechanics description of the collective behaviour of dislocations in multiple slip,

  9. Antiferromagnetic coupling between spinel ferrite and {alpha}-Fe layers in Fe{sub 3-{delta}O4}/MgO/Fe(0 0 1) epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Yanagihara, Hideto; Toyoda, Yuta; Kita, Eiji [Institute of Applied Physics, University of Tsukuba, Ibaraki 305-8573 (Japan)

    2011-02-16

    We have investigated interlayer exchange coupling (IEC) in epitaxial films of both Fe{sub 3}O{sub 4}/MgO/Fe(0 0 1) and {gamma}-Fe{sub 2}O{sub 3}/MgO/Fe(0 0 1). Depending on the thickness of the MgO spacer, both systems exhibit strong antiferromagnetic IEC of -1 to -2 erg cm{sup -2}. The {gamma}-Fe{sub 2}O{sub 3}/MgO/Fe(0 0 1) trilayer exhibits the strongest IEC when the thickness of the MgO spacer is approximately 7 A, whereas the Fe{sub 3}O{sub 4}/MgO/Fe(0 0 1) trilayer exhibits the strongest IEC when the thickness of the MgO spacer is zero. The results suggest that two different types of exchange coupling exist in the magnetic trilayers which consist of metallic iron and spinel ferrite layers.

  10. Effect of Vacuum Annealing on Superconductivity in Fe(Se,Te) Single Crystals

    OpenAIRE

    Komiya, Seiki; Hanawa, Masafumi; Tsukada, Ichiro; Maeda, Atsutaka

    2013-01-01

    The effect of vacuum annealing on superconductivity is investigated in Fe(Se,Te) single crystals. It is found that superconductivity is not enhanced by annealing under high vacuum (~ 10^(-3) Pa) or by annealing in a sealed evacuated quartz tube. In a moderate vacuum atmosphere (~ 1 Pa), iron oxide layers are found to show up on sample surfaces, which would draw excess Fe out of the crystal. Thus, it is suggested that remanent oxygen effectively works to remove excess Fe from the matrix of Fe(...

  11. Magnetic anisotropy and microscopy studies in magnetostrictive Tb-(Fe,Co) thin films

    Science.gov (United States)

    Umadevi, K.; Talapatra, A.; Arout Chelvane, J.; Palit, Mithun; Mohanty, J.; Jayalakshmi, V.

    2017-08-01

    This paper reports the effect of the film thickness on the magnetostrictive behavior of (Fe,Co) rich Tb-(Fe,Co) films grown on Si ⟨100⟩ by electron beam evaporation. Magnetostriction was found to decrease with an increase in film thicknesses. To understand the variation of magnetostriction with the film thickness, detailed structural, microstructural, magnetization, and magnetic microscopy studies were carried out. X-ray diffraction studies indicated the presence of two phases, viz., Tb2 (Fe, Co)17 and Fe-Co phases, for all the films. With the increase in the film thickness, the peak intensity of the Tb2 (Fe, Co)17 phase decreased and that of the Fe-Co phase increased. Magnetization studies showed the presence of strong in-plane anisotropy for all the films. In addition to this, the presence of the out-of-plane component of magnetization was also observed for the films grown with higher thicknesses. This anisotropic behavior was also validated through magnetic microscopy studies carried out along the in-plane and out-of-plane directions employing magneto-optic Kerr microscopy and magnetic force microscopy, respectively. The decrease in magnetostriction was explained on the basis of dual phase formation and complex interplay between the in-plane and out-of-plane magnetic anisotropies present in the film.

  12. Enhancement of order degree and perpendicular magnetic anisotropy of L10 ordered Fe(Pt,Pd) alloy film by introducing a thin MgO cap-layer

    Science.gov (United States)

    Noguchi, Youhei; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi; Inaba, Nobuyuki

    2016-07-01

    Fe50PtxPd50-x (at%, x=0-50) alloy films of 10 nm thickness with and without 2-nm-thick MgO cap-layers are prepared on MgO(001) single-crystal substrates by employing a two-step method consisting of low-temperature deposition at 200 °C followed by high-temperature annealing at 600 °C. The influences of MgO cap-layer on the structure and the magnetic properties are investigated. Fe50PtxPd50-x films epitaxially grow on the substrates at 200 °C. The Fe50Pd50 and the Fe50Pt12.5Pd37.5 films are respectively composed of (001) single-crystals with disordered fcc-based (A1) and bcc-based (A2) structures. The films with x>25 consist of mixtures of A1 and A2 crystals. The volume ratio of A2 to A1 crystal decreases with increasing the x value from 25 to 50. The in-plane and out-of-plane lattices are respectively expanded and shrunk due to accommodation of lattice mismatch between film and substrate. When the films are annealed at 600 °C, phase transformation to L10 ordered phase takes place. L10 phase transformation of Fe50PtxPd50-x film is promoted for a sample with MgO cap-layer and the order degree is higher than that without cap-layer. Furthermore, L10 ordering with the c-axis perpendicular to the substrate surface is enhanced for the film with cap-layer. The cap-layer is considered to be giving a tension stress to the magnetic film in lateral direction which promotes L10 ordering with the c-axis perpendicular to the substrate. Deposition of cap-layer is shown effective in achieving higher order degree and in enhancing perpendicular magnetic anisotropy with Fe(Pt,Pd) films.

  13. Nanocrystalline silicon films prepared by laser-induced crystallization

    Institute of Scientific and Technical Information of China (English)

    傅广生; 于威; 李社强; 侯海虹; 彭英才; 韩理

    2003-01-01

    The excimer laser-induced crystallization technique has been used to investigate the preparation of nanocrystalline silicon (nc-Si) from amorphous silicon (α-Si) thin films on silicon or glass substrates. The α-Si films without hydrogen grown by pulsed-laser deposition are chosen as precursor to avoid the problem of hydrogen effluence during annealing.Analyses have been performed by scanning electron microscopy, atomic force microscopy, Raman scattering spectroscopy and high-resolution transmission-electron microscopy. Experimental results show that silicon nanocrystals can be formed through laser annealing. The growth characters of nc-Si are strongly dependent on the laser energy density. It is shown that the volume of the molten silicon predominates essentially the grain size of nc-Si, and the surface tension of the crystallized silicon is responsible for the mechanism of nc-Si growth.

  14. Enhancement of L10 ordering with the c-axis perpendicular to the substrate in FePt alloy film by using an epitaxial cap-layer

    Science.gov (United States)

    Ohtake, Mitsuru; Nakamura, Masahiro; Futamoto, Masaaki; Kirino, Fumiyoshi; Inaba, Nobuyuki

    2017-05-01

    FePt alloy thin films with cap-layers of MgO or C are prepared on MgO(001) single-crystal substrates by using a two-step method consisting of low-temperature deposition at 200 °C followed by high-temperature annealing at 600 °C. The FePt film thickness is fixed at 10 nm, whereas the cap-layer thickness is varied from 1 to 10 nm. The influences of cap-layer material and cap-layer thickness on the variant structure and the L10 ordering are investigated. Single-crystal FePt(001) films with disordered fcc structure (A1) grow epitaxially on the substrates at 200 °C. Single-crystal MgO(001) cap-layers grow epitaxially on the FePt films, whereas the structure of C cap-layers is amorphous. The phase transformation from A1 to L10 occurs when the films are annealed at 600 °C. The FePt films with MgO cap-layers thicker than 2 nm consist of L10(001) variant with the c-axis perpendicular to the substrate surface, whereas those with C cap-layers involve small volumes of L10(100) and (010) variants with the c-axis lying in the film plane. The in-plane and the out-of-plane lattices are respectively more expanded and contracted in the continuous-lattice MgO/FePt/MgO structure due to accommodations of misfits of FePt film with respect to not only the MgO substrate but also the MgO cap-layer. The lattice deformation promotes phase transformation along the perpendicular direction and L10 ordering. The FePt films consisting of only L10(001) variant show strong perpendicular magnetic anisotropies and low in-plane coercivities. The present study shows that an introduction of epitaxial cap-layer is effective in controlling the c-axis perpendicular to the substrate surface.

  15. Structure and Magnetic Properties of Fe-N Films Prepared by Dual Ion Beam Sputtering

    Institute of Scientific and Technical Information of China (English)

    诸葛兰剑; 吴雪梅; 汤乃云; 叶春兰; 姚伟国

    2001-01-01

    Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is of the films were investigated by a vibrating sample magnetometer (VSM). The structure of the films is insensitive to the ratios of N2/Ar in main ion source(MIS), and is mainly influenced by the substrate temperature (Ts).``

  16. Study on Characteristics of Crystal Growth of NdFeB Cast Alloys

    Institute of Scientific and Technical Information of China (English)

    李波; 郭炳麟; 王东玲; 刘涛; 喻晓军

    2004-01-01

    The characteristic of crystal growth of NdFeB cast alloys was studied.It is found that the crystal growth orientation of conventional ingots is along or .As the cooling rate increases,the crystallization orientation changes from a axis to c axis,along which the grain is easy to be magnetized.Meanwhile,by analyzing the change of crystallization orientation,the influence on the property of magnets was discussed.

  17. Photonic Crystal Cavities in Cubic Polytype Silicon Carbide Films

    CERN Document Server

    Radulaski, Marina; Buckley, Sonia; Rundquist, Armand; Provine, J; Alassaad, Kassem; Ferro, Gabriel; Vučković, Jelena

    2013-01-01

    We present the design, fabrication, and characterization of high quality factor and small mode volume planar photonic crystal cavities from cubic (3C) thin films (thickness ~ 200 nm) of silicon carbide (SiC) grown epitaxially on a silicon substrate. We demonstrate cavity resonances across the telecommunications band, with wavelengths from 1250 - 1600 nm. Finally, we discuss possible applications in nonlinear optics, optical interconnects, and quantum information science.

  18. Role of the Confined Geometry on the Crystallization of Poly(ethylene terephthlate) Ultrathin Films

    Institute of Scientific and Technical Information of China (English)

    Ying ZHANG; Yong Lai LU; De Yan SHEN

    2005-01-01

    The reflection-absorption infrared (RAIR) was employed to study the crystallization kinetic of poly (ethylene terephthalate) (PET) ultrathin films. During isothermal crystallization the thinner PET film shows a slower kinetic compared with the thicker film. Moreover, the final crystallinity of films with various thickness was found decrease with thickness. The result of fitting our data to Avrami equation showed that the Avrami exponents decrease with film thickness.

  19. Low-field microwave absorption in pulse laser deposited FeSi thin film

    Energy Technology Data Exchange (ETDEWEB)

    Gavi, H. [Department of Physics, SARCHI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0028 (South Africa); Ngom, B.D. [Groupe d Laboratoires de Physique des Solid et des Materiaux, Faculte deSciences et Techniques, Universite Cheikh Anta de Dakar, BP 25114 Dakar-Fann, Daka 16996 (Senegal); Institut National de la Recherche Scientifique Centre-Energie Materiaux, Telecommunications 1650, Boulevard Lionel Boulet Varennes (Quebec), Canada J3X 1S2 (Canada); Beye, A.C. [Groupe d Laboratoires de Physique des Solid et des Materiaux, Faculte deSciences et Techniques, Universite Cheikh Anta de Dakar, BP 25114 Dakar-Fann, Daka 16996 (Senegal); Strydom, A.M. [Department of Physics, University of Johannesburg, Johannesburg 2006 (South Africa); Srinivasu, V.V., E-mail: vallavs@unisa.ac.za [Department of Physics, University of South Africa, Pretoria 0003 (South Africa); Chaker, M. [Institut National de la Recherche Scientifique Centre-Energie Materiaux, Telecommunications 1650, Boulevard Lionel Boulet Varennes (Quebec), Canada J3X 1S2 (Canada); Manyala, N., E-mail: ncholu.manyala@up.ac.za [Department of Physics, SARCHI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0028 (South Africa)

    2012-03-15

    Low field microwave absorption (LFMA) measurements at 9.4 GHz (X-band), were carried out on pulse laser deposited (PLD) polycrystalline B20 cubic structure FeSi thin film grown on Si (111) substrate. The LFMA properties of the films were investigated as a function of DC field, temperature, microwave power and the orientation of DC field with respect to the film surface. The LFMA signal is very strong when the DC field is parallel to the film surface and vanishes at higher angles. The LFMA signal strength increases as the microwave power is increased. The LFMA signal disappears around 340 K, which can be attributed to the disappearance of ferromagnetic state well above room temperature in these films. We believe that domain structure evolution in low fields, which in turn modifies the low field permeability as well as the anisotropy, could be the origin of the LFMA observed in these films. The observation of LFMA opens the possibility of the FeSi films to be used as low magnetic field sensors in the microwave and rf frequency regions. - Highlights: Black-Right-Pointing-Pointer B20 crystalline FeSi thin film shows low field microwave absorption. Black-Right-Pointing-Pointer Usual ferromagnic resonance typical of magnetic materials is observed in FeSi film. Black-Right-Pointing-Pointer FeSi film can be used for low magnetic field sensors.

  20. Microstructures and magnetic properties of L1{sub 0} FePt films deposited on NaCl-type films

    Energy Technology Data Exchange (ETDEWEB)

    Sun, T.H., E-mail: s9931829@m99.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Chen, S.C.; Su, W.H. [Department of Materials Engineering and Center for Thin Film Technologies and Applications, Ming Chi University of Technology, Taipei 24301, Taiwan (China); Chen, J.R. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2013-10-01

    A single-layered FePt film of 30 nm thickness with perpendicular magnetic anisotropy is achieved by depositing the film onto a heated Si(100) substrate at 620 °C. Its perpendicular coercivity (Hc{sub ⊥}), saturation magnetization (M{sub s}) and perpendicular squareness (S{sub ⊥}) are as high as 1113 kA/m, 0.594 Wb/m{sup 2} and 0.96, respectively. The perpendicular magnetic anisotropy degrades when a 5-nm NiO film is introduced under this single-layered film. Upon further increasing the thickness of the NiO film to 10 nm, the Hc{sub ⊥} of the single-layered film decreases greatly to around 330 kA/m. Compared to a NiO underlayer, the Hc{sub ⊥} of the FePt film remains above 1000 kA/m when a 10-nm MgO underlayer is introduced. Furthermore, when the thickness of the MgO underlayer is decreased to 5 nm, the perpendicular magnetic anisotropy of the single-layered FePt film is further enhanced. Its Hc{sub ⊥} stays high at 1081 kA/m; however, S{sub ⊥} increases significantly to 1. - Highlights: ► A thin MgO underlayer enhances the perpendicular magnetic anisotropy of FePt film. ► A NiO underlayer degrades the perpendicular magnetic anisotropy of the film. ► Ni atoms diffuse from NiO underlayer into FePt layer forming NiFe compounds.

  1. Holographic Storage Properties of In:Fe:Mn:LiNbO3 Crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In:Fe:Mn:LiNbO3(LN) crystals were grown in air atmosphere by Czochralski method with different concentration of In (0, 1, 2, 3 mol%) in the melts, while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%, respectively. The location of doping ions was analyzed by Ultravioletvisible absorption spectra and differential thermal analysis. The diffraction efficiency (η), writing time (τw) and erasure time (τe) of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt, the absorption edge of In:Fe:Mn:LN crystal shifts to the violet firstly and then makes the Einstein shift, the Curie temperature of crystal increases firstly and then decreases, the storage ratio speeds up, diffraction efficiency decreases, and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In:Fe:Mn:LN crystal with different doping concentration of In3+ was investigated, suggesting the In:Fe:Mn:LN crystals are excellent holographic storage materiel with better synthetical properties than Fe:Mn:LN crystals.

  2. Preparation and characterization of CoFe2O4/TiO2 magnetic composite films

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    CoFe2O4/TiO2 magnetic composite films were prepared using the sol-gel method with tetrabutyltitanate and metallic chlorates as starting materials. The effects of heat treatment temperatures on micro- structures and on magnetic properties were studied. The microstructure and properties of the samples at different heat treatment temperatures were characterized by X-ray diffraction, Raman spectrum, scanning electron microscopy, polarized microscopy and vibrating sample magnetometry. The results show that crystals of different substances grow up independently. Cobalt ferrite is evenly embedded into the titanium dioxide matrix in the prepared composite films. The magnetism of the composite films is enhanced with an increase of the heat temperature.

  3. Crystallization mechanism of CeAlFeCo bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    王志新; 卢金斌; 席艳君

    2010-01-01

    Crystallization behaviors of Ce60Al15Fe5+xCo20-x(x=0,5,10) bulk metallic glasses(BMGs) were studied by means of differential scanning calorimeter(DSC) and X-ray diffraction(XRD).The crystallization processes of different samples were simulated by JMA equation.Experimental results demonstrated that incubation and crystallization time increased with decreasing isothermal temperature for the same sample.The crystallization mechanism of CeAlFeCo BMGs was discussed.

  4. Nano-structure analysis of Fe implanted SnO2 films by 57Fe and 119Sn CEMS

    Science.gov (United States)

    Nomura, Kiyoshi; Reuther, Helfried

    2009-06-01

    SnO2 films were implanted with 57Fe at substrate temperatures of room temperature and 300°C. The chemical states of Fe and Sn were characterized by 57Fe CEMS and 119Sn CEMS, respectively. The implanted Fe species exist as Fe(II) and Fe(III) in SnO2 films, which also are reduced into Sn(II)on the implanted surface. The as prepared and post annealed at 500°C samples did not show Kerr effect, but the sample implanted with 1 × 1017 Fe ions/cm2 at 300°C showed Kerr effect although magnetic sextets were not clearly observed in the 57Fe CEM spectra. The Kerr effect disappeared after annealing. It suggests that the number of magnetic defects decreases by absorption of oxygen. Magnetic relaxation appeared in the case of low implantation of 5 × 1016 Fe ions/cm2, which is considered to be due to anti-ferromagnetism or paramagnetic relaxation.

  5. Influence of Fe Buffer Layer on Co-Doped BaFe2As2 Superconducting Thin Films

    Directory of Open Access Journals (Sweden)

    C. Bonavolontà

    2015-01-01

    Full Text Available A systematic characterization of Co-doped BaFe2As2 (Ba-122 thin films has been carried out. Two samples were available, one grown on CaF2 substrate and the other on MgO with an Fe buffer layer. The goal was to investigate films’ magnetic and superconducting properties, their reciprocal interplay, and the role played by the Fe buffer layer in modifying them. Morphological characterization and Energy Dispersive X-ray analyses on the Fe-buffered sample demonstrate the presence of diffused Fe close to the Co-doped Ba-122 outer surface as well as irregular holes in the overlying superconducting film. These results account for hysteresis loops obtained with magneto-optic Kerr effect measurements and observed at both room and low temperatures. The magnetic pattern was visualized by magneto-optical imaging with an indicator film. Moreover, we investigated the onset of superconductivity through a measure of the superconducting energy gap. The latter is strictly related to the decay time of the excitation produced by an ultrashort laser pulse and has been determined in a pump-probe transient reflectivity experiment. A comparison of results relative to Co-doped Ba-122 thin films with and without Fe buffer layer is finally reported.

  6. Effect of Applied Current Density on Morphological and Structural Properties of Electrodeposited Fe-Cu Films

    Institute of Scientific and Technical Information of China (English)

    Umut Sarac; M. Celalettin Baykul

    2012-01-01

    A detailed study has been carried out to investigate the effect of applied current density on the composition, crystallographic structure, grain size, and surface morphology of Fe-Cu films. X-ray diffraction (XRD) results show that the films consist of a mixture of face-centered cubic (fcc) Cu and body centered cubic (bcc) ~-Fe phases. The average crystalline size of both Fe and Cu particles decreases as the applied current density becomes more negative. Compositional analysis of Fe-Cu films indicates that the Fe content within the films increases with decreasing current density towards more negative values. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used to investigate the surface morphology of Fe-Cu films. It is observed that the surface morphology of the films changes from dendritic structure to a cauliflower structure as the applied current density becomes more negative. The surface roughness and grain size of the Fe-Cu films decrease with decreasing applied current density towards more negative values.

  7. Effect of annealing temperature on multiferroic properties of Bi0.85Nd0.15FeO3 thin films prepared by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    GOTO; Takashi

    2010-01-01

    Bi0.85Nd0.15FeO3 films were prepared on Pt/Ti/SiO2/Si substrate by a sol-gel method,and annealed at different temperatures.The effect of annealing temperature on the crystal structure,dielectric,ferroelectric,and ferromagnetic properties was investigated.When the Bi0.85Nd0.15FeO3 films were annealed at 490-600°C,the single phase was obtained.Bi0.85Nd0.15FeO3 film annealed at 600°C showed good multiferroic properties with εr of 145 (at 1 MHz),Ms of 44.8 emu/cm3,and 2Pr of 16.6 μC/cm2.

  8. Structure and magnetic properties of amorphous and polycrystalline Fe3O4 thin films

    Institute of Scientific and Technical Information of China (English)

    TANG Xiao-li; ZHANG Huai-wu; SU Hua; ZHONG Zhi-yong; JING Yu-lan

    2006-01-01

    Half-metallic Fe3O4 films prepared by DC magnetron reactive sputtering with a tantalum(Ta) buffer layer was investigated. Primary emphasis is placed on the structural impact on its magnetic properties. The experimental results show that the amorphous Fe3O4 films exhibit a superparamagnetic response at a large-scale from 20 nm to 150 nm,and the magnetoresistance (MR) isn't detected. By contrast,the polycrystalline Fe3O4 films possess large saturation magnetization Ms of 420 A/(kg-cm) and a clear magnetoresistance with a field of 40 kA/m. The unusual properties for the amorphous Fe3O4 film are attributed to the existing large density of the similar structure as anti-phase boundaries in the film.

  9. Influence of microstructure on the corrosion resistance of Fe-44Ni thin films

    Science.gov (United States)

    Lu, Lin; Liu, Tian-cheng; Li, Xiao-gang

    2016-06-01

    An Fe-44Ni nanocrystalline (NC) alloy thin film was prepared through electrodeposition. The relation between the microstructure and corrosion behavior of the NC film was investigated using electrochemical methods and chemical analysis approaches. The results show that the NC film is composed of a face-centered cubic phase (γ-(Fe,Ni)) and a body-centered cubic phase (α-(Fe,Ni)) when it is annealed at temperatures less than 400°C. The corrosion resistance increases with the increase in grain size, and the corresponding corrosion process is controlled by oxygen reduction. The NC films annealed at 500°C and 600°C do not exhibit the same pattern, although their grain sizes are considerably large. This result is attributed to the existence of an anodic phase, Fe0.947Ni0.054, in these films. Under this condition, the related corrosion process is synthetically controlled by anodic dissolution and depolarization.

  10. Thin aligned organic polymer films for liquid crystal devices

    CERN Document Server

    Foster, K E

    1997-01-01

    This project was designed to investigate the possibility of producing alignment layers for liquid crystal devices by cross-linking thin films containing anisotropic polymer bound chromophores via irradiation with polarised ultraviolet light. Photocross-linkable polymers find use in microelectronics, liquid crystal displays, printing and UV curable lacquers and inks; so there is an increasing incentive for the development of new varieties of photopolymers in general. The synthesis and characterisation of two new photopolymers that are suitable as potential alignment layers for liquid crystal devices are reported in this thesis. The first polymer contains the anthracene chromophore attached via a spacer unit to a methacrylate backbone and the second used a similarly attached aryl azide group. Copolymers of the new monomers with methyl methacrylate were investigated to establish reactivity ratios in order to understand composition drift during polymerisation.

  11. Applications of thin-film sandwich crystallization platforms.

    Science.gov (United States)

    Axford, Danny; Aller, Pierre; Sanchez-Weatherby, Juan; Sandy, James

    2016-04-01

    Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal sample intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.

  12. Columnar structured FePt films epitaxially grown on large lattice mismatched intermediate layer

    Science.gov (United States)

    Dong, K. F.; Deng, J. Y.; Peng, Y. G.; Ju, G.; Chow, G. M.; Chen, J. S.

    2016-09-01

    The microstructure and magnetic properties of the FePt films grown on large mismatched ZrN (15.7%) intermediate layer were investigated. With using ZrN intermediate layer, FePt 10 nm films exhibited (001) texture except for some weaker FePt (110) texture. Good epitaxial relationships of FePt (001) //ZrN (001) //TiN (001) among FePt and ZrN/TiN were revealed from the transmission electron microscopy (TEM) results. As compared with TiN intermediate layer, although FePt-SiO2-C films grown on ZrN/TiN intermediate layer showed isotropic magnetic properties, the large interfacial energy and lattice mismatch between FePt and ZrN would lead to form columnar structural FePt films with smaller grain size and improved isolation. By doping ZrN into the TiN layer, solid solution of ZrTiN was formed and the lattice constant is increased comparing with TiN and decreased comparing with ZrN. Moreover, FePt-SiO2-C films grown on TiN 2 nm-20 vol.% ZrN/TiN 3 nm intermediate layer showed an improved perpendicular magnetic anisotropy. Simultaneously, columnar structure with smaller grain size retained.

  13. The local structure and ferromagnetism in Fe-implanted SrTiO3 single crystals

    Science.gov (United States)

    Lobacheva, O.; Chavarha, M.; Yiu, Y. M.; Sham, T. K.; Goncharova, L. V.

    2014-07-01

    We report a connection between the local structure of low-level Fe impurities and vacancies as the cause of ferromagnetic behavior observed in strontium titanate single crystals (STO), which were implanted with Fe and Si ions at different doses then annealed in oxygen. The effects of Fe doping and post-implantation annealing of STO were studied by X-ray Absorption Near Edge Structure (XANES) spectroscopy and Superconducting Quantum Interference Device magnetometry. XANES spectra for Fe and Ti K- and L-edge reveal the changes in the local environment of Fe and Ti following the implantation and annealing steps. The annealing in oxygen atmosphere partially healed implantation damages and changed the oxidation state of the implanted iron from metallic Fe0 to Fe2+/Fe3+ oxide. The STO single crystals were weak ferromagnets prior to implantation. The maximum saturation moment was obtained after our highest implantation dose of 2 × 1016 Fe atom/cm2, which could be correlated with the metallic Fe0 phases in addition to the presence of O/Ti vacancies. After recrystallization annealing, the ferromagnetic response disappears. Iron oxide phases with Fe2+ and Fe3+ corresponding to this regime were identified and confirmed by calculations using Real Space Multiple Scattering program (FEFF9).

  14. 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.

  15. 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.

  16. Magnetic x-ray linear dichroism of ultrathin Fe-Ni alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, F.O.; Willis, R.F. [Pennsylvania State Univ., University Park, PA (United States); Goodman, K.W. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors have studied the magnetic structure of ultrathin Fe-Ni alloy films as a function of Fe concentration by measuring the linear dichroism of the 3p-core levels in angle-resolved photoemission spectroscopy. The alloy films, grown by molecular-beam epitaxy on Cu(001) surfaces, were fcc and approximately four monolayers thick. The intensity of the Fe dichroism varied with Fe concentration, with larger dichroisms at lower Fe concentrations. The implication of these results to an ultrathin film analogue of the bulk Invar effect in Fe-Ni alloys will be discussed. These measurements were performed at the Spectromicroscopy Facility (Beamline 7.0.1) of the Advanced Light Source.

  17. Thin-Film Behavior of Poly(methyl methacrylates). 3. Epitaxial Crystallization in Thin Films of Isotactic Poly(methyl methacrylate) Using Crystalline Langmuir-Blodgett Layers

    NARCIS (Netherlands)

    Brinkhuis, R.H.G.; Schouten, A.J.

    1992-01-01

    A procedure is introduced using monolayer crystallized films of isotactic poly(methyl methacrylate) (i-PMMA) to induce crystallization in amorphous films of i-PMMA. Use of the Langmuir-Blodgett films as surface crystallization nuclei permits the preparation of highly crystalline films with thickness

  18. Mercury-induced crystallization and SAD phasing of the human Fe65-PTB1 domain

    OpenAIRE

    Radzimanowski, Jens; Ravaud, Stéphanie; Beyreuther, Konrad; Sinning, Irmgard; Wild, Klemens

    2008-01-01

    Crystals of the phosphotyrosine-binding domain 1 (PTB1) of the neuronal adaptor protein Fe65 grown in the presence of a mercury derivative show a dramatic improvement in resolution, permitting SAD phasing.

  19. Superconducting properties of “111” type LiFeAs iron arsenide single crystals

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    LiFeAs single crystal has been grown with superconducting transition temperature Tc comparable to that of polycrystals.A magnetic transition is found at about 160 K,which suggests the correlation of superconductivity with spin wave density.

  20. Green laser crystallization of GeSi thin films and dopant activation

    NARCIS (Netherlands)

    Rangarajan, Balaji; Brunets, Ihor; Oesterlin, Peter

    2011-01-01

    Laser-crystallization of amorphous $Ge_{0.85}Si_{0.15}$ films is studied, using green laser scanning and preformed topography to steer the crystallization. Large crystals (8x2 $\\mu m^2$) are formed with location-controlled grain boundaries. The obtained films were characterized using Scanning Electr

  1. Novel Bi-substituted Yttrium Iron Garnet Film/Crystal Composite for Magneto-optical Applications

    Institute of Scientific and Technical Information of China (English)

    HUANG Min; XU Zhi-cheng; ZHOU Wei-zhen

    2004-01-01

    The novel Bi-substituted rare-earth iron garnet films were grown by the modified liquid phase epitaxy (LPE) technique for use as a 45° Faraday rotator in optical isolators. First, single crystals of Y3 Fe5 O12(YIG), with a lattice constant of 1. 237 8 nm, were grown by means of the Czochralski method. Using the seed crystal of YIG instead of the conventional non-magnetic garnet of Gd3Ga5O12 (GGG) as a substrate,a film of BiYbIG was grown by means of the LPE method from Bi2O3 - B2O3 fluxes. The structural, magnetic and magneto-optical properties of BiYbIG LPE film/YIG crystal composite have been investigated using directional X-ray diffraction (XRD), electron probe microanalysis (EPMA), vibrating sample magnetometer (VMS) and near-infrared transmission spectrometry. The saturation magnetization 4πMs has been estimated to be about 1.2×10 6 A/m. The Faraday rotation spectrum was measured by the method of rotating analyzer ellipsometry (RAE) with the wavelength varied from 800 nm to 1 700 nm. The resultant Bi0.37 Yb2.63 Fe5 O12LPE film/YIG crystal composite showed an increased Faraday rotation coefficient due to doping Bi3+ ions into the dodecahedral sites of the magnetic garnet without increasing absorption loss, therefore a good magnetooptic figure of merit,defined by the ratio of Faraday rotation and optical absorption loss, has been achieved of 21.5 and 30.2 (°)/dB at 1 300 and 1 550 nm wavelengths respectively and room temperature. Since Yb3+ and Y3+ ions provide the opposite contribution to the wideband and temperature characteristics of Faraday rotation,the values of Faraday rotation wavelength and temperature coefficients were reduced to 0.06 %/nm and 0.007(°)/℃ at 1 550 nm wavelength, respectively.

  2. Study on micro-structure and morphological evolution of Fe/Pt nano-magnetic film.

    Science.gov (United States)

    Ishiguro, S; Ju, D Y; Ogatsu, R; Nakano, T

    2011-10-01

    One of the vertical magnetic recordings medium materials of the hard disk drive (HDD) is a Fe/Pt thin film. The development of ultra-high density magnetic recording medium in next generation is expected the magnetic disks such as HDD with capacity enlargement of the data. In order to study effectiveness of the proposed sputtering method, we evaluated micro structure, magnetic and the mechanical properties of a Fe/Pt thin film by some sputtering process conditions. From research results, effect sputtering conditions on micro-structure and mechanical properties of Fe/Pt nano film are verified.

  3. 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%.

  4. Effects of ultrasonic field in pulse electrodeposition of NiFe film on Cu substrate

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, R. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia); Yow, H.K. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia)], E-mail: hkyow@mmu.edu.my; Ong, B.H. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia); Manickam, R. [Electronics Faculty, Tyndale Education Group Pte Ltd., 188942 (Singapore); Saaminathan, V. [School of Material Science and Engineering, Nanyang Technological University, 639798 (Singapore); Tan, K.B. [Department of Chemistry, Universiti Putra Malaysia, Serdang, 43400 (Malaysia)

    2009-07-29

    NiFe film was pulse electrodeposited on conductive Cu substrate under galvanostatic mode in the presence of an ultrasonic field. The NiFe film electrodeposited was subjected to structural and surface analyses by X-ray diffraction, energy dispersive X-ray spectroscopy, surface profiling and scanning electron microscopy, respectively. The results show that the ultrasonic field has significantly improved the surface roughness, reduced the spherical grain size in the range from 490-575 nm to 90-150 nm, and increased the Ni content from 76.08% to 79.74% in the NiFe film electrodeposited.

  5. Localization correction to the anomalous Hall effect in amorphous CoFeB thin films

    Institute of Scientific and Technical Information of China (English)

    丁进军; 吴少兵; 杨晓非; 朱涛

    2015-01-01

    An obvious weak localization correction to anomalous Hall conductance (AHC) in very thin CoFeB film is reported. We find that both the weak localization to AHC and the mechanism of anomalous Hall effect are related to the CoFeB thickness. When the film is thicker than 3 nm, the side jump mechanism dominates and the weak localization to AHC vanishes. For very thin CoFeB films, both the side jump and skew scattering mechanisms contribute to the anomalous Hall effect, and the weak localization correction to AHC is observed.

  6. 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.

  7. Controllable magnetic and magnetostrictive properties of FeGa films electrodeposited on curvature substrates

    Science.gov (United States)

    Cao, Derang; Wang, Zhenkun; Pan, Lining; Feng, Hongmei; Cheng, Xiaohong; Zhu, Zengtai; Wang, Jianbo; Liu, Qingfang; Han, Genliang

    2016-11-01

    Magnetic properties of magnetostrictive FeGa films deposited by electrodeposition method on flexible curvature substrates were investigated under various mechanical stresses. The stresses of the bowed substrates were realized by series of different concentric circles. FeGa films exhibit a significant uniaxial magnetic anisotropy after the application of tensile or compressive stress, and the anisotropy of the film can be regulated by the residual stress. In addition, the magnetostriction of FeGa films is estimated through approximate calculation, indicating that the saturation magnetostrictive constant of films is enhanced with the increased tensile and compressive strains. These results provide another way to tune the magnetic properties and magnetostriction of flexible thin films, which is particularly important for the development of the flexible magneto-electronic devices.

  8. PREPARATION AND PROPERTIES OF Ni-Cr AND Fe-Cr-Al FILMS BY VACUUM EVAPORATION

    Institute of Scientific and Technical Information of China (English)

    X. W. Shi; Z.Y. Liu; D.C. Zeng; C.M. Li

    2003-01-01

    Ni-Cr and Fe-Cr-Al films deposited on the Al2O3 substrate are studied by a method of vacuum evaporation in this paper. Influence of resistance value on density and evaporation parameters of the films reveals that the resistance of films and the adhesion of films to substrates are determined by the evaporation time and the substrate temperate under the condition of the maximum vacuity of 6.2×10-4 pa, respectively.

  9. Synthesis of tetragonal mackinawite-type FeS nanosheets by solvothermal crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Sines, Ian T.; Vaughn II, Dimitri D. [Pennsylvania State University, Department of Chemistry, 104 Chemistry Building, University Park, PA 16802 (United States); Misra, Rajiv [Pennsylvania State University, Department of Physics, University Park, PA 16802 (United States); Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Popczun, Eric J. [Pennsylvania State University, Department of Chemistry, 104 Chemistry Building, University Park, PA 16802 (United States); Schaak, Raymond E., E-mail: schaak@chem.psu.edu [Pennsylvania State University, Department of Chemistry, 104 Chemistry Building, University Park, PA 16802 (United States); Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States)

    2012-12-15

    Mackinawite, a metastable 1:1 compound of iron and sulfur that adopts an anti-PbO-type structure, is of interest because of its relationship to known iron chalcogenide superconductors, as well as its biogeochemical relevance. Colloidal nanosheets of mackinawite-type FeS were synthesized by first generating an amorphous Fe-S precursor via the aqueous room-temperature co-precipitation of Fe{sup 2+} and S{sup 2-}, then solvothermally crystallizing it in ethylene glycol at 200 Degree-Sign C in an autoclave. The product is highly crystalline, with lattice constants of a=3.674(3) A and c=5.0354(3) A. The nanosheets, with their surface normal oriented along the [0 0 1] direction, are irregularly faceted with edge lengths that range from 100 nm to over 1 {mu}m and average thicknesses of approx. 30 nm. The samples showed a ferromagnetic background signal with no evidence of superconductivity. - Grahpical abstract: Single-crystal colloidal nanosheets of mackinawite-type FeS were synthesized by the solvothermal crystallization of an amorphous Fe-S precursor. Highlights: Black-Right-Pointing-Pointer Aqueous co-precipitation yields an amorphous Fe-S precursor. Black-Right-Pointing-Pointer The amorphous precursor solvothermally crystallizes to form metastable mackinawite. Black-Right-Pointing-Pointer Mackinawite-type FeS forms as single crystal colloidal nanosheets. Black-Right-Pointing-Pointer Samples are ferromagnetic with no evidence of superconductivity.

  10. Thin film pc-Si by aluminium induced crystallization on metallic substrate

    Directory of Open Access Journals (Sweden)

    Cayron C.

    2013-04-01

    Full Text Available Thin film polycrystalline silicon (pc-Si on flexible metallic substrates is promising for low cost production of photovoltaic solar cells. One of the attractive methods to produce pc-Si solar cells consists in thickening a large-grained seed layer by epitaxy. In this work, the deposited seed layer is made by aluminium induced crystallization (AIC of an amorphous silicon (a-Si thin film on metallic substrates (Ni/Fe alloy initially coated with a tantalum nitride (TaN conductive diffusion barrier layer. Effect of the thermal budget on the AIC grown pc-Si seed layer was investigated in order to optimize the process (i.e. the quality of the pc-Si thin film. Structural and optical characterizations were carried out using optical microscopy, μ-Raman and Electron Backscatter Diffraction (EBSD. At optimal thermal annealing conditions, the continuous AIC grown pc-Si thin film showed an average grain size around 15 μm. The grains were preferably (001 oriented which is favorable for its epitaxial thickening. This work proves the feasibility of the AIC method to grow large grains pc-Si seed layer on TaN coated metal substrates. These results are, in terms of grains size, the finest obtained by AIC on metallic substrates.

  11. Structural, optical and electronic properties of Fe doped ZnO thin films

    Science.gov (United States)

    Singh, Karmvir; Devi, Vanita; Dhar, Rakesh; Mohan, Devendra

    2015-09-01

    Fe doped ZnO thin films have been deposited by pulsed laser deposition technique on quartz substrate to study structural, optical and electronic structure using XRD, AFM, UV-visible and X-ray absorption spectroscopy. XRD study reveals that Fe doping has considerable effect on stress, strain, grain size and crystallinity of thin films. UV-visible study determines that band gap of pristine ZnO decreases with Fe doping, which can be directly correlated to transition tail width and grain size. Change in electronic structure with Fe doping has been examined by XAS study.

  12. Effect of Ti seed and spacer layers on structure and magnetic properties of FeNi thin films and FeNi-based multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Svalov, A.V., E-mail: andrey.svalov@ehu.es [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Department of Magnetism and Magnetic Nanomaterials, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Kurlyandskaya, G.V. [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Department of Magnetism and Magnetic Nanomaterials, Ural Federal University, 620002 Ekaterinburg (Russian Federation)

    2014-10-15

    Highlights: • Fe{sub 19}Ni{sub 81} films and FeNi-based multilayers were prepared by magnetron sputtering. • The samples were deposited onto glass substrates at room temperature. • Ti/FeNi films exhibit good (1 1 1) texture and crystallinity. • The thick Cu seed increases the coercive force of the magnetic layer. • The thin Ti spacer restores the magnetic softness of the Cu/Ti/FeNi multilayers. - Abstract: The microstructure and magnetic properties of sputtered permalloy films and FeNi-based multilayers prepared by magnetron sputtering have been studied. X-ray diffraction measurements indicate that Ti/FeNi films exhibit good (1 1 1) texture and crystallinity. Ti/FeNi bilayers with high crystallographic quality have relatively low resistivity. The Ti seed layer does not influence the magnetic properties of FeNi film in Ti/FeNi bilayers, but the thick Cu seed layer leads to an increase of the coercive force of the magnetic layer. For the FeNi films deposited on thick Cu seed layer, the (0 1 0) and (0 0 2) diffraction peaks of hcp nickel were clearly observed. The thin Ti spacer between Cu and FeNi layers prevents the formation of the nickel phase and restores the magnetic softness of the FeNi layer in the Cu/Ti/FeNi sample. Obtained results can be important for the development of multilayer sensitive elements for giant magnetoimpedance or magnetoresistance detectors.

  13. Solvothermal synthesis of Cu2Zn1-x Fe x SnS4 nanoparticles and the influence of annealing conditions on drop-casted thin films

    Science.gov (United States)

    Shadrokh, Zohreh; Yazdani, Ahmad; Eshghi, Hosein

    2016-04-01

    Cu2Zn1-x Fe x SnS4 (CZFTS) semiconductor alloy sphere-like nanoparticles were synthesized by a solvothermal method and their thin films were fabricated using a facile drop casting route then annealed in Ar and/or sulfur atmosphere. The sphere-like CZFTS nanoparticles demonstrate promising morphological, structural, and optical properties for an absorber layer in thin film solar cells. X-ray diffraction patterns, Raman spectra and EDS measurements of the samples indicate that a phase transition from kesterite to stannite occurred by increasing the Fe content to Fe/Fe + Zn = 0.61 ratio. Moreover, the increase in Fe content (0 ≤ x ≤ 1) resulted in a variation of the band gap energies of CZFTS from ˜1.515 to 1.206 eV on the basis of a parabolic decreasing trend. From a band gap bowing model we derived a small bowing constant of b ˜ 0.2009 ± 0.02 eV, indicating suitable miscibility of alloyed constituents in the host crystal lattice. The films annealed in sulfur showed a dense, uniform, low-crack surface, high thickness and low transmission compared to the films annealed in Ar flow. The four-point probe analysis showed an increasing resistivity of samples annealed in Ar with increasing Fe content.

  14. Study of nanocrystalline Fe-Al-N soft magnetic thin films

    Institute of Scientific and Technical Information of China (English)

    谢天; 郑代顺; 李晓红; 马云贵; 魏福林; 杨正

    2002-01-01

    Fe-Al-N films were fabricated by reactive sputtering using a radio-frequency magnetron sputtering system. Theeffects of Al and N content and annealing temperature on microstructure and magnetic properties were investigated.The Fe-Al-N films, which have good soft magnetic properties, consist of nanocrystalline α-Fe grains and a small amountof other phases in the boundaries of α-Fe grains. The average α-Fe grain size is about 10-15nm. A slight amount ofFeN and Al-N compounds precipitate in the boundaries of α-Fe grains and suppress their growth. Annealing improvesthe soft magnetic properties slightly by releasing the residual stress and reducing defects.

  15. Effect of Post Annealing on the Microstructure and Magnetic Properties of NdFeB/α-Fe/NdFeB Thin Films

    Institute of Scientific and Technical Information of China (English)

    Zhang Lina; Zhang Mingang; Yi Meiqing

    2007-01-01

    A series of nanocomposite thin films, composed of Nd2Fe14B and α-Fe, has been prepared by DC-magnetron sputtering combined ion beam sputtering onto Si (100) substrates. The effects of post annealing on the microstructure and magnetic properties of [NdFeB/α-Fe/NdFeB]-type thin films have been investigated. The X-ray diffraction (XRD) study showed that annealing of the films for 30min at temperatures 550,600,650,700℃ resulted in the appearance of diffraction peaks, characteristic for Nd2Fe14B tetragonal structure, α-Fe and Nd2O3 phases. The investigation using the Vibrating Sample Magnetometer (VSM) with a maximum applied field of 2 T indicated that with the increase of the annealing temperature, the magnetic properties of the multilayer films were improved and reached peak value at 650℃ (Hci=41.72kA·m-1, Mr/Ms=0.4, (BH)max=30.35kJ·m-3), after which the magnetic properties were decreased greatly. Along with the increase of the thickness of α-Fe layer from Tα-Fe16nm, the coercivity Hci, saturation magnetization Ms, and remanence ratio Mr/Ms all declined. As the Atomic Force Microscope (AFM) indicated, after being annealed at 650℃ for 30min, the sample was showed fine surface morphology with grain size 60nm≤dα-Fe≤80nm and 100nm≤dNdFeB≤150nm.

  16. Activity of glucose oxidase immobilized onto Fe3+ attached hydroxypropyl methylcellulose films.

    Science.gov (United States)

    Sözügeçer, Sevgi; Bayramgil, Nursel Pekel

    2013-01-01

    Hydroxypropyl methylcellulose (HMPC) insoluble films were prepared by (60)Co-γ irradiation of 10% (w/w) aqueous solutions of hydroxypropyl methylcellulose. The adsorption of Fe(3+) onto HPMC films was studied in the range of pH 3.0-7.0. The effect of initial concentrations of Fe(3+) solutions on adsorption capacity was studied in the range of 100-1000 ppm. Maximum adsorption capacity was found as 250 mg Fe(3+)/g dry HPMC film at pH 5.0. The structure and the morphology of Fe(3+)-attached HPMC film were evaluated by using FTIR/ATR and SEM-EDX methods. Glucose oxidase (GOX) immobilization on both pristine HPMC and maximum Fe(3+)-attached HPMC film was investigated in aqueous solutions containing different amount of GOX and at different pHs. Maximum GOX adsorption capacity was found as 500 mg/g Fe(3+)-attached HPMC film. Residual activity of GOX on pristine HPMC and Fe(3+)-attached HPMC films was investigated with changing pH. While maximum residual GOX activity was observed at pH 6.0 for free enzyme, it was obtained by HPMC and Fe(3+)-attached HPMC at pH 7.0. GOX desorption studies were achieved by using pH 6.0 buffer (I=0.02 M) and 0.1 M EDTA solutions. The long-term stability and activity studies of GOX, which is immobilized onto Fe(3+)-attached HPMC films are still under our investigation.

  17. Magnetic properties and microstructure of FePt/MoC/CrRu films

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Jai-Lin, E-mail: tsaijl@dragon.nchu.edu.tw; Luo, Qi-Shao; Chen, Po-Ran; Tseng, Yun-Ting

    2015-05-15

    The FePt films with thickness of 4−10 nm were deposited on MoC/CrRu/glass at substrate temperature ranged from 260 to 410 °C by using magnetron sputtering and strong (001) textured FePt films were obtained at 380 °C and 410 °C. The multi-functional MoC conductive intermediate layer was used to resist the Cr diffusion and promote the epitaxial growth of the (001) textured FePt film which shows perpendicular magnetization and a linear-like in-plane magnetic loop. The out-of plane coercivity and shape of demagnetization curve were dominated by the ordering degree and perpendicular magnetic anisotropy which were increased with deposited temperature. The FePt film deposited at 290 °C shows continuous morphology and change to interconnected structure at 350 °C and finally form the island like structure at 380 °C and 410 °C. Each island contains many FePt grains and the smaller grains size was 12.2 nm which obtained at 5 nm thick FePt film. Perpendicular anisotropy of 1.1×10{sup 7} erg/cm{sup 3} and coercivity of 8.2 kOe have been demonstrated in 7 nm thick FePt film. - Highlights: • The MoC conductive intermediate layer was resisted the Cr diffusion. • The MoC layer promote the epitaxial growth of (001) textured FePt film. • The FePt film shows perpendicular magnetization on MoC layer.

  18. 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.

  19. High-frequency magnetic characteristics of Fe-Co-based nanocrystalline alloy films

    Institute of Scientific and Technical Information of China (English)

    HIHARA; Takehiko; SUMIYAMA; Kenji

    2010-01-01

    Magnetically soft Fe-Co-based nanocrystalline alloy films were produced by two preparation methods:One using a new energetic cluster deposition technique and another using a conventional magnetron sputtering technique.Their structural,static magnetic properties and high-frequency magnetic characteristics were investigated.In the energetic cluster deposition method,by applying a high-bias voltage to a substrate,positively charged clusters in a cluster beam were accelerated electrically and deposited onto a negatively biased substrate together with neutral clusters from the same cluster source,to form a high-density Fe-Co alloy cluster-assembled film with good high-frequency magnetic characteristics.In the conventional magnetron sputtering method,only by rotating substrate holder and without applying a static inducing magnetic field on the substrates,we produced Fe-Co-based nanocrystalline alloy films with a remarkable in-plane uniaxial magnetic anisotropy and a good soft magnetic property.The obtained Fe-Co-O,Fe-Co-Ti-N,and Fe-Co-Cr-N films all revealed a high real permeability exceeding 500 at a frequency up to 1.2 GHz.This makes Fe-Co-based nanocrystalline alloy films potential candidates as soft magnetic thin film materials for the high-frequency applications.

  20. Fracture of Fe-3wt.% Si single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Prahl, J. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Machova, A. [Institute of Thermomechanics, Academy of Sciences of the Czech Republic, Dolejskova 5, 182 00 Prague 8 (Czech Republic); Landa, M. [Institute of Thermomechanics, Academy of Sciences of the Czech Republic, Dolejskova 5, 182 00 Prague 8 (Czech Republic); Hausild, P. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic)], E-mail: Petr.Hausild@fjfi.cvut.cz; Karlik, M. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Spielmannova, A. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Clavel, M. [Ecole Centrale Paris, LMSS-Mat, CNRS UMR 8579, Grande Voie des Vignes, 92295 Chatenay-Malabry (France); Haghi-Ashtiani, P. [Ecole Centrale Paris, LMSS-Mat, CNRS UMR 8579, Grande Voie des Vignes, 92295 Chatenay-Malabry (France)

    2007-07-25

    The ductile to brittle transition in {alpha}-iron was studied on four oriented single crystals of a Fe-3wt.% Si alloy using tensile tests of flat-notched specimens, scanning and transmission electron microscopy. The experimental results are compared with molecular dynamic simulations. Single-edge notched specimens were loaded in tension at room temperature, the crack propagated in a (001) plane and in the [1-bar10] direction. The crosshead speed was changed in the range from 0.1 to 5.0mm/min. Under the lowest loading rate, a plastic zone was formed at the notch tip, faster loading lead to brittle fracture. Fractographic analysis of one specimen ruptured at 1mm/min loading showed flat cleavage facets and tongues formed by the interaction of the principal crack with deformation twins. Besides the tongues, the fracture surface of the second sample ruptured at the same loading rate exhibited signs of plastic deformation. In the first specimen, transmission electron microscopy in the vicinity of the fracture surface confirmed deformation twinning and a very low dislocation density. In the second specimen, deformation twinning was assisted by slip of dislocations in the <111> {l_brace}112{r_brace} slip system. Molecular dynamics simulations confirmed that the crack growth has a more brittle character with increasing loading rates. At a slower loading rate, the crack growth is more difficult since it is impeded by emission of shielding dislocations from the crack tip in the <111> {l_brace}112{r_brace} slip system. Twin formation at the crack front was detected in simulations with edge cracks.

  1. Optical Properties of Mg, Fe, Co-Doped Near-Stoichiometric LiTaO3 Single Crystals

    Directory of Open Access Journals (Sweden)

    Chung Wen Lan

    2012-01-01

    Full Text Available Mg, Fe co-doped near-stoichiometric lithium tantalite (SLT single crystals were grown by employing the zone-leveling Czochralski (ZLCz technique. The optical properties, holographic parameters, as well as the composition of the grown crystals were measured. It was found that the Li/Ta ratio decreased with the doping of Mg and Fe ions. A red shift was observed in absorption spectrum for the Mg, Fe co-doped crystals compared to the undoped and Mg-doped ones. The effect of the iron ions (Fe2+ and Fe3+ was further discussed based on the specified absorption bands. Moreover, the occupation mechanism for the defects was discussed by using the IR absorption spectrum, which was attributed to the FeTa3− defects in the highly Fe-doped crystal. In addition, the holographic parameters were also found to be improved with a higher Fe/Ta ratio in the crystals.

  2. Thickness Dependence of Magnetic Properties in DyFeCo Films

    Institute of Scientific and Technical Information of China (English)

    Xiong Rui; Liu Hai-lin; Mei Xue-fei; Li Zuo-yi; Yang Xiao-fei; Shi Jing

    2004-01-01

    Films of amorphous DyFeCo were deposited on glass substrates using RF sputtering deposition system. The thickness dependence of the coercivity of DyFeCo films prepared under the same sputtering conditions was investigated. It is found that the composition is nearly thickness independent, while the coercivity is shown to increase with the film thickness increasing at the beginning, then above a certain thickness decrease with the thickness increasing. The thickness dependence of the coercivity is believed to be due to microstructure-induced variations in the short-range order during the film growth.

  3. Induced effects of Cu underlayer on (111) orientation of Fe50 Mn50 thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; WANG Feng-ping; LIU Huan-ping; WU Ping; QIU Hong; PAN Li-qing

    2005-01-01

    Effects of Cu underlayer on the structure of Fe50 Mn50 films were studied. Samples with a structure of Fe50 Mn50 (200 nm)/Cu(tCu) were prepared by magnetron sputtering on thermally oxidized silicon substrates at room temperature. The thickness of Cu underlayer varied from 0 to 60 nm in the intervals of 10 nm. High-vacuum annealing treatments, at different temperatures of 200, 300 and 400 ℃ for 1 h, respectively, on the Fe50 Mn50 (200 nm)/Cu(20 nm) thin films were performed. The surface morphologies and textures of the samples were measured by field emission scan electronic microscope (FE-SEM) and X-ray diffraction(XRD). Energy dispersive X-ray spectroscopy (EDX) and Auger electron spectroscopy(AES) were used to analyze the compositional distribution. It is found that Cu underlayer has an obvious induce effect on (111) orientation of Fe50 Mn50 thin films. The induce effects of Cu on (111) orientation of Fe50 Mn50 changed with the increase of Cu layer thickness and the best effect was obtained at the Cu layer thickness of 20 nm. High-vacuum annealing treatments cause the migration of Mn atoms towards surface of the film and interface between Cu layer and substrate. With the increasing annealing temperature, migration of Mn atoms is more obvious, which leads to a Fe-riched Fe-Mn alloy film.

  4. Coverage Effects on the Magnetism of Fe/MgO(001) Ultrathin Films

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Boubeta, C.

    2004-11-04

    Different aspects of the structure-magnetism and morphology-magnetism correlation in the ultrathin limit are studied in epitaxial Fe films grown on MgO(001). In the initial stages of growth the presence of substrate steps, intrinsically higher than an Fe atomic layer, prevent connection between Fe islands and hence the formation of large volume magnetic regions. This is proposed as an explanation to the superparamagnetic nature of ultrathin Fe films grown on MgO in addition to the usually considered islanded, or Vollmer-Weber, growth. Using this model, we explain the observed transition from superparamagnetism to ferromagnetism for Fe coverages above 3 monolayers (ML). However, even though ferromagnetism and magnetocrystalline anisotropy are observed for 4ML, complete coverage of the MgO substrate by the Fe ultrathin films only occurs around 6 ML as determined by polar Kerr spectra and simulations that consider different coverage situations. In annealed 3.5 ML Fe films, shape or configurational anisotropy dominates the intrinsic magnetocrystalline anisotropy, due to an annealing induced continuous to islanded morphological transition. A small interface anisotropy in thicker films is observed, probably due to dislocations observed at the Fe/MgO(001) interface.

  5. GIANT MAGNETO-IMPEDANCE OF PATTERNED FeSiB/Cu/FeSiB TRI-LAYER FILMS

    Institute of Scientific and Technical Information of China (English)

    X.H. Mao; Y. Zhou; M.S. Wu; B.C. Cai

    2003-01-01

    Sensitive magnetic field sensor with good performances can be fabricated utilizing the giant magneto-impedance (GMI) effect of soft magnetic multi-layer thin films. The transverse and longitudinal GMI effect in patterned FeSiB/Cu/FeSiB tri-layer films with the change of external magnetic field and frequency were studied at the same time. The change of the impedance of the films with the external magnetic fieldand frequency was shown. Comparing the longitudinal and transverse effect, the transverse effect has a larger linear range from zero magnetic field to a quite large magnetic field at all frequencies, and the change still were not saturated until the external magnetic field reached 1.2×104A/m, which illustrated that the films can be utilized to detect larger magnetic fields than now presented GMI sensors.

  6. Investigation of the magnetic properties in thin Fe50Pt50-xRhx films by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fenske, J.; Lott, D.; Schreyer, A. [GKSS Research Centre (Germany); Mankey, G.J. [University of Alabama, MINT Center (United States); Schmidt, W.; Schmalzl, K. [Juelich Research Centre (Germany); Tartakowskaya, E. [Institute for Magnetism, National Accademy of Science (United States)

    2009-07-01

    FePt-based alloys are typically the material of choice for magnetic information storage media. The high magnetic moment of Fe gives a large magnetization and the large atomic number of Pt results in a high magnetic anisotropy. This combination enables the written bits to be smaller than ever before, since magnetic grains with a high magnetic anisotropy are more thermally stable. One way to control the magnetic properties in these materials is through the introduction of a third element into the crystal matrix, e.g. Rh. When Rh is added to replace Pt in the equiatomic alloy, new magnetic phases emerge. Bulk samples of Fe{sub 50}Pt{sub 40}Rh{sub 10} for example, studied by magnetization measurements refer to an antiferromagnetic (AF)/ferromagnetic (FM) phase transition at about 150 K when heated. Additional magnetostriction measurements indicate that the phase transition could also be induced by applying a magnetic field. Here we present results on several Fe{sub 50}Pt{sub 50-x}Rh{sub x} films. These films were examined by neutron diffraction in dependence of temperature and magnetic field. The observed magnetic behaviours differ significant from the behaviour of the bulk system.

  7. Crystal structure and Mössbauer studies of the isotypic Fe6-cluster compounds RE15[Fe8C25], RE=Dy, Ho

    KAUST Repository

    Davaasuren, Bambar

    2015-05-01

    The carboferrates RE15[Fe8C25] (RE=Dy, Ho) were prepared from mixtures of the elements by arc-melting followed with subsequent annealing at 1373 K. The crystal structures were determined from single crystal X-ray diffraction data and revealed an isotypic relationship to Er15[Fe8C25] (hP48, P321). The main feature of the crystal structure is given by Fe6 cluster units characterized by covalent Fe-Fe bonding interactions. 57Fe Mössbauer spectra of Dy15[Fe8C25] were fitted by three subspectra with relative spectral weights of about 3:3:2 which is in general agreement with the crystal structure. Below 50 K, an onset of magnetic hyperfine fields at the three iron sites is observed which is supposed to be caused by dipolar fields arising from neighboring, slowly relaxing Dy magnetic moments.

  8. Crystal field effects on interionic distance in cubic MgO crystal doped with Fe{sup 2+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Ivascu, S.; Gruia, A.S. [Faculty of Physics, West University of Timisoara, Bd. V. Parvan 4, 300223-Timisoara (Romania); Avram, N.M., E-mail: avram@physics.uvt.ro [Faculty of Physics, West University of Timisoara, Bd. V. Parvan 4, 300223-Timisoara (Romania); Academy of Romanian Scientists, Independentei 54, 050094-Bucharest (Romania)

    2014-10-01

    The exchange charge model of crystal field was applied to determine the dependence of the crystal field strength 10Dq on interionic distances R between the Fe{sup 2+} impurity ion and O{sup 2−} ligands in cubic MgO:Fe{sup 2+}. The obtained results were extrapolated by the power law and was shown that 10Dq depends on R as 1/R{sup n}, with n=6.3486. The deviations of these values from the value n=5 (predicted by the simple point charge model of crystal field) is explained by the covalent and exchange effects between impurity ion and ligands; the contribution of these effects into the total crystal field strength was considered separately. The 10Dq functions obtained as a result of our calculations were used for estimations of the electron–vibrational constants, Huang–Rhys parameters, and Jahn–Teller stabilization energy, and compared with available literature data.

  9. Crystal field effects on interionic distance in cubic MgO crystal doped with Fe2+ ions

    Science.gov (United States)

    Ivascu, S.; Gruia, A. S.; Avram, N. M.

    2014-10-01

    The exchange charge model of crystal field was applied to determine the dependence of the crystal field strength 10Dq on interionic distances R between the Fe2+ impurity ion and O2- ligands in cubic MgO:Fe2+. The obtained results were extrapolated by the power law and was shown that 10Dq depends on R as 1/R, with n=6.3486. The deviations of these values from the value n=5 (predicted by the simple point charge model of crystal field) is explained by the covalent and exchange effects between impurity ion and ligands; the contribution of these effects into the total crystal field strength was considered separately. The 10Dq functions obtained as a result of our calculations were used for estimations of the electron-vibrational constants, Huang-Rhys parameters, and Jahn-Teller stabilization energy, and compared with available literature data.

  10. Microstructures of NiFe/nonmagnetic metal spacer/FeMn films and their influences on exchange coupling

    Institute of Scientific and Technical Information of China (English)

    LI; Minghua(李明华); YU; Guanghua(于广华); ZHU; Fengwu(朱逢吾); HE; Ke(何珂); LAI; Wuyan(赖武彦)

    2003-01-01

    Ta/NiFe/nonmagnetic metal spacer/FeMn films were prepared by magnetron sputtering. The dependences of the exchange coupling field (Hex) between an antiferromagnetic FeMn layer and a ferromagnetic NiFe layer on the thickness of nonmagnetic metal spacer layers were systematically studied. The results show that the Hex dramatically decreases with the increase in the thicknesses of Bi and Ag spacer layers. However, it gradually decreases with the increase in the thickness of a Cu spacer layer. For a Cu space layer, its crystalline structure is the same as that of NiFe and the lattice parameters of them are close to each other. The Cu layer and FeMn layer will epitaxially grow on the NiFe layer in succession, so the (111) texture of the FeMn layer will not be damaged. As a result, the Hex gradually decreases with the deposition thickness of a Cu layer. For an Ag space layer, its crystalline structure is the same as that of NiFe, but its lattice parameter is very different from that of NiFe. Thus, neither an Ag nor an FeMn layer will epitaxially grow on the NiFe layer and the (111) texture of the FeMn layer will be damaged. The Hex rapidly decreases with the increase in the deposition thickness of an Ag layer. For a Bi spacer layer, not only its crystalline structure but also its lattice parameter is greatly different from that of NiFe. For the same reason, the Bi and FeMn layer cannot epitaxially grow on the NiFe layer. The texture of the FeMn layer will also be damaged. Therefore, the Hex rapidly decreases with the increase in the deposition thickness of a Bi layer as well. However, the research result of X-ray photoelectron spectroscopy indicates that a very small amount of surfactant Bi atoms will migrate to the FeMn layer surface when they are deposited on the NiFe/FeMn interface. Thus, the Hex will hardly decrease.

  11. Thickness dependent activity of nanostructured TiO{sub 2}/{alpha}-Fe{sub 2}O{sub 3} photocatalyst thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akhavan, O., E-mail: oakhavan@sharif.edu [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Azadi Ave., Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of)

    2010-12-15

    The effect of thickness of TiO{sub 2} coating on synergistic photocatalytic activity of TiO{sub 2} (anatase)/{alpha}-Fe{sub 2}O{sub 3}/glass thin films as photocatalysts for degradation of Escherichia coli bacteria in a low-concentration H{sub 2}O{sub 2} solution and under visible light irradiation was investigated. Nanograined {alpha}-Fe{sub 2}O{sub 3} films with optical band-gap of 2.06 eV were fabricated by post-annealing of thermal evaporated iron oxide thin films at 400 deg. C in air. Increase in thickness of the Fe{sub 2}O{sub 3} thin film (here, up to 200 nm) resulted in a slight reduction of the optical band-gap energy and an increase in the photoinactivation of the bacteria. Sol-gel TiO{sub 2} coatings were deposited on the {alpha}-Fe{sub 2}O{sub 3} (200 nm)/glass films, and then, they were annealed at 400 deg. C in air for crystallization of the TiO{sub 2} and formation of TiO{sub 2}/Fe{sub 2}O{sub 3} heterojunction. For the TiO{sub 2} coatings with thicknesses {<=}50 nm, the antibacterial activity of the TiO{sub 2}/{alpha}-Fe{sub 2}O{sub 3} (200 nm) was found to be better than the activity of the bare {alpha}-Fe{sub 2}O{sub 3} film. The optimum thickness of the TiO{sub 2} coating was found to be 10 nm, resulting in about 70 and 250% improvement in visible light photo-induced antibacterial activity of the TiO{sub 2}/{alpha}-Fe{sub 2}O{sub 3} thin film as compared to the corresponding activity of the bare {alpha}-Fe{sub 2}O{sub 3} and TiO{sub 2} thin films, respectively. The improvement in the photoinactivation of bacteria on surface of TiO{sub 2}/{alpha}-Fe{sub 2}O{sub 3} was assigned to formation of Ti-O-Fe bond at the interface.

  12. Impact of thickness on microscopic and macroscopic properties of Fe-Te-Se superconductor thin films

    Directory of Open Access Journals (Sweden)

    N. Zhang

    2015-04-01

    Full Text Available A series of iron based Fe-Te-Se superconductor thin films depositing on 0.7wt% Nb-doped SrTiO3 at substrate temperatures in the 250°C -450°C range by pulsed laser ablation of a constituents well defined precursor FeTe0.55Se0.55 target sample. We study the possible growth mechanism and its influence on the superconductor properties. Experimental results indicate the superconductive and non-superconductive properties are modulated only by the thickness of the thin films through the temperature range. The films appear as superconductor whenever the thickness is above a critical value ∼30nm and comes to be non-superconductor below this value. Relative ratios of Fe to (Te+Se in the films retained Fe/(Te+Se1 for non-superconductor no matter what the film growth temperature was. The effect of film growth temperature takes only the role of modulating the ratio of Te/Se and improving crystallinity of the systems. According to the experimental results we propose a sandglass film growth mechanism in which the interfacial effect evokes to form a Fe rich area at the interface and Se or Te starts off a consecutive filling up process of chalcogenide elements defect sides, the process is significant before the film thickness reaches at ∼30nm.

  13. Giant magnetoimpedance effect in Fe75.5Cu1Nb3Si13.5B7 ribbon/FeGa film composite

    Science.gov (United States)

    Zhang, Yi; Gan, Tao; Wang, Tao; Wang, Feifei; Shi, Wangzhou

    2016-11-01

    Optimized giant magnetoimpedance effect of Fe75.5Cu1Nb3Si13.5B7 amorphous ribbon/Fe80Ga20 film composites has been investigated. FeCuNbSiB amorphous ribbons as the substrates are commercially available, magnetostrictive FeGa films are deposited on one or both sides of the ribbons by ion-beam sputtering. Compared with the GMI curves without FeGa layer, the GMI effect of FeCuNbSiB amorphous ribbon has been obviously improved with FeGa film covered (from 4% to 16%). Moreover, the details exhibit an interesting phenomenon: at a certain frequency, when the FeGa film covered on one side of the ribbon, the GMI ratio decreases with the thickness of the FeGa film; however, when the FeGa films covered on both sides of the ribbon, the GMI ratio increases with the thickness of the FeGa film. We mainly attribute the reason to strain-induced anisotropy, which is induced by magnetostrictive effect under a longitudinal applied magnetic field.

  14. Thermodynamics around the first-order ferromagnetic phase transition of Fe2P single crystals

    NARCIS (Netherlands)

    Hudl, M.; Campanini, D.; Caron, L.; Höglin, V.; Sahlberg, M.; Nordblad, P.; Rydh, A.

    2014-01-01

    The specific heat and thermodynamics of Fe2P single crystals around the first-order paramagnetic to ferromagnetic (FM) phase transition at TC≃217K are empirically investigated. The magnitude and direction of the magnetic field relative to the crystal axes govern the derived H−T phase diagram. Striki

  15. Metal-semiconductor transition materials. FeS and VO{sub 2} thin films by RF reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Fu Ganhua

    2007-06-15

    In the present work, two MST systems, FeS and VO{sub 2} thin films were investigated. Iron sulfide thin films over a range of composition were prepared by reactive sputtering. The influence of the substrate, sputter power, substrate temperature and stoichiometry on the structure and MST of iron sulfide films was investigated. Iron sulfide films deposited at different temperatures show temperature dependent structure and MST. FeS films on float glass show (110) and (112) orientations when the substrate temperature is 200 and 500 C, respectively. The transition temperature and width of the hysteresis loop determined from the temperature dependent conductivity curves of iron sulfide films decrease with the substrate temperature. Fe and S excess in FeS films both result in the decrease of the transition temperature and width of the hysteresis loop. The vacuum-annealing affects the MST of FeS films significantly. When FeS films were annealed below the deposition temperature, the transition temperature decreases; otherwise increases. The residual stress plays an important role during the annealing process. The higher the residual stress inside the FeS films is, the higher the transition temperature of FeS films. With the increase of the annealing temperature, the residual stress in FeS films is first released and then enhances, which gives rise first to the decrease and then increase of the transition temperature of FeS films. At high substrate temperatures, the residual stress is higher. In addition, the MST of FeS films was influenced by the ambient aging. With the increase of the aging time, the transition temperature first increases and then decreases. FeS films with different thicknesses were prepared. The correlation between the film thickness (grain size) and the MST switching characteristics of FeS films was established. With the decrease of the grain size, the density of grain boundaries increases, causing the increase of the conductivity of the semiconducting

  16. Anomalous Hall effect in a ferromagnetic Fe3Sn2 single crystal with a geometrically frustrated Fe bilayer kagome lattice

    Science.gov (United States)

    Wang, Qi; Sun, Shanshan; Zhang, Xiao; Pang, Fei; Lei, Hechang

    2016-08-01

    The anomalous Hall effect (AHE) is investigated for a ferromagnetic Fe3Sn2 single crystal with a geometrically frustrated kagome bilayer of Fe. The scaling behavior between anomalous Hall resistivity ρxy A and longitudinal resistivity ρx x is quadratic and further analysis implies that the AHE in the Fe3Sn2 single crystal should be dominated by the intrinsic Karplus-Luttinger mechanism rather than extrinsic skew-scattering or side-jump mechanisms. Moreover, there is a sudden jump of anomalous Hall conductivity σxy A appearing at about 100 K where the spin-reorientation transition from the c axis to the a b plane is completed. This change of σxy A might be related to the evolution of the Fermi surface induced by the spin-reorientation transition.

  17. SYNTHESIS AND CRYSTAL STRUCTURE OF A NEW Fe(II α-DIOXIMATE WITH TRIAZINE

    Directory of Open Access Journals (Sweden)

    О. Ciobanica

    2013-06-01

    Full Text Available The interaction of [Fe(DfgH2Py2] (where DfgH=monodeprotonated diphenylglyioxime, Py-pyridune and 1,3,5-triazine (Trz in chloroform resulted in a new coordination compound with the composition [Fe(DfgH2(Trz2]·2CHCl3 (1. The crystal structure of 1, determined by single crystal X-ray diffraction, revealed that Fe(II atom is coordinated by four oximic nitrogen atoms of two DfgH and two nitrogen atoms of two Trz ligands resulting in octahedral surrounding.

  18. Structural transformation of FePt nanocomposite films during annealing and its effects on magnetic properties

    Institute of Scientific and Technical Information of China (English)

    ZHAN Xiaoyuan; ZHANG Yue; GU Yousong; LI Jianmin

    2006-01-01

    Fe100-xPtx(x=30at.%-60at.% ) nanocomposite films were deposited on natural-oxidized Si(100) substrates by magnetron sputtering. The as-deposited films were annealed between 373 and 1073 K. In situ X-ray diffraction shows that the FePt nanocomposite films undergo a phase transformation from a disordered FCC phase to an ordered L10 phase between 673 and 773 K. The coercivity is 306 kA·m-1 whiles the average grain sizes is about 10 nm in the optimized FePt alloy film sample annealed at 673K. The adjustable coercivity and fine grain size suggest that this FePt nanocomposites system is suitable as recording media at extremely high areal density.

  19. Structural and magnetic properties of FeNi thin films fabricated on amorphous substrates

    Energy Technology Data Exchange (ETDEWEB)

    Tashiro, T. Y.; Mizuguchi, M., E-mail: mizuguchi@imr.tohoku.ac.jp; Kojima, T.; Takanashi, K. [Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577 (Japan); Koganezawa, T.; Kotsugi, M.; Ohtsuki, T. [Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Sayo, Hyogo 679-5198 (Japan)

    2015-05-07

    FeNi films were fabricated by sputtering and rapid thermal annealing on thermally amorphous substrates to realize the formation of an L1{sub 0}-FeNi phase by a simple method. Structural and magnetic properties of FeNi films were investigated by varying the annealing temperature. L1{sub 0}-FeNi superlattice peaks were not observed in X-ray diffraction patterns, indicating no formation of L1{sub 0}-ordered phase, however, the surface structure systematically changed with the annealing temperature. Magnetization curves also revealed a drastic change depending on the annealing temperature, which indicates the close relation between the morphology and magnetic properties of FeNi films fabricated on amorphous substrates.

  20. Electrical transport properties in Fe-Cr nanocluster-assembled granular films

    Science.gov (United States)

    Wang, Xiong-Zhi; Wang, Lai-Sen; Zhang, Qin-Fu; Liu, Xiang; Xie, Jia; Su, A.-Mei; Zheng, Hong-Fei; Peng, Dong-Liang

    2017-09-01

    The Fe100-xCrx nanocluster-assembled granular films with Cr atomic fraction (x) ranging from 0 to 100 were fabricated by using a plasma-gas-condensation cluster deposition system. The TEM characterization revealed that the uniform Fe clusters were coated with a Cr layer to form a Fe-Cr core-shell structure. Then, the as-prepared Fe100-xCrx nanoclusters were randomly assembled into a granular film in vacuum environments with increasing the deposition time. Because of the competition between interfacial resistance and shunting effect of Cr layer, the room temperature resistivity of the Fe100-xCrx nanocluster-assembled granular films first increased and then decreased with increasing the Cr atomic fraction (x), and revealed a maximum of 2 × 104 μΩ cm at x = 26 at.%. The temperature-dependent longitudinal resistivity (ρxx), magnetoresistance (MR) effect and anomalous Hall effect (AHE) of these Fe100-xCrx nanocluster-assembled granular films were also studied systematically. As the x increased from 0 to 100, the ρxx of all samples firstly decreased and then increased with increasing the measuring temperature. The dependence of ρxx on temperature could be well addressed by a mechanism incorporated for the fluctuation-induced-tunneling (FIT) conduction process and temperature-dependent scattering effect. It was found that the anomalous Hall effect (AHE) had no legible scaling relation in Fe100-xCrx nanocluster-assembled granular films. However, after deducting the contribution of tunneling effect, the scaling relation was unambiguous. Additionally, the Fe100-xCrx nanocluster-assembled granular films revealed a small negative magnetoresistance (MR), which decreased with the increase of x. The detailed physical mechanism of the electrical transport properties in these Fe100-xCrx nanocluster-assembled granular films was also studied.

  1. Truncated tetrahedron seed crystals initiating stereoaligned growth of FeSi nanowires.

    Science.gov (United States)

    Kim, Si-in; Yoon, Hana; Seo, Kwanyong; Yoo, Youngdong; Lee, Sungyul; Kim, Bongsoo

    2012-10-23

    We have synthesized epitaxially grown freestanding FeSi nanowires (NWs) on an m-Al(2)O(3) substrate by using a catalyst-free chemical vapor transport method. FeSi NW growth is initiated from FeSi nanocrystals, formed on a substrate in a characteristic shape with a specific orientation. Cross-section TEM analysis of seed crystals reveals the crystallographic structure and hidden geometry of the seeds. Close correlation of geometrical shapes and orientations of the observed nanocrystals with those of as-grown NWs indicates that directional growth of NWs is initiated from the epitaxially formed seed crystals. The diameter of NWs can be controlled by adjusting the composition of Si in a Si/C mixture. The epitaxial growth method for FeSi NWs via seed crystals could be employed to heteroepitaxial growth of other compound NWs.

  2. Direct observation of microstructures on superconducting single crystals of K x Fe2- y Se2

    Science.gov (United States)

    Tanaka, Masashi; Takeya, Hiroyuki; Takano, Yoshihiko

    2017-02-01

    Potassium-intercalated FeSe has been reported as a superconductor with a superconducting transition temperature (T c) of 30-48 K. However, the relationship among the surface morphology, compositional ratio, and crystal structure has not yet been clarified. This report directly reveals the correspondence among these three characteristics in single crystals with a T c onset of around 44 K by using a microsampling technique. Island-like parts on the surface of the crystals clearly exhibit the K x Fe2Se2 structure with perfect FeSe layers, which is formed in conjunction with the K2Fe4Se5 phase. This results in the appearance of the T c onset at 44 K.

  3. Tuning morphology and magnetism in epitaxial L10 -FePt films

    Science.gov (United States)

    Lupo, P.; Orna, J.; Casoli, F.; Nasi, L.; Ranzieri, P.; Calestani, D.; Algarabel, P.; Morellón, L.; Albertini, F.

    2013-01-01

    In this work, well-ordered epitaxial FePt thin films have been grown by RF sputtering on two different substrates (MgO (100) and SrTiO3 (100)) and the effect of different lattice parameters between the substrate and FePt film on morphology and magnetic behavior has been considered. Growth conditions have been optimized to obtain different morphologies and magnetic behaviors.

  4. Influence of inserted Mo layer on the thermal stability of perpendicularly magnetized Ta/Mo/Co20Fe60B20/MgO/Ta films

    Directory of Open Access Journals (Sweden)

    Minghua Li

    2016-04-01

    Full Text Available We studied the thermal stability of perpendicular magnetic anisotropy (PMA in Ta/Mo/CoFeB/MgO/Ta films with and without inserted Mo layers. In the absence of a Mo layer, the films show PMA at annealing temperatures below 300 °C. On the other hand, the insertion of a Mo layer preserves PMA at annealing temperatures of up to 500 °C; however, a higher annealing temperature leads to the collapse of PMA. X-ray photoelectron spectroscopy (XPS and high-resolution transmission electron microscopy (HRTEM were used to study the microstructure of the films to understand the deterioration of PMA. The XPS results show that the segregation of Ta is partly suppressed by inserting a Mo layer. Once inserted, Mo does not remain at the interface of Ta and CoFeB but migrates to the surface of the films. The HRTEM results show that the crystallization of the MgO (001 texture is improved owing to the higher annealing temperature of the Mo inserted sample. A smooth and clear CoFeB/MgO interface is evident. The inserted Mo layer not only helps to obtain sharper and smoother interfaces but also contributes to the crystallization after the higher annealing temperature of films.

  5. 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.

  6. High-frequency properties of discontinuous FeCoSi/native-oxide multilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Zuo Huaping [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Ge Shihui [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)], E-mail: gesh@lzu.edu.cn; Wang Zhenkun; Xiao Yuhua; Yao Dongsheng; Li Yanbo [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2009-10-15

    Discontinuous [FeCoSi (d)/native-oxide]{sub 50} multilayer films were fabricated by DC magnetron sputtering without any post-deposition treatment. The films exhibit good soft magnetic properties with initial permeability {mu}{sub i} larger than 100, the saturation magnetization 4{pi}M{sub s} and the in-plane uniaxial anisotropy field H{sub k} increase as the magnetic FeCoSi layer thickness d is increased from 5.5 to 20.5 A. As a consequence, the ferromagnetic resonance frequencies f{sub r} of the films increase from 2.0 to 3.9 GHz. The combination of high f{sub r} and large {mu}{sub i} makes these films potential candidates for magnetic devices applied in the high-frequency range. The origin of the excellent high-frequency properties in discontinuous FeCoSi/native-oxide multilayer films is discussed.

  7. Multiferroic BiFeO3 thin films for multifunctional devices.

    Science.gov (United States)

    Singh, Manish K; Yang, Yi; Takoudis, Christos G; Tatarenko, A; Srinivasan, G; Kharel, P; Lawes, G

    2010-09-01

    We report the metalorganic chemical vapor deposition of crystalline BiFeO3 films on platinized silicon substrates using n-butylferrocene, triphenylbismuth and oxygen. Based on thermogravimetric analysis data, the suitability of these two precursors for depositing BiFeO3 is discussed. The deposited films were characterized for structure and morphology using X-ray diffraction and scanning electron microscopy. Composition analysis using X-ray photoelectron spectroscopy revealed that the films were stoichiometric BiFeO3. Electrostatic force microscopy indicated that the film had polarizable domains that showed no deterioration in polarization over time long after electric poling. The film showed a saturation magnetization of 10 +/- 1 emu/cm3 at room temperature.

  8. Structure and magnetic properties of Ni/Cu/Fe/MgO(001) films.

    Science.gov (United States)

    Lauhoff, G; Vaz, C A F; Bland, J A C

    2009-04-15

    The structural and magnetic properties of thin Ni films grown on Cu/Fe/MgO(001) and Cu/MgO(001) buffer layers are investigated and compared to those grown on Cu/Si(001). The use of an Fe seed layer a few monolayers thick leads to the epitaxial growth of high surface quality Cu(001) buffer layers on MgO(001), while Cu growth on the bare MgO(001) substrate results in polycrystalline films. Magneto-optic Kerr effect magnetometry shows that Ni films grown on Cu/Fe/MgO(001) exhibit dominant perpendicular magnetic anisotropy up to ∼90 Å, which is similar to that of Ni films grown on Cu/Si(001). The polycrystalline Ni films also exhibit perpendicular magnetic remanence, but with a dominant in-plane magnetization component.

  9. Structure and magnetic properties of Ni/Cu/Fe/MgO(001) films

    Energy Technology Data Exchange (ETDEWEB)

    Lauhoff, G; Vaz, C A F; Bland, J A C [Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE (United Kingdom)], E-mail: georglauhoff@georglauhoff.com, E-mail: carlos.vaz@cantab.net

    2009-04-15

    The structural and magnetic properties of thin Ni films grown on Cu/Fe/MgO(001) and Cu/MgO(001) buffer layers are investigated and compared to those grown on Cu/Si(001). The use of an Fe seed layer a few monolayers thick leads to the epitaxial growth of high surface quality Cu(001) buffer layers on MgO(001), while Cu growth on the bare MgO(001) substrate results in polycrystalline films. Magneto-optic Kerr effect magnetometry shows that Ni films grown on Cu/Fe/MgO(001) exhibit dominant perpendicular magnetic anisotropy up to {approx}90 A, which is similar to that of Ni films grown on Cu/Si(001). The polycrystalline Ni films also exhibit perpendicular magnetic remanence, but with a dominant in-plane magnetization component.

  10. Influence of microstructure on the corrosion resistance of Fe-44Ni thin films

    Institute of Scientific and Technical Information of China (English)

    Lin Lu; Tian-cheng Liu; Xiao-gang Li

    2016-01-01

    An Fe–44Ni nanocrystalline (NC) alloy thin film was prepared through electrodeposition. The relation between the microstructure and corrosion behavior of the NC film was investigated using electrochemical methods and chemical analysis approaches. The results show that the NC film is composed of a face-centered cubic phase (γ-(Fe,Ni)) and a body-centered cubic phase (α-(Fe,Ni)) when it is annealed at temperatures less than 400°C. The corrosion resistance increases with the increase in grain size, and the corresponding corrosion process is controlled by oxygen reduction. The NC films annealed at 500°C and 600°C do not exhibit the same pattern, although their grain sizes are considerably large. This result is attributed to the existence of an anodic phase, Fe0.947Ni0.054, in these films. Under this condition, the related corrosion process is synthetically controlled by anodic dissolution and depolarization.

  11. 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.

  12. Structures and growth mechanisms of poly-(3-hydroxybutyrate) (PHB) crystallized from solution and thin melt film

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The spherulitic structures and morphologies of poly-(3-hydroxybutyrate) (PHB) crystallized from a so- lution and a thin melt film were investigated in this study. The formation mechanisms of banded spherulites under different crystallization conditions are proposed. It was found that the formation of banded spherulites was caused by the rhythmic crystal growth of the spherulites and lamellar twisting growth for the polymer crystallization from a thin melt film and a solution, respectively.

  13. Mesoporous multilayer thin films: environment-sensitive photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Soler Illia, Galo; Fuertes, Maria Cecilia; Angelome, Paula Cecilia [Comision Nacional de Energia Atomica, San Martin, Buenos Aires (Argentina). Centro Atomico Constituyentes. Gerencia de Quimica; Marchi, Maria Claudia [Universidad de Buenos Aires (Argentina). Facultad de Ciencias Exactas y Naturales. INQUIMAE; Troiani, Horacio [Comision Nacional de Energia Atomica (CNEA), San Carlos de Bariloche (Argentina). Centro Atomico Bariloche and Instituto Balseiro; Luca, Vittorio [Australian Nuclear Science and Technology Organization, Lucas Heights (Australia). Inst. of Materials and Engineering Sciences; Miguez, Hernan [Consejo Superior de Investigaciones Cientificas, Isla de La Cartuja, Sevilla (Spain). Inst. de Ciencia de Materiales

    2008-11-15

    Photonic Crystals made up of stacked mesoporous thin films (MTF) were produced by sequential deposition. These materials present order at different length scales: atomic (local structure), mesoscopic (ordered mesopores) and submicronic (controlled thickness), which were accurately assessed by Small Angle X-ray Scattering (2D SAXS, D11A SAXS1) and X-ray Reflectometry (XRR, D10A XRD2). Each MTF building block of a complex multilayer architecture behaves like an 'optical switch' in the presence of vapours. Its electronic density (and therefore the refractive index) changes due to capillary condensation of a given solvent within the pore systems. This allows for the creation of photonic crystals that are responsive to environment, with promising applications in selective sensing or active waveguides. (author)

  14. Physical and electrical characteristics of NiFe thin films using ultrasonic assisted pulse electrodeposition

    Science.gov (United States)

    Asa Deepthi, K.; Balachandran, R.; Ong, B. H.; Tan, K. B.; Wong, H. Y.; Yow, H. K.; Srimala, S.

    2016-01-01

    Nickel iron (NiFe) thin films were prepared on the copper substrate by ultrasonic assisted pulse electrodeposition under galvanostatic mode. Careful control of the thin films deposition is essential as the electrical properties of the films could be greatly affected, particularly if low quality films are produced. The preparation of NiFe/Cu thin films was aimed to reduce the grain size of NiFe particles, surface roughness and electrical resistivity of the copper substrates. Various parameters were systematically studied including current magnitude, deposition time and ultrasonic bath temperature. The optimized conditions to obtain NiFe permalloy, which subsequently applied to all investigated samples, were found at a current magnitude of 70 mA deposited for a duration of 2 min under ultrasonic bath temperature of 27 °C. The composition of NiFe permalloy was as close as Ni 80.71% and Fe 19.29% and the surface roughness was reduced from 12.76 nm to 2.25 nm. The films electrical resistivity was decreased nearly sevenfold from an initial value of 67.32 μΩ cm to 9.46 μΩ cm.

  15. Thin (111) oriented CoFe{sub 2}O{sub 4} and Co{sub 3}O{sub 4} films prepared by decomposition of layered cobaltates

    Energy Technology Data Exchange (ETDEWEB)

    Buršík, Josef, E-mail: bursik@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Soroka, Miroslav, E-mail: soroka@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Uhrecký, Róbert, E-mail: uhrecky@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Kužel, Radomír, E-mail: kuzel@karlov.mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Mika, Filip, E-mail: filip.mika@isibrno.cz [Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 147, 612 64 Brno (Czech Republic); Huber, Štěpán, E-mail: stepan.huber@vscht.cz [University of Chemistry and Technology, Faculty of Chemical Technology, Technická 5, 166 28 Prague 6 (Czech Republic)

    2016-07-15

    Graphical abstract: Pole figures of NaCoO{sub 2} (left) and of CoFe{sub 2}O{sub 4} (right) films formed through the transformation of O3-type NaCoO{sub 2} phase in consequence of sodium deintercalation occurring at 800 °C. Films were prepared by chemical solution deposition on MgO(111) substrate. - Highlights: • Epitaxial Na(CoFe)O{sub 2} thin films by means of chemical solution deposition were prepared. • Oriented spinel films through transformation of Na(CoFe)O{sub 2} were obtained. • Orientation relation to MgO, SrTiO{sub 3} and Zr(Y)O{sub 2} substrates were determined. • Structural aspects of Na(CoFe)O{sub 2} → CoFe{sub 2}O{sub 4} transformation pathway were elucidated. - Abstract: The formation and structural characterization of highly (111)-oriented Co{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4} films prepared by a novel procedure from 00l-oriented NaCoO{sub 2} and Na(CoFe)O{sub 2} is reported. The Na(CoFe)O{sub 2} films were deposited on MgO, SrTiO{sub 3}, LaAlO{sub 3}, and Zr(Y)O{sub 2} single crystals with (100) and (111) orientations by chemical solution deposition method and crystallized at 700 °C. Subsequently they were transformed into (111)-oriented spinel phase during post-growth annealing at 800–1000 °C. Morphology and structure of the films was investigated by means of scanning electron microscopy and X-ray diffraction. While all spinel films exhibit pronounced out-of-plane orientation irrespective of substrate, the rate of in-plane orientation strongly depend on lattice misfit values. Different epitaxial phenomena ranging from true one-to-one epitaxy to the existence of many-to-one epitaxy involving two or more orientations were determined by full 3D texture analysis.

  16. Effects of Ru and Ag cap layers on microstructure and magnetic properties of FePt ultrathin films.

    Science.gov (United States)

    Liu, Mingfeng; Jin, Tianli; Hao, Liang; Cao, Jiangwei; Wang, Ying; Wu, Dongping; Bai, Jianmin; Wei, Fulin

    2015-01-01

    The effects of Ru and Ag cap layers on the microstructure and magnetic properties of the FePt ultrathin films have been investigated. The results indicate that i) The Ag cap layer segregates from the FePt/Ag bilayer, lowers the FePt ordering temperature, promotes the FePt thin films to form island structure, and enhances the coercivity; ii) The Ru cap layer increases the FePt ordering temperature, helps to maintain smooth continuous structure film, and restrains the FePt (001) orientation and perpendicular magnetic anisotropy (PMA). The effects become more pronounced for the 3-nm-thick FePt thin films. The effects can be mainly attributed to the different melting point and thermal expansion stress between the cap layer and FePt thin films.

  17. Effects of Ru and Ag cap layers on microstructure and magnetic properties of FePt ultrathin films

    Science.gov (United States)

    Liu, Mingfeng; Jin, Tianli; Hao, Liang; Cao, Jiangwei; Wang, Ying; Wu, Dongping; Bai, Jianmin; Wei, Fulin

    2015-04-01

    The effects of Ru and Ag cap layers on the microstructure and magnetic properties of the FePt ultrathin films have been investigated. The results indicate that i) The Ag cap layer segregates from the FePt/Ag bilayer, lowers the FePt ordering temperature, promotes the FePt thin films to form island structure, and enhances the coercivity; ii) The Ru cap layer increases the FePt ordering temperature, helps to maintain smooth continuous structure film, and restrains the FePt (001) orientation and perpendicular magnetic anisotropy (PMA). The effects become more pronounced for the 3-nm-thick FePt thin films. The effects can be mainly attributed to the different melting point and thermal expansion stress between the cap layer and FePt thin films.

  18. A study on electrodeposited NiFe1− alloy films

    Indian Academy of Sciences (India)

    M Bedir; Ö F Bakkaloğlu; İ H Karahan; M Öztaş

    2006-06-01

    NiFe1− (0.22 ≤ ≤ 0.62) alloy films were grown by electrodeposition technique. A shift in diffraction peaks of NiFe and Ni3Fe was detected with increasing Ni content. The highest positive magnetoresistance ratio was detected as 5% in Ni0.51Fe0.49. Positive and negative anisotropic magnetoresistance were observed in longitudinal and transverse geometries respectively. The highest anisotropic magnetoresistance ratio of 9.8% was also detected in Ni0.51Fe0.49. The angular variation of magnetoresistance was studied. Magnetisation loop curves show that NiFe alloy films have a linear decreasing anisotropy constant with increasing Ni deposit content and show a decreasing behavior of coercivity which indicates soft magnetic property with increasing Ni deposit content.

  19. 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

  20. Influence of interstitial Fe to the phase diagram of Fe1+yTe1-xSex single crystals

    Science.gov (United States)

    Sun, Yue; Yamada, Tatsuhiro; Pyon, Sunseng; Tamegai, Tsuyoshi

    2016-08-01

    Superconductivity (SC) with the suppression of long-range antiferromagnetic (AFM) order is observed in the parent compounds of both iron-based and cuprate superconductors. The AFM wave vectors are bicollinear (π, 0) in the parent compound FeTe different from the collinear AFM order (π, π) in most iron pnictides. Study of the phase diagram of Fe1+yTe1-xSex is the most direct way to investigate the competition between bicollinear AFM and SC. However, presence of interstitial Fe affects both magnetism and SC of Fe1+yTe1-xSex, which hinders the establishment of the real phase diagram. Here, we report the comparison of doping-temperature (x-T) phase diagrams for Fe1+yTe1-xSex (0 ≤ x ≤ 0.43) single crystals before and after removing interstitial Fe. Without interstitial Fe, the AFM state survives only for x < 0.05, and bulk SC emerges from x = 0.05, and does not coexist with the AFM state. The previously reported spin glass state, and the coexistence of AFM and SC may be originated from the effect of the interstitial Fe. The phase diagram of Fe1+yTe1-xSex is found to be similar to the case of the “1111” system such as LaFeAsO1-xFx, and is different from that of the “122” system.

  1. Study of microstructure and magnetic properties of L10 FePt/SiO2 thin films

    Directory of Open Access Journals (Sweden)

    Giannopoulos G.

    2014-07-01

    Full Text Available Achieving magnetic recording densities in excess of 1Tbit/in2 requires not only perpendicular media with anisotropies larger than 7 MJ/m3, making FePt alloys an ideal choice, but also a narrow distribution below 10 nm for a reduced S/N ratio. Such grain size reduction and shape control are crucial parameters for high density magnetic recording, along with high thermal stability. Previous work has shown that the L10 FePt grain size can be controlled by alloying FePt with materials such as C, Ag, and insulators such as AlOx, MgO. Au and Al2O3 also act to segregate and magnetically decouple the FePt grains. Better results were obtained with C with respect to the uniformity of grains and SiO2 with respect to the shape. We present our results on co-sputtering FePt with C or SiO2 (up to 30 vol % on MgO (001 single crystal substrates at 350 and 500 oC. With C or SiO2 addition we achieved grain size reduction, shape control and isolated structure formation, producing continuous films with high uniformity and a narrow grain size distribution. These additions thus allow us to simultaneously control the coercivity and the S/N ratio. We also will report structural and microstructural properties.

  2. Crystallization kinetics of amorphous Nd3.6 Pr5.4 Fe83Co3B5 and preparation of α-Fe/Nd2Fe14B nanocomposite magnets by controlled melt-solidification technique

    Institute of Scientific and Technical Information of China (English)

    杨丽; 尚勇

    2003-01-01

    The crystallization kinetics of amorphous Nd3. 6 Pr5.4 Fe83 Co3 B5 and the preparation of α-Fe/Nd2 Fe14 B nanocomposite magnets by controlled melt-solidification of Nd3.6Pr5.4Fe83Co3B5 was investigated by employing DTA, XRD, and TEM. The results show that a metastable intermediate phase Nd8Fe27B24 prior to α-Fe and Nd2 Fe14 B phases is crystallized as the amorphous Nd3.6 Pr5.4 Fe83 Co3 B5 is heated to 1 223 K. The crystallization activation energy of α-Fe and Nd8 Fe27324 phases is larger at the beginning stage of crystallization, and then it decreases with crystallized fraction x for the former and has little change when x is below 70% for the latter, which essentially results in an α-Fe/Nd2 Fe14 B microstructure with a relatively coarse grain size about 20-60 nm and a non-uniform distribution of grain size in the annealed alloy. The a-Fe/Nd2 Fe14 B nanocomposite magnets with a small average grain size about 14 nm and a quite uniform grain size distribution were prepared by controlled melt-solidification of nealing the amorphous Nd3. 6 Pr5. 4 Fe83 Co3 B5 precursor alloy.

  3. Al-4(Cr, Fe): single crystal growth by the Czochralski method and structural investigation with neutrons at FRM II

    OpenAIRE

    Bauer, Birgitta; Pedersen, Bjoern; Gille, Peter

    2009-01-01

    A single crystal of Al-4(Cr,Fe) with composition Al78Cr19Fe3 grown bythe Czochralski method was studied by neutron diffraction for the firsttime. As a preliminary result the neutron diffraction experiment

  4. Charge defects and highly enhanced multiferroic properties in Mn and Cu co-doped BiFeO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Guohua; Tan, Guoqiang, E-mail: tan3114@163.com; Luo, Yangyang; Liu, Wenlong; Xia, Ao; Ren, Huijun

    2014-06-01

    Pure BiFeO{sub 3} (BFO) and Mn, Cu co-doped BiFeO{sub 3} (BFMCO) thin films were deposited on fluorine doped tin oxide (FTO) substrates by a chemical solution deposition method. Detailed investigations were made on the effects of Mn and Cu co-doping on the crystal structure, the defect chemistry, multiferroic properties of the BFO thin films. With the co-doping of Mn and Cu, a structural transition from the rhombohedral (R3c:H) to the biphasic structure (R3c:H + P1) is confirmed by XRD, Rietveld refinement and Raman analysis. X-ray photoelectron spectroscopy (XPS) analysis shows that the coexistence of Fe{sup 2+}/Fe{sup 3+} and Mn{sup 2+}/Mn{sup 3+} ions in the co-doping films are demonstrated. Meanwhile, the way of the co-doping at B-sits is conducive to suppress Fe valence state of volatility and to decrease oxygen vacancies and leakage current. It's worth noting that the co-doping can induce the superior ferroelectric properties (a huge remanent polarization, 2P{sub r} ∼ 220 μC/cm{sup 2} and a relatively low coercive field, 2E{sub c} ∼ 614 kV/cm). The introduction of Mn{sup 2+} and Cu{sup 2+} ions optimizes the magnetic properties of BFO thin films by the biphasic structure and the destruction of spin cycloid.

  5. Domain Selectivity in BiFeO3 Thin Films by Modified Substrate Termination

    NARCIS (Netherlands)

    Solmaz, Alim; Huijben, Mark; Koster, Gertjan; Egoavil, Ricardo; Gauquelin, Nicolas; Van Tendeloo, Gustaaf; Verbeeck, Jo; Noheda, Beatriz; Rijnders, Guus

    2016-01-01

    Ferroelectric domain formation is an essential feature in ferroelectric thin films. These domains and domain walls can be manipulated depending on the growth conditions. In rhombohedral BiFeO3 thin films, the ordering of the domains and the presence of specific types of domain walls play a crucial r

  6. Tuning the atomic and domain structure of epitaxial films of multiferroic BiFeO3

    NARCIS (Netherlands)

    Daumont, C. J. M.; Farokhipoor, S.; Ferri, A.; Wojdel, J. C.; Iniguez, Jorge; Kooi, B. J.; Noheda, Beatriz; Wojdeł, J.C.

    2010-01-01

    Recent works have shown that the domain walls of room-temperature multiferroic BiFeO3 (BFO) thin films can display distinct and promising functionalities. It is thus important to understand the mechanisms underlying domain formation in these films. High-resolution x-ray diffraction and piezoforce mi

  7. Bandgap determination of P(VDF–TrFE) copolymer film by electron energy loss spectroscopy

    Indian Academy of Sciences (India)

    Dipankar Mandal; K Henkel; K Müller; D Schmeißer

    2010-08-01

    The ferroelectric of poly(vinylidene fluoride trifluoroethylene), P(VDF–TrFE) is confirmed for 100 nm thickness spin coated copolymer film. The homogeneous coverage of the copolymer film is investigated by the help of X-ray photoelectron spectroscopy (XPS). Most importantly, the existing bandgap in the crystalline phase of the copolymer is determined directly from the electron energy loss spectroscopy (EELS).

  8. Praseodymium Cuprate Thin Film Cathodes for Intermediate Temperature Solid Oxide Fuel Cells: Roles of Doping, Orientation, and Crystal Structure.

    Science.gov (United States)

    Mukherjee, Kunal; Hayamizu, Yoshiaki; Kim, Chang Sub; Kolchina, Liudmila M; Mazo, Galina N; Istomin, Sergey Ya; Bishop, Sean R; Tuller, Harry L

    2016-12-21

    Highly textured thin films of undoped, Ce-doped, and Sr-doped Pr2CuO4 were synthesized on single crystal YSZ substrates using pulsed laser deposition to investigate their area-specific resistance (ASR) as cathodes in solid-oxide fuel cells (SOFCs). The effects of T' and T* crystal structures, donor and acceptor doping, and a-axis and c-axis orientation on ASR were systematically studied using electrochemical impedance spectroscopy on half cells. The addition of both Ce and Sr dopants resulted in improvements in ASR in c-axis oriented films, as did the T* crystal structure with the a-axis orientation. Pr1.6Sr0.4CuO4 is identified as a potential cathode material with nearly an order of magnitude faster oxygen reduction reaction kinetics at 600 °C compared to thin films of the commonly studied cathode material La0.6Sr0.4Co0.8Fe0.2O3-δ. Orientation control of the cuprate films on YSZ was achieved using seed layers, and the anisotropy in the ASR was found to be less than an order of magnitude. The rare-earth doped cuprate was found to be a versatile system for study of relationships between bulk properties and the oxygen reduction reaction, critical for improving SOFC performance.

  9. Direct observation and mechanism of increased emission sites in Fe-coated microcrystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Huang, Pin-Chang; Shih, Wen-Ching [Graduate Institute in Electro-Optical Engineering, Tatung University, Taipei 104, Taiwan (China); Chen, Huang-Chin; Lin, I-Nan [Department of Physics, Tamkang University, New-Taipei 251, Taiwan (China)

    2012-06-15

    The electron field emission (EFE) properties of microcrystalline diamond (MCD) films are significantly enhanced due to the Fe coating and post-annealing processes. The 900 Degree-Sign C post-annealed Fe coated diamond films exhibit the best EFE properties, with a turn on field (E{sub 0}) of 3.42 V/{mu}m and attain EFE current density (J{sub e}) of 170 {mu}A/cm{sup 2} at 7.5 V/{mu}m. Scanning tunnelling spectroscopy (STS) in current imaging tunnelling spectroscopy mode clearly shows the increased number density of emission sites in Fe-coated and post-annealed MCD films than the as-prepared ones. Emission is seen from the boundaries of the Fe (or Fe{sub 3}C) nanoparticles formed during the annealing process. In STS measurement, the normalized conductance (dI/dV/I/V) versus V curves indicate nearly metallic band gap, at the boundaries of Fe (or Fe{sub 3}C) nanoparticles. Microstructural analysis indicates that the mechanism for improved EFE properties is due to the formation of nanographite that surrounds the Fe (or Fe{sub 3}C) nanoparticles.

  10. Formation of particulate Fe-Al films by selective oxidation of aluminum

    Science.gov (United States)

    Jang, Pyungwoo; Shin, Seung Chan

    2013-09-01

    Fe-5wt%Al films were RF-sputtered and annealed in an atmosphere of hydrogen and water vapor mixture at 1173 K for up to 200 min in order to selectively oxidize aluminum. As the annealing time increased, the morphology of the films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. Thermodynamics simulation was performed to determine the ideal conditions for this process. Temperatures exceeding 1073 K are necessary to prevent iron from oxidation confirmed by both the depth profile in XPS and magnetic moment increment in VSM. Annealing the films in an atmosphere with a very low dew point of 77 K did not make the films become particulate. New findings are expected to be applied to the thin film inductors for GHz application as well as to manufacturing process of nanoparticles.

  11. Epitaxial growth of Fe/Ag single crystal superlattices and their magnetic properties

    Institute of Scientific and Technical Information of China (English)

    Yu Gu; Fei Zeng; Fang Lv; Yuli Cu; Pei-yong Yang; Feng Pan

    2009-01-01

    Single crystal Fe/Ag(001) superlattices with various periodicities were fabricated using ultrahigh vacuum evaporation de-position.It was found that single crystal bcc Fe layers and single crystal fcc Ag layers can epitaxially grow on a single crystal Ag buffer layer alternately,which was deposited on NaCl single crystal chips by ion beam assisted deposition.The magnetic measure-ments of the superlattices reveal an oscillation coupling between ferromagnetism and antiferromagnetism as a function of the Ag layer thickness.The oscillation period,which is 1 nm (5 Ag layers),is in good agreement with the calculated values when the Ag thickness is greater than 1.5 nm.While the thickness of the Ag spacer layer decreases to 1 nm,the oscillation coupling varies from calculations,which can be attributed to the intermixing of the interlayers according to the annealing results.

  12. Influence of dynamic crystallization on exchange-coupled NdFeB nanocrystalline permanent magnets

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ran; LIU Ying; MA Yilong; ZHANG Longfeng; XU Jianchuan; GAO Shengji

    2006-01-01

    Dynamic crystallization was introduced to improve the magnetic properties of NdFeB nanocrystalline permanent magnets by optimizing microstructure. The microstructure was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It has been determined that, compared with the conventional heat treatment, dynamic crystallization can shorten the crystallization time. Moreover, dynamic crystallization can refine grains, enhance the exchange-coupled interaction among grains, and promote the magnetic properties. As a result, the optimal magnetic properties of Nd10.5(FeCoZr)83.4B6.1(Br=0.685T, Hci =732 kA·m -1 , Hcb =429 kA·m-1 ,( BH )m=75 kJ·m -3 ) are obtained after dynamic crystallization heat treatment at 700 ℃ for 10 min.

  13. Modelling of primary bcc-Fe crystal growth in a Fe{sub 85}B{sub 15} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Palumbo, M. [Dip. Chimica I.F.M. and NIS, Universita di Torino, via Giuria 9, 10125 Turin (Italy); Baricco, M. [Dip. Chimica I.F.M. and NIS, Universita di Torino, via Giuria 9, 10125 Turin (Italy)]. E-mail: marcello.baricco@unito.it

    2005-05-15

    A kinetic modelling of primary crystallization in metallic glasses, based on the CALPHAD approach and the moving boundary model, has been applied to the Fe-B system. The DICTRA software has been used to perform numerical calculations. Kinetic and thermodynamic parameters (atomic mobilities and thermodynamic factors) are required and they have been obtained from the literature. Various simulations have been performed in order to evaluate the influence of different parameters choice. The soft impingement effect has been discussed. Furthermore, amorphous Fe{sub 85}B{sub 15} samples have been prepared and examined by differential scanning calorimetry. Calculated and experimental results, both on continuous heating and isothermal conditions, have been compared.

  14. Single step synthesis of (a-Fe2O3) hematite films by hydrothermal electrochemical deposition

    OpenAIRE

    2015-01-01

    A single step electrodeposition of alpha-Fe2O3 films under hydrothermal conditions without post-annealing requirement is described. Primary attention is paid to understand the effects of synthesis conditions, such as temperature, precursor concentration, pH, and time on the structure and morphology of the films. Moreover, the photoelectrochemical properties of hematite films grown by hydrothermal-electrochemical deposition (HED) are also discussed. It is discovered that HED enables the produc...

  15. Single step synthesis of (a-Fe2O3) hematite films by hydrothermal electrochemical deposition

    OpenAIRE

    Yılmaz, Ceren; Ünal, Uğur

    2015-01-01

    A single step electrodeposition of alpha-Fe2O3 films under hydrothermal conditions without post-annealing requirement is described. Primary attention is paid to understand the effects of synthesis conditions, such as temperature, precursor concentration, pH, and time on the structure and morphology of the films. Moreover, the photoelectrochemical properties of hematite films grown by hydrothermal-electrochemical deposition (HED) are also discussed. It is discovered that HED enables the produc...

  16. The Electrical Conductivity of the Three-layer Polycrystalline Films Co / Ag(Cu / Fe in the Conditions of Atoms Interdiffusion

    Directory of Open Access Journals (Sweden)

    V.B. Loboda

    2014-04-01

    Full Text Available The paper presents results of experimental studies of crystal structure and electrical resistivity in the three-layer Co / Ag / Fe and Co / Cu / Fe nanocrystalline films and. It has been shown that all the samples, annealed at 700 K with dCu,Ag > 5 nm, are three-phase (FCC-Co, FCC-Ag, FCC-Cu, respectively, and BCC-Fe. The dependence of the three-layer films resistivity on the layer thickness has been obtained experimentally. It has been detected that the above-mentioned dependence is nonmonotonic, which is conditioned by the diffuse nature of the interaction of electrons with interfaces of the conductor.

  17. Growth and Holographic Storage Properties of Sc, Fe Co-Doped Lithium Niobate Crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The holographic storage properties of Fe (0.03% (mass fraction) Fe2O3):LiNbO3 doped with Sc at different levels (0, 1%, 2%, 3%) were investigated.The Sc threshold concentration in Fe:LiNbO3 was implied to be about 3%(mole fraction) because O-H vibration absorption peak of Sc (3%):Fe:LiNbO3 was at 3508 cm-1, compared with 3484 cm-1 of crystals with lower Sc doping level.Sc(3%):Fe:LiNbO3 exhibited higher optical damage resistance ability.The threshold intensity (wavelength 488 nm) of Sc (3%):Fe:LiNbO3 was 2.2×102 W·cm-2, two orders of magnitude higher than that of Fe:LiNbO3.Holographic storage properties of the crystals were determined in an extraordinary polarized laser of wavelength 632.8 nm by a two-wave coupling method.It was found that in terms of holographic storage properties, the optimal doping concentration of Sc was 2%(mole fraction) among this crystal series.

  18. Preparation and Characterization of Nano-ZnFe2O4/TiO2 Films

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The nano-ZnFe2O4/TiO2 films possess the functions of desulfurization and degradation for organic pollutants. The sols of ZnFe2O4/TiO2 were prepared by sol-gel method and coated on glass and porous ceramic by vertical coating and dipping-lift processes, respectively, and the samples were obtained after drying and sintering. The composition, appearance, absorption spectrum of the films,and the influence of the film on porous ceramic performances were analyzed using SEM, AFM, UVVis spectrometer, and mercury porosimeter, respectively, to determine the operation parameters of the multifunction porous ceramic elements for gas-purification.

  19. 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.

  20. Magnetization reversal of ultrathin Fe film grown on Si(111) using iron silicide template

    Institute of Scientific and Technical Information of China (English)

    He Wei; Zhan Qing-Feng; Wang De-Yong; Chen Li-Jun; Sun Young; Cheng Zhao-Hua

    2007-01-01

    Ultrathin Fe films were epitaxially grown on Si(111) by using an ultrathin iron silicide film with p(2 × 2) surface reconstruction as a template. The surface structure and magnetic properties were investigated in situ by low energy electron diffraction (LEED), scanning tunnelling microscopy (STM), and surface magneto-optical effect (SMOKE). Polar SMOKE hysteresis loops demonstrate that the Fe ultrathin films with thickness t< 6 ML (monolayers) exhibit perpendicular magnetic anisotropy. The characters of M-H loops with the external magnetic field at difference angles and the angular dependence of coercivity suggest that the domain-wall pinning plays a dominant role in the magnetization reversal process.

  1. Chemical synthesis of Fe{sub 2}O{sub 3} thin films for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Kulal, P.M.; Dubal, D.P.; Lokhande, C.D. [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India); Fulari, V.J., E-mail: vijayfulari@gmail.com [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India)

    2011-02-03

    Research highlights: > Simple chemical synthesis of Fe{sub 2}O{sub 3}. > Formation of amorphous and hydrous Fe{sub 2}O{sub 3}. > Potential candidate for supercapacitors. - Abstract: Fe{sub 2}O{sub 3} thin films have been prepared by novel chemical successive ionic layer adsorption and reaction (SILAR) method. Further these films were characterized for their structural, morphological and optical properties by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, scanning electron microscopy (SEM), wettability test and optical absorption studies. The XRD pattern showed that the Fe{sub 2}O{sub 3} films exhibit amorphous in nature. Formation of iron oxide compound was confirmed from FTIR studies. The optical absorption showed existence of direct optical band gap of energy 2.2 eV. Fe{sub 2}O{sub 3} film surface showed superhydrophilic nature with water contact angle less than 10{sup o}. The supercapacitive properties of Fe{sub 2}O{sub 3} thin film investigated in 1 M NaOH electrolyte showed supercapacitance of 178 F g{sup -1} at scan rate 5 mV/s.

  2. 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.

  3. Anomalous Hall effect and perpendicular magnetic anisotropy in Sm{sub 28}Fe{sub 72} and Sm{sub 32}Fe{sub 68} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kamala Bharathi, K., E-mail: kbkaruppanan@utep.ed [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Venkatesh, S. [Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005 (India); Markandeyulu, G. [Advanced Magnetic Materials Laboratory (AMMLa), Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Ramana, C.V. [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States)

    2011-01-15

    Sm{sub 28}Fe{sub 72} and Sm{sub 32}Fe{sub 68} films of 100 nm thickness were grown using DC magnetron sputter deposition and their structure, magnetization, electrical and Hall resistance characteristics were investigated. An increase in electrical resistivity from 4.75x10{sup -6} to 5.62x10{sup -6} {Omega} m and from 2.26x10{sup -6} to 2.84x10{sup -6} {Omega} m for Sm{sub 28}Fe{sub 72} and Sm{sub 32}Fe{sub 68} films, respectively, with decrease in temperature from 300 to 40 K is attributed to the strain induced anisotropy that dominates at lower temperatures. The positive extraordinary Hall coefficients (R{sub S}) are observed for both films at 300 and 80 K. The existence of hysteresis indicates that Sm{sub 28}Fe{sub 72} and Sm{sub 32}Fe{sub 68} films possess perpendicular anisotropy at 300 K. Hysteresis loop becomes narrow at 80 K for both Sm{sub 28}Fe{sub 72} and Sm{sub 32}Fe{sub 68} films. Magnetization measurements at 300 K exhibiting small coercive field values of 31 and 49 Oe for Sm{sub 28}Fe{sub 72} and Sm{sub 32}Fe{sub 68} films, respectively, confirm the existence of perpendicular anisotropy at 300 K.

  4. Single crystals of superconducting SmFeAsO Hx : Structure and properties

    Science.gov (United States)

    Pisoni, A.; Katrych, S.; Arakcheeva, A.; Verebélyi, T.; Bokor, M.; Huang, P.; Gaál, R.; Matus, P.; Karpinski, J.; Forró, L.

    2016-07-01

    We report the synthesis, structure, and superconducting properties of single crystals of SmFeAsO Hx . The crystals were grown at high pressure and high temperature using a cubic anvil technique. 1H-NMR studies confirm the presence of H atoms in the samples. Single crystal x-ray diffraction analyses demonstrate a remarkable disorder in the S m2O2 layers induced by hydrogen incorporation and reveal that the H positions are compatible with a H2O -like geometry inside the crystals. We have measured the magnetotransport properties of SmFeAsO Hx single crystals with x =0.07 , 0.11, and 0.16 in magnetic field up to 16 T, oriented along the two main crystallographic directions. The results show an increase of the critical temperature with hydrogen content. The zero-temperature upper critical fields and the magnetic anisotropy are calculated as a function of the hydrogen content. SmFeAsO Hx crystals present significantly higher upper critical fields and magnetic anisotropies compared to SmFeAs O1 -xFx compounds.

  5. Kinetics of crystallization of a Fe-based multicomponent amorphous alloy

    Indian Academy of Sciences (India)

    Arun Pratap; T Lilly Shanker Rao; Kinnary Patel; Mukesh Chawda

    2009-10-01

    The Fe-based multicomponent amorphous alloys (also referred to as metallic glasses) are known to exhibit soft magnetic properties and, it makes them important for many technological applications. However, metallic glasses are in a thermodynamically metastable state and in case of high temperature operating conditions, the thermally activated crystallization would be detrimental to their magnetic properties. The study of crystallization kinetics of metallic glasses gives useful insight about its thermal stability. In the present work, crystallization study of Fe67Co18B14Si1 (2605CO) metallic glass has been carried out using differential scanning calorimetry (DSC) technique. Mössbauer study has also been undertaken to know the phases formed during the crystallization process. The alloy shows two-stage crystallization. The activation energy has been derived using the Kissinger method. It is found to be equal to 220 kJ/mol and 349 kJ/mol for the first and second crystallization peaks, respectively. The Mössbauer study indicates the formation of -(Fe, Co) and (Fe, Co)3B phases in the alloy.

  6. TiO2 and Fe2O3 films for photoelectrochemical water splitting.

    Science.gov (United States)

    Krysa, Josef; Zlamal, Martin; Kment, Stepan; Brunclikova, Michaela; Hubicka, Zdenek

    2015-01-09

    Titanium oxide (TiO2) and iron oxide (α-Fe2O3) hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and α-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS) and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC) water splitting conditions. It was revealed that the HiPIMS method already provides crystalline structures of anatase TiO2 and hematite Fe2O3 during the deposition, whereas to finalize the sol-gel route the as-deposited films must always be annealed to obtain the crystalline phase. Regarding the PEC activity, both TiO2 films show similar photocurrent density, but only when illuminated by UV light. A different situation was observed for hematite films where plasmatic films showed a tenfold enhancement of the stable photocurrent density over the sol-gel hematite films for both UV and visible irradiation. The superior properties of plasmatic film could be explained by ability to address some of the hematite drawbacks by deposition of very thin films (25 nm) consisting of small densely packed particles and by doping with Sn.

  7. TiO2 and Fe2O3 Films for Photoelectrochemical Water Splitting

    Directory of Open Access Journals (Sweden)

    Josef Krysa

    2015-01-01

    Full Text Available Titanium oxide (TiO2 and iron oxide (α-Fe2O3 hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and α-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC water splitting conditions. It was revealed that the HiPIMS method already provides crystalline structures of anatase TiO2 and hematite Fe2O3 during the deposition, whereas to finalize the sol-gel route the as-deposited films must always be annealed to obtain the crystalline phase. Regarding the PEC activity, both TiO2 films show similar photocurrent density, but only when illuminated by UV light. A different situation was observed for hematite films where plasmatic films showed a tenfold enhancement of the stable photocurrent density over the sol-gel hematite films for both UV and visible irradiation. The superior properties of plasmatic films could be explained by ability to address some of the hematite drawbacks by the deposition of very thin films (25 nm consisting of small densely packed particles and by doping with Sn.

  8. Mössbauer spectroscopy of Fe 60Ni 40 alloy films

    Science.gov (United States)

    Mahmood, Sami H.; Rousan, Khitam K.; Lehlooh, A.-F.; Mahmoud, Sabri S.

    1995-09-01

    Films of the alloy Fe 60Ni 40 are prepared by thermal evaporation of the alloy powder onto Al foils. Mössbauer spectra of the films on the Al substrate show a dominent central paramagnetic line during the first month after their preparation, which is attributed to the Fe-rich γ' f.c.c. phase. The spectrum collected four months after preparation shows a 25% decrease in the relative intensity of the paramagnetic signal. However, the paramagnetic intensity drops by 65% upon removal of the film from the substrate, reaching a value close to that for the original alloy powder. This is interpreted as due to the atomic diffusion of Fe atoms from Fe-rich clusters into the surrounding FeNi matrix, and the occurrence of a phase relaxation to a state similar to that of the original powder, implying that the relative proportion of the γ' phase could be dictated by the chemical composition of the alloy.

  9. Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films.

    Science.gov (United States)

    Song, Can-Li; Zhang, Hui-Min; Zhong, Yong; Hu, Xiao-Peng; Ji, Shuai-Hua; Wang, Lili; He, Ke; Ma, Xu-Cun; Xue, Qi-Kun

    2016-04-15

    We report on the emergence of two disconnected superconducting domes in alkali-metal potassium- (K-)doped FeSe ultrathin films grown on graphitized SiC(0001). The superconductivity exhibits hypersensitivity to K dosage in the lower-T_{c} dome, whereas in the heavily electron-doped higher-T_{c} dome it becomes spatially homogeneous and robust against disorder, supportive of a conventional Cooper-pairing mechanism. Furthermore, the heavily K-doped multilayer FeSe films all reveal a large superconducting gap of ∼14  meV, irrespective of film thickness, verifying the higher-T_{c} superconductivity only in the topmost FeSe layer. The unusual finding of a double-dome superconducting phase is a step towards the mechanistic understanding of superconductivity in FeSe-derived superconductors.

  10. Giant magneto-optical Faraday effect of nanometer Fe-In2O3 granular films

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin; ZHANG LianSheng; XIAO ShuQin

    2008-01-01

    The giant magneto-optical Faraday effect of nanometer ferromagnetic metal-semiconductor matrix Fe-In2O3 granular films prepared by the radio frequency sputtering are studied. The result shows that the Faraday rotation angle θF value of the granular film samples with Fe volume fraction x=35% is of the order of 105(°)/cm at room temperature. Temperature dependence of the Faraday rotation angle θF of Fe0.35(In2O2)0.65 granular films shows that θF value below 10 K increases rapidly with the decrease of the temperature, and when T=4.2 K,θF value is 106(°)/cm. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that when the temperature decreases to a critical point TP=10K, the transformation of state from ferro-magnetic to spin-glass-like occurs in Fe0.35(In2O3)0.65 granular films. The remarkable increase of the Faraday rotation angle eF value of Fe0.35(In2O3)0.65 granular films below 10 K seems to arise from the sp-d exchange interaction of the granular film samples in the spin-glass-like state.

  11. Self-cleaning glass coated with Fe3+-TiO2 thin film

    Institute of Scientific and Technical Information of China (English)

    卢安贤; 林娜; 李雪; 谭常优

    2004-01-01

    The self-cleaning glass coated with Fe3+-TiO2 photocatalytic thin film was prepared by sol-gel process from the system Ti(OC4H9)4-NH(C2H4OH)2-C2H5OH-H2O containing FeCl3. The microstructure and properties of the film were studied using differential thermal analysis-thermogravimetry(DTA-TG), X-ray diffration(XRD) and scanning electron microscope(SEM). The transmittance of the self-cleaning glass was measured by using UV-Vis spectrometer. The effects of content of Fe3+ and the thickness of Fe3+-TiO2 thin film on the photocatalytic activity were examined. The results show that the photocatalytic thin films are mainly composed of Fe3O4 and TiO2 particles within 10-100 nm. The appropriate amount of Fe3+ is effective for improving the photocatalytic activities of TiO2. The best photocatalytic activity is obtained when the molar ratio of Fe3+ to TiO2 is 0.005 and the glass is coated with 9 layers.

  12. On the interpretation of {sup 57}Fe Moessbauer spectra from CdTe thin films with substitutions of Fe, In, and Sb

    Energy Technology Data Exchange (ETDEWEB)

    Yee-Madeira, H. [Centro de Investigacion y de Estudios Avanzados, IPN, Mexico City (Mexico). Dept. de Fisica]|[Depto. de Fisica, Esc. Sup. de Fisica y Matematicas (ESFM) del IPN, Edif. 9, U. P. ALM, 07738, Mexico D.F. (Mexico); Reguera, E.; Zelaya-Angel, O.; Sanchez-Sinencio, F. [Centro de Investigacion y de Estudios Avanzados, IPN, Mexico City (Mexico). Dept. de Fisica; Montiel-Sanchez, H. [Depto. de Fisica, Esc. Sup. de Fisica y Matematicas (ESFM) del IPN, Edif. 9, U. P. ALM, 07738, Mexico D.F. (Mexico); Scorzelli, R.B. [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150, CEP 22290, Urca, Rio de Janeiro (Brazil)

    1999-02-26

    {sup 57}Fe Moessbauer spectra of well characterized CdTe thin films with substitutions of Fe, In and Sb were recorded and interpreted according to the changes in the ionic radii and electronic properties of these substitutions relative to Cd in the CdTe framework. The literature reports of certain correlations among the iron valence, Fe{sup 2+} or Fe{sup 3+}, and the crystallinity of the films are critically discussed and an explanation of their origin is provided. The Moessbauer results also allow direct understanding of the effect of In and Sb substitutions on the properties of the films. (orig.) 22 refs.

  13. Optical characteristics of an epitaxial Fe3Si/Si(111) iron silicide film

    Science.gov (United States)

    Tarasov, I. A.; Popov, Z. I.; Varnakov, S. N.; Molokeev, M. S.; Fedorov, A. S.; Yakovlev, I. A.; Fedorov, D. A.; Ovchinnikov, S. G.

    2014-07-01

    The dispersion of the relative permittivity ɛ of a 27-nm-thick epitaxial Fe3Si iron silicide film has been measured within the E = 1.16-4.96 eV energy range using the spectroscopic ellipsometry technique. The experimental data are compared to the relative permittivity calculated in the framework of the density functional theory using the GGA-PBE approximation. For Fe3Si, the electronic structure and the electronic density of states (DOS) are calculated. The analysis of the frequencies corresponding to the transitions between the DOS peaks demonstrates qualitative agreement with the measured absorption peaks. The analysis of the single wavelength laser ellipsometry data obtained in the course of the film growth demonstrates that a continuous layer of Fe3Si iron silicide film is formed if the film thickness achieves 5 nm.

  14. Structure determination of thin CoFe films by anomalous x-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gloskovskii, Andrei; Stryganyuk, Gregory; Ouardi, Siham [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Fecher, Gerhard H.; Felser, Claudia [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden (Germany); Hamrle, Jaroslav; Pistora, Jaromir [Department of Physics and Nanotechnology Centre, VSB-Technical University of Ostrava, 70833 Ostrava (Czech Republic); Bosu, Subrojati; Saito, Kesami; Sakuraba, Yuya; Takanashi, Koki [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan)

    2012-10-01

    This work reports on the investigation of structure-property relationships in thin CoFe films grown on MgO. Because of the very similar scattering factors of Fe and Co, it is not possible to distinguish the random A2 (W-type) structure from the ordered B2 (CsCl-type) structure with commonly used x-ray sources. Synchrotron radiation based anomalous x-ray diffraction overcomes this problem. It is shown that as grown thin films and 300 K post annealed films exhibit the A2 structure with a random distribution of Co and Fe. In contrast, films annealed at 400 K adopt the ordered B2 structure.

  15. Local leakage current behaviours of BiFeO3 films

    Institute of Scientific and Technical Information of China (English)

    Zou Cheng; Chen Bin; Zhu Xiao-Jian; Zuo Zheng-Hu; Liu Yi-Wei; Chen Yuan-Fu; Zhan Qing-Feng; Li Run-Wei

    2011-01-01

    The leakage current behaviours of polycrystalline BiFeO3 thin films are investigated by using both conductive atomic force microscopy and current-voltage characteristic measurements.The local charge transport pathways are found to be located mainly at the grain boundaries of the films.The leakage current density can be tuned by changing the post-annealing temperature,the annealing time,the bias voltage and the light illumination,which can be used to improve the performances of the ferroelectric devices based on the BiFeO3 films.A possible leakage mechanism is proposed to interpret the charge transports in the polycrystalline BiFeO3 films.

  16. 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.

  17. Structure and magnetic properties of nanocomposite (Nd, Dy)-(Fe, Co)-B/alpha-Fe thin films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Q; Liu, W; Cui, W B; Yang, F; Zhao, X G; Zhang, Z D, E-mail: wliu@imr.ac.c [Shenyang National Laboratory for Materials Science, Institute of Metal Research and International Center for Materials Physics, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2009-02-07

    Exchange coupling is observed in the (Nd, Dy)-(Fe, Co)-B/alpha-Fe films with perpendicular magnetic anisotropy, with a maximum energy product (BH){sub max} of 16.2 MGOe and a coercivity {sub i}H{sub c} of 11.2 kOe. The existence of soft alpha-Fe in the films is verified by the two-step reversal process at low temperatures and x-ray diffraction as well as x-ray photoelectron spectroscopy analysis. In comparison with its single-phase counterpart, the anisotropic (Nd, Dy)-(Fe, Co)-B/alpha-Fe film displays a more inhomogeneous magnetic-domain structure. The aligned nanocomposite film demonstrates anisotropic demagnetization behaviour, with the homogeneous reversal process becoming inhomogeneous as the field deviates from perpendicular to parallel to the film plane.

  18. Correlation between perpendicular magnetic anisotropy and microstructure in TbFeCo and TbFeCo-SiO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z; Zhou, S M [Surface Physics Laboratory (National Key Laboratory) and Department of Physics, Fudan University, Shanghai 200433 (China); Jiao, X B [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2009-01-07

    Both TbFeCo and TbFeCo-SiO{sub 2} films were prepared by magnetron sputtering. At a film thickness of less than 75 nm, TbFeCo-SiO{sub 2} films have coercivity and perpendicular magnetic anisotropy larger than those of TbFeCo films and vice versa at a film thickness of more than 75 nm. This phenomenon can be attributed to enhancement in the degree of preferred orientation of TbFeCo grains. For these two series of samples, the magnetization reversal process is accompanied by the combination of pinned domain wall motion (DWM) and domain rotation. The weak pinning of DWM cannot be excluded.

  19. Nanoparticle films and photonic crystal multilayers from colloidally stable, size-controllable zinc and iron oxide nanoparticles.

    Science.gov (United States)

    Redel, Engelbert; Mirtchev, Peter; Huai, Chen; Petrov, Srebri; Ozin, Geoffrey A

    2011-04-26

    We report a facile sol-gel synthesis of colloidally stable Fe(2)O(3) and ZnO nanoparticles in alcoholic solvents, ROH, where R = methyl, ethyl, n-propyl, isopropyl, and tert-butyl. We show that nanoparticles of ZnO (4-42) nm and Fe(2)O(3) (4-38 nm) monotonically increase in size upon increasing the alkyl chain length and branching of the alcohol solvent. These colloidally stable and size-controllable metal oxide nanoparticles enable the formation of high optical quality films and photonic crystal multilayers whose component layer thickness, refractive index, porosity, and surface area are found to scale with the nature of the alcohol. Utility of these colloidally stable nanoparticles is demonstrated by preparation of one-dimensional porous photonic crystals comprising ncZnO/ncWO(3) and ncFe(2)O(3)/ncWO(3) multilayers whose photonic stop band can be tuned by tailoring nanoparticle size. Myriad applications can be envisaged for these nanoparticle films in, for example, heterogeneous catalysis, photocatalysis, electrocatalysis, chemical sensors, and solar cells.

  20. Synthesis of BiFeO3 thin films on single-terminated Nb : SrTiO3 (111 substrates by intermittent microwave assisted hydrothermal method

    Directory of Open Access Journals (Sweden)

    Ivan Velasco-Davalos

    2016-06-01

    Full Text Available We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO3 (111 substrates and the deposition of ferroelectric BiFeO3 thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO34− or Ti4+ layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d111 and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO3 single crystal substrates. Multiferroic BiFeO3 thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO3 (111 substrates. Bi(NO33 and Fe(NO33 along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO3 films on Nb : SrTiO3 (100 substrates was verified by piezoresponse force microscopy.

  1. Self-Poling of BiFeO3 Thick Films.

    Science.gov (United States)

    Khomyakova, Evgeniya; Sadl, Matej; Ursic, Hana; Daniels, John; Malic, Barbara; Bencan, Andreja; Damjanovic, Dragan; Rojac, Tadej

    2016-08-01

    Bismuth ferrite (BiFeO3) is difficult to pole because of the combination of its high coercive field and high electrical conductivity. This problem is particularly pronounced in thick films. The poling, however, must be performed to achieve a large macroscopic piezoelectric response. This study presents evidence of a prominent and reproducible self-poling effect in few-tens-of-micrometer-thick BiFeO3 films. Direct and converse piezoelectric measurements confirmed that the as-sintered BiFeO3 thick films yield d33 values of up to ∼20 pC/N. It was observed that a significant self-poling effect only appears in cases when the films are heated and cooled through the ferroelectric-paraelectric phase transition (Curie temperature TC ∼ 820 °C). These self-poled films exhibit a microstructure with randomly oriented columnar grains. The presence of a compressive strain gradient across the film thickness cooled from above the TC was experimentally confirmed and is suggested to be responsible for the self-poling effect. Finally, the macroscopic d33 response of the self-poled BiFeO3 film was characterized as a function of the driving-field frequency and amplitude.

  2. Raman scattering in La1-xSrxFeO3-δ thin films: annealing-induced reduction and phase transformation.

    Science.gov (United States)

    Islam, Mohammad A; Xie, Yujun; Scafetta, Mark D; May, Steven J; Spanier, Jonathan E

    2015-04-22

    Raman scattering in thin film La0.2Sr0.8FeO3-δ on MgO(0 0 1) collected at 300 K after different stages of annealing at selected temperatures T (300 K evolution of the spectrum signals the appearance of a possible topotactic transformation of the crystal structure from that of the rhombohedral ABO3 perovskites to that of Brownmillerite-like structure consisting of octahedrally and tetrahedrally coordinated Fe atoms.

  3. Electrochemical Preparation of La-Fe Alloy Films in Dimethylsulfoxide (DMSO)

    Institute of Scientific and Technical Information of China (English)

    袁定胜; 刘冠昆; 童叶翔

    2002-01-01

    The cyclic voltammetry and potential step methods were used to investigate the electrochemical behavior of Fe2+ and La3+ in FeCl2-LiCl-DMSO and LaCl3-LiCl-DMSO systems on Pt, Cu and Ni cathodes. The electroreduction of Fe2+ to Fe is irreversible in one step,while the electroreduction of La3+ to La is quasi-reversible. The diffusion coefficient of La3+ in LaCl3-LiCl-DMSO system at 298 K was 3.1×10-6 cm2s-1. The diffusion coefficient and transfer coefficient of Fe2+ in FeCl2-LiCl-DMSO system at 298 K were 2.54×10-6 cm2*s-1 and 0.24, respectively. La-Fe alloy films containing La from 22.7% to 37.1% (mass fraction) were prepared by potentiostatic electrolysis on Cu substrates at a deposition potential from -1.750 to -2.450 V (vs SCE). The fine La-Fe alloy films were also obtained by pulse electrolysis at a pulse current densities from 2 to 6 mA*cm-2. The surfaces of these alloy films are smooth, adhesive and uniform, and have metallic luster.

  4. Microstructure and Magnetic Properties of NdFeB Films through Nd Surface Diffusion Process

    Directory of Open Access Journals (Sweden)

    Wenfeng Liu

    2017-01-01

    Full Text Available Ta/Nd/NdFeB/Nd/Ta films were deposited by magnetron sputtering on Si (100 substrates and subsequently annealed for 30 min at 923 K in vacuum. It was found that the microstructure and magnetic properties of Ta/Nd/NdFeB/Nd/Ta films strongly depend on the NdFeB layer thickness. With NdFeB layer thickness increasing, both the grain size and the strain firstly reduce and then increase. When NdFeB layer thickness is 750 nm, the strain reaches the minimum value. Meanwhile, both the in-plane and perpendicular coercivities firstly drastically increase and then slowly decrease with NdFeB layer thickness increasing. The highest in-plane and perpendicular coercivities can be obtained at NdFeB layer thickness of 750 nm, which are 21.2 kOe and 19.5 kOe, respectively. In addition, the high remanence ratio (remanent magnetization/saturation magnetization of 0.87 can also be achieved in Ta/Nd/NdFeB (750 nm/Nd/Ta film.

  5. Fe-B-Nd-Nb metallic glass thin films for microelectromechanical systems

    Science.gov (United States)

    Phan, T. A.; Oguchi, H.; Hara, M.; Shikida, M.; Hida, H.; Ando, T.; Sato, K.; Kuwano, H.

    2013-10-01

    In the present study, we investigate the mechanical properties, residual stress, and microprocessing compatibility of Fe67.5B22.5Nd6.3Nb3.7 metallic glass thin films (Fe-MGTFs). The mechanical properties are measured using a specially designed microtensile tester. The fracture toughness of the Fe-MGTF (6.36 MPa × m1/2) is more than twice that of Si, and the highest among the thin films developed for microelectromechanical systems (MEMS) to this point. In addition, the fabrication of freestanding microcantilevers illustrates the low residual stress and high microprocessing compatibility of Fe-MGTFs. The present study verifies the great potential of Fe-MGTFs for use in MEMS.

  6. Alignment mechanism of liquid crystal in a stretched porous polymer film

    Science.gov (United States)

    Fujikake, Hideo; Kuboki, Masashi; Murashige, Takeshi; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro

    2003-09-01

    This article discusses the mechanism of nematic liquid crystal alignment in stretched porous polymer films. The polymer films were formed by extreme stretching of an isotropic porous polyolefin, such that the draw ratio was 12:1. A 6-μm-thick porous film with a high porosity coefficient of 92% revealed fine string-shaped areas that exhibited optical anisotropy due to their possessing a high degree of molecular alignment. The porous film was filled with nematic liquid crystal and then the composite film was sandwiched between transparent electrodes coated onto glass substrates, without the use of conventional alignment layers. From polarizing microscopy observations it was found that the string-like polymer areas induce liquid crystal molecular alignment. The liquid crystal cells can exhibit an electrically controlled birefringence effect. This alignment technique enables us to realize three-dimensional control of liquid crystal alignment.

  7. Magnetic, transport and thermal properties of single crystal Co{sub 2}FeGa

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P. [South West University, Department of Physics, Chongqing (China); Hong Kong University of Science and Technology, Department of Physics, Kowloon, Hong Kong (China)], E-mail: pchen@swu.edu.cn; Wu, G.H. [Beijing National Laboratory for Condensed Matter, Institute of Physics, CAS, Beijing 100080 (China); Zhang, X.X. [Hong Kong University of Science and Technology, Department of Physics, Kowloon, Hong Kong (China)

    2008-04-24

    The magnetic, transport and thermal properties of single crystal Co{sub 2}FeGa have been investigated. The small coercivity 20 Oe and saturation field 4000 Oe of Co{sub 2}FeGa sample at temperature 5 K indicates that the single crystal is magnetically soft. The resistivity ({rho}) behaves according to {rho} {approx} T{sup 1/2} power law below temperature T = 40 K, which is due to electron-electron interaction effects in the presence of disorder. The thermal conductivity of Co{sub 2}FeGa single exhibits anomalous temperature dependence above 50 K, i.e., the conductivity increases with the temperature, or d{kappa}/dT > 0. We conclude that this anomalous thermal conductivity is due to the strong atomic disorder between the Fe and Co atoms.

  8. Entrapment of Inclusions in Diamond Crystals Grown from Fe-Ni-C System

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Diamond single crystals grown from Fe-Ni-C system at high temperature-high pressure (HPHT) usually contain inclusions related to the metallic catalyst. During the diamond growth, the metallic inclusions are trapped by the growth front or are formed through reaction between the contaminants trapped in the diamond. In the present paper, the metallic inclusions related to the catalyst were systematically examined by transmission electron microscopy (TEM). The chemical composition and crystal structure of the metallic inclusions were for the first time determined by selected area electron diffraction pattern (SADP) combined with energy dispersive X-ray spectrometry (EDS). It is shown that the inclusions are mainly composed of orthorhombic FeSi2, fcc (FeNi)23C6, and orthorhombic Fe3C,hexagonal Ni3C.

  9. Structural, optical and electrical properties of Cu{sub 2}FeSnX{sub 4} (X = S, Se) thin films prepared by chemical spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Khadka, Dhruba B.; Kim, JunHo, E-mail: jhk@inu.ac.kr

    2015-07-25

    Highlights: • CFTS(Se) thin films have been synthesized by low-cost spray-based deposition. • The fabricated films were found to be of stannite structure and p-type conductivity. • Band gaps of CFTS and CFTSe thin films are 1.37 and 1.11 eV, respectively. - Abstract: We report on fabrication of polycrystalline Cu{sub 2}FeSnX{sub 4} (X = S, Se) thin films by chemical spray pyrolysis subsequent with post-sulfurization and selenization. The post-annealing of as-sprayed Cu{sub 2}FeSnS{sub 4} (CFTS) films in sulfur and selenium ambient demonstrated drastically improved surface texture as well as crystallinity. The crystal lattice parameters calculated from X-ray diffraction patterns for post-annealed films were found to be consistent with stannite structure. The fabricated Cu{sub 2}FeSnS{sub 4} (CFTS) and Cu{sub 2}FeSnSe{sub 4} (CFTSe) films showed p-type conductivity with carrier concentration in the range of 10{sup 21} cm{sup −3} and mobility ∼1–5 cm{sup 2} V{sup −1} s{sup −1}. The band gap energies of post-sulfurized CFTS and post-selenized CFTSe films were estimated to be ∼1.37 eV and ∼1.11 eV with an error of ±0.02 eV by UV–Vis absorption, respectively, which are promising for photovoltaic application.

  10. Adsorption of cobalt ferrite nanoparticles within layer-by-layer films: a kinetic study carried out using quartz crystal microbalance.

    Science.gov (United States)

    Alcantara, Gustavo B; Paterno, Leonardo G; Afonso, André S; Faria, Ronaldo C; Pereira-da-Silva, Marcelo A; Morais, Paulo C; Soler, Maria A G

    2011-12-28

    The paper reports on the successful use of the quartz crystal microbalance technique to assess accurate kinetics and equilibrium parameters regarding the investigation of in situ adsorption of nanosized cobalt ferrite particles (CoFe(2)O(4)--10.5 nm-diameter) onto two different surfaces. Firstly, a single layer of nanoparticles was deposited onto the surface provided by the gold-coated quartz resonator functionalized with sodium 3-mercapto propanesulfonate (3-MPS). Secondly, the layer-by-layer (LbL) technique was used to build multilayers in which the CoFe(2)O(4) nanoparticle-based layer alternates with the sodium sulfonated polystyrene (PSS) layer. The adsorption experiments were conducted by modulating the number of adsorbed CoFe(2)O(4)/PSS bilayers (n) and/or by changing the CoFe(2)O(4) nanoparticle concentration while suspended as a stable colloidal dispersion. Adsorption of CoFe(2)O(4) nanoparticles onto the 3-MPS-functionalized surface follows perfectly a first order kinetic process in a wide range (two orders of magnitude) of nanoparticle concentrations. These data were used to assess the equilibrium constant and the adsorption free energy. Alternatively, the Langmuir adsorption constant was obtained while analyzing the isotherm data at the equilibrium. Adsorption of CoFe(2)O(4) nanoparticles while growing multilayers of CoFe(2)O(4)/PSS was conducted using colloidal suspensions with CoFe(2)O(4) concentration in the range of 10(-8) to 10(-6) (moles of cobalt ferrite per litre) and for different numbers of cycles n = 1, 3, 5, and 10. We found the adsorption of CoFe(2)O(4) nanoparticles within the CoFe(2)O(4)/PSS bilayers perfectly following a first order kinetic process, with the characteristic rate constant growing with the increase of CoFe(2)O(4) nanoparticle concentration and decreasing with the rise of the number of LbL cycles (n). Additionally, atomic force microscopy was employed for assessing the LbL film roughness and thickness. We found the film

  11. Electronic and crystal structure analysis of the FeCrO{sub 3} oxide

    Energy Technology Data Exchange (ETDEWEB)

    Ozkendir, Osman Murat, E-mail: ozkendir@gmail.com

    2013-12-15

    Highlights: •The crystal, electronic and magnetic properties of FeCrO{sub 3} compound are investigated. •The measured data were compared with the parent oxides Cr{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}of the compound to identify the structural and electronic change during the process of FeCrO{sub 3} structure. •The electronic properties of the sample were investigated via Fe, Cr L{sub 3,2}and O K-edges and the measurements to probe magnetic properties were performed. •In the FeCrO{sub 3} structure, traces of the O{sub h} and T{sub d} site symmetric local Fe{sup 3+} formations were observed. •The Fe{sup 3+} ions with O{sub h} symmetry as in the parent oxide α-Fe{sub 2}O{sub 3} (hematite) were determined to have antiferromagnetic ordering. -- Abstract: The magnetic and electronic behaviors of FeCrO{sub 3} crystal were investigated by X-ray absorption near edge (XANES) and X-ray magnetic linear dichroism (XMLD) techniques. The measured data were compared with the parent oxides Cr{sub 2}O{sub 3} and α-Fe{sub 2}O{sub 3} of the compound to identify the structural and electronic change during the process of FeCrO{sub 3} structure. The electronic properties of the sample were investigated via Fe, Cr L{sub 3,2} and O K-edges. The XMCD measurements to probe magnetic properties were performed by an external magnetic field of 0.4 T. In the FeCrO{sub 3} structure, traces of the O{sub h} and T{sub d} site symmetric local Fe{sup 3+} formations were observed. The Fe{sup 3+} ions with O{sub h} symmetry as in the parent oxide α-Fe{sub 2}O{sub 3} (hematite) were determined to have antiferromagnetic order in the structure. However, domains who have T{sub d} site symmetry with ferrimagnetic order due to the γ-Fe{sub 2}O{sub 3} (maghemite) formation were determined.

  12. The Phase Transformations and Magnetoresistive Properties of Diluted Film Solid Solutions Based on Fe and Ge Atoms

    Directory of Open Access Journals (Sweden)

    O.V. Vlasenko

    2014-06-01

    Full Text Available In the article, the structure, phase composition and magnetoresistive properties of single- and three-layer films based on Fe and Ge were studied. It is established that in such films eutectic is formed based on diluted solid solutions of Ge atoms in -Fe layers and of Fe atoms in -Ge layers at the total concentration of Ge atoms from 3 to 20 at.% in the temperature range of 300-870 K. It is shown that magnetoresistive properties of the films with eutectic composition are not significantly different from the properties of -Fe films.

  13. Crystal structure of the ternary compound {gamma}-Al{sub 3}FeSi

    Energy Technology Data Exchange (ETDEWEB)

    Roger, Jerome; Jeanneau, Erwann; Viala, Jean-Claude [UMA CNRS no. 5615, Claude Bernard Lyon 1 Univ., Villeurbanne (France). Lab. des Multimateriaux et Interfaces

    2011-07-01

    Ternary iron silicide aluminide {gamma}-Al{sub 3}FeSi crystals were grown from two Al-Fe-Si melts quenched in cold water. The crystal structures were determined from single-crystal X-ray data: trigonal symmetry, space group R-3 (n 148), unit cell parameters a = 10.2223(2) A, c = 19.6791(4) A (V = 1781 A{sup 3}) for the Si-poorer crystal and a = 10.1987(2) A, c = 19.5320(3) A (V = 1759 A{sup 3}) for the Si-richer one. The structure of {gamma}-Al{sub 3}FeSi may be described in terms of Al-cubes connected together by Al-Al pairs. The structure contains also Al cuboctaedra with one Fe-Al mixed atom in the center. The average chemical formula obtained from the refinements is Al{sub 3}FeSi. This phase shows a partial disorder on the aluminium network because of the substitution of aluminum atoms by silicon. This substitution mechanism is at the origin of the large homogeneity range of this phase. (orig.)

  14. Magnetic resonance in ion-beam synthesized Fe{sub 3}Si films (computer simulation)

    Energy Technology Data Exchange (ETDEWEB)

    Balakirev, N.A.; Zhikharev, V.A. [Kazan National Research Technological University, Kazan (Russian Federation)

    2015-01-01

    High dose Fe{sup +} ion implantation into Si assisted by an external magnetic field parallel to silicon surface results in the formation of thin granular film with pronounced uniaxial magnetic anisotropy in the film plane. It was suggested that the anisotropy is caused by the growth of elongated clusters of magnetic silicide Fe{sub 3}Si. In the present work, the features of magnetic resonance spectra for two-dimensional array of elongated clusters are numerically studied. Absorption spectra reveal anisotropy when observed in the magnetic field lying in the film plane. In magnetic field perpendicular to the film the dipole-dipole interaction between the clusters results in a bimodal resonance signal at low level of the film filling. The dipolar field distribution over the (400x400) lattice for several values of the lattice filling is computer simulated. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Large Area Single Crystal (0001) Oriented MoS2 Thin Films

    OpenAIRE

    Laskar, Masihhur R.; Ma, Lu; K, ShanthaKumar; Park, Pil Sung; Krishnamoorthy, Sriram; Nath, Digbijoy N.; Lu, Wu; Wu, Yiying; Rajan, Siddharth

    2013-01-01

    Layered metal dichalcogenide materials are a family of semiconductors with a wide range of energy band gaps and properties, and potential to open up new areas of physics and technology applications. However, obtaining high crystal quality thin films over a large area remains a challenge. Here we show that chemical vapor deposition (CVD) can be used to achieve large area electronic grade single crystal Molybdenum Disulfide (MoS2) thin films with the highest mobility reported in CVD grown films...

  16. 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.

  17. Cu clustering stage before the crystallization in Fe-Si-B-Nb-Cu amorphous alloys

    DEFF Research Database (Denmark)

    Ohnuma, M.; Hono, K.; Onodera, H.

    1999-01-01

    The Cu clustering stage before the crystallization of Fe-Si-B-Nb-Cu amorphous alloys have been studied by three dimensional atom probe (3DAP) small-angle neutron scattering (SANS) and high sensitive differential calorimetry (DSC). Cu clustering occurs prior to the onset of the primary crystalliza......The Cu clustering stage before the crystallization of Fe-Si-B-Nb-Cu amorphous alloys have been studied by three dimensional atom probe (3DAP) small-angle neutron scattering (SANS) and high sensitive differential calorimetry (DSC). Cu clustering occurs prior to the onset of the primary...

  18. Crystal Structures of Fe2+ Dioxygenase Superoxo, Alkylperoxo, and Bound Product Intermediates

    OpenAIRE

    Kovaleva, Elena G.; Lipscomb, John D.

    2007-01-01

    We report the structures of three intermediates in the O2 activation and insertion reactions of an extradiol ring-cleaving dioxygenase. A crystal of Fe2+-containing homoprotocatechuate 2,3-dioxygenase was soaked in the slow substrate 4-nitrocatechol in a low O2 atmosphere. The X-ray crystal structure shows that three different intermediates reside in different subunits of a single homotetrameric enzyme molecule. One of these is the key substrate-alkylperoxo-Fe2+ intermediate, which has been p...

  19. Multiscale simulation and nanoindentation experimental study of initial plasticity of Fe single crystal

    Institute of Scientific and Technical Information of China (English)

    YUAN Lin; SHAN De-bin; GUO Bin

    2009-01-01

    It is very important to understand the initial plastic behavior of metals at microscale. In order to research the initial plasticity of body centered cubic metals in micro-/nano-scale, the multiscale simulation method and experimental study were used to study the nanoindentation process of Fe single crystal. The results show that the first abruption of load-displacement curve in nanoindentation of Fe single crystal can be attributed to the first transition from elastic to plastic deformation characterized by the dislocation emission.

  20. Selective scattering polymer dispersed liquid crystal film for light enhancement of organic light emitting diode.

    Science.gov (United States)

    Jiang, Jinghua; McGraw, Greg; Ma, Ruiqing; Brown, Julie; Yang, Deng-Ke

    2017-02-20

    We developed a novel light enhancing film for an organic light emitting diode (OLED) based on polymer dispersed liquid crystal (PDLC). In the film, the liquid crystal droplets are unidirectionally aligned along the film normal direction and exhibit selective scattering. The film scatters light emitted only in directions with large incident angles but not light emitted in directions with small incident angles. When the light is scattered, it changes propagation direction and exits the OLED. The PDLC film reduces the total internal reflection and thus can significantly increase the light efficiency of the OLED.

  1. Fabrication and structure of Langmuir-Blodgett films of ferroelectric liquid crystal

    Institute of Scientific and Technical Information of China (English)

    WEN Zi; JIANG Qing; T.Kenji; O.Yukihiro

    2005-01-01

    The molecular aggregation, orientation, and structure in Langmuir-Blodgett films of ferroelectric liquid crystal were studied by ultraviolet and Fourier transform infrared spectra. The results show that medium strong H-aggregates in the Langmuir-Blodgett films of ferroelectric liquid crystal are formed by chromophores where the alkyl chains are nearly perpendicular to the film surface. Compared with the cast films, the CO stretching bands, due to the rotational isomerism around the O-C axis of the chiral part, can be identified clearly in Langmuir-Blodgett films.

  2. In situ X-ray diffraction based investigation of crystallization in solution deposited PZT thin films

    Science.gov (United States)

    Nittala, Krishna

    Solution deposited PZT based thin films have potential applications in embedded decoupling capacitors and pulse discharge capacitors. During solution deposition, precursor solution is deposited onto a substrate to obtain an amorphous film. The film is then crystallized by heating it at a high temperature (˜600 - 700°C). Conditions during the crystallization anneal such as precursor stoichiometry in solution, heating rate and adhesion layer in the substrate are known to influence phase and texture evolution in these films. However, a mechanistic understanding of the changes taking place in these thin films during crystallization is lacking. A better understanding of the crystallization processes in these thin films could enable tailoring the properties of thin films to suit specific applications. To explore the crystallization process in solution deposited PZT thin films, high temperature in situ laboratory and synchrotron X-ray diffraction based techniques were developed. Taking advantage of the high X-ray flux available at synchrotron facilities such as beamline 6-ID-B, Advanced Photon Source, Argonne National Laboratory, crystalline phases formed in the thin films during crystallization at the high heating rates (0.5 -- 60°C/s) typically used during film processing could be measured. Using a 2-D detector for these measurements allowed the simultaneous measurement of both phase and texture information during crystallization. Analytical treatment of the unconventional diffraction geometry used during the synchrotron based measurements was performed to develop methodologies for quantitative estimation of texture components. The nominal lead content in the starting solutions and the heating rate used during crystallization was observed to influence the sequence of phases formed during crystallization of the films. In films crystallized at fast heating rates, titanium segregation, probably due to diffusion of titanium from the adhesion layer, was observed. To

  3. Effects of Ag addition on FePt L10 ordering transition: A direct observation of ordering transition and Ag segregation in FePtAg alloy films

    Science.gov (United States)

    Wang, Lei; Gao, Tenghua; Yu, Youxing

    2015-12-01

    FePt and (FePt)91.2Ag8.8 alloy films were deposited by magnetron sputtering. The average coercivity of (FePt)91.2Ag8.8 films reaches 8.51 × 105 A/m, which is 0.63 × 105 A/m higher than that of the corresponding FePt films. Ag addition effectively promotes the FePt L10 ordering transition at a relatively low annealing temperature of 400 °C. The promotion mechanism was investigated by using in situ high-resolution transmission electron microscopy (HRTEM) and ex situ X-ray absorption fine structure (XAFS). The concurrence of ordering transition and Ag segregation in FePtAg alloy films was first observed by using in situ heating HRTEM. The time-resolved evolution reveals more details on the role of Ag addition in FePt low-temperature ordering. Ex situ XAFS results further confirm that Ag replaces Fe sites in the as-deposited films and segregates from FePt-Ag solid solution phase through annealing at elevated temperatures. The segregation of Ag atoms leaves vacancies in the grain. The vacancy formation is believed to accelerate the diffusion of Fe and Pt atoms, which is critical for the L10 ordering transition.

  4. Fe-Doped TiO2 Thin Films for CO Gas Sensing

    Science.gov (United States)

    Kumar, Mukesh; Kumar, Dinesh; Gupta, Anil Kumar

    2015-01-01

    Fe-doped TiO2 thin films were prepared by the sol-gel technique on silicon substrate. The thin films were evaluated for detection of carbon monoxide (CO) gas at room temperature. The TiO2 films were characterized by x-ray diffraction (XRD) analysis, field-emission scanning electron microscopy, and ultraviolet-visible (UV) spectroscopy. The characterization revealed that, as the doping concentration was increased, the grain size decreased. XRD patterns revealed the phase transition from rutile to anatase with addition of different percentages (weight/volume) of Fe. The bandgap determined from UV spectroscopy was found to decrease with increasing Fe doping concentration. Fe doping was observed to have a significant effect on the resistivity of the doped TiO2 thin films. The gas sensing behavior of the films was studied by exposure to different concentrations of CO gas with measurement of the electrical resistance. It was observed that Fe-doped (7% weight/volume) TiO2 exhibited high sensitivity and good response/recovery on exposure to CO gas in the concentration range from 100 ppm to 900 ppm in Ar.

  5. Inverse magnetoresistance in textured Fe{sub 3}O{sub 4} film

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Er, E-mail: liuer1986@gmail.com [Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189 (China); Zhang, Wen [Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189 (China); Zheng, Jian-Guo [Irvine Materials Research Institute, University of California, Irvine, CA 92697-2800 (United States); Hu, Xuefeng [Department of Electronics, The University of York, York YO10 5DD (United Kingdom); Ou, Huiling; Du, Ruxia; Kou, Chaoxia [Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189 (China); Zhai, Ya, E-mail: yazhai@seu.edu.cn [Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189 (China); National Laboratory of Solid Microstructures, Nanjing University, Nanjing 210093 (China); Xu, Qingyu [Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189 (China); Du, Jun [National Laboratory of Solid Microstructures, Nanjing University, Nanjing 210093 (China); Xu, Yongbing [Department of Electronics, The University of York, York YO10 5DD (United Kingdom); Zhai, Hongru [Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189 (China); National Laboratory of Solid Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-11-15

    A surprising inverse (positive) MR effect was observed in thin film of magnetite (Fe{sub 3}O{sub 4}) grown on Si substrate by pulsed laser deposition (PLD). Transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements show a highly (111)-textured growth and single phase nature of Fe{sub 3}O{sub 4} thin film. X-Ray Magnetic Circular Dichroism (XMCD) and X-ray absorption spectroscopy (XAS) were employed to exclude the existence of γ-Fe{sub 2}O{sub 3}. The surface morphology of the film was investigated by atomic force microscopy (AFM). Based on the aforementioned studies, we proposed a spin dependent conduction mechanism to explain the observed anomalous MR effect. - Highlights: • A positive magnetoresistance (MR) effect was observed on our Fe{sub 3}O{sub 4}/Si film. • The unique MR effect is distinct from the usual MR effect in Fe{sub 3}O{sub 4} film. • HRTEM, XRD, AFM and XMCD techniques are performed to study the anomalous MR effect. • We proposed a new conduction mechanism to explain the anomalous MR effect.

  6. High-loading Fe2O3/SWNT composite films for lithium-ion battery applications

    Science.gov (United States)

    Wang, Ying; Guo, Jiahui; Li, Li; Ge, Yali; Li, Baojun; Zhang, Yingjiu; Shang, Yuanyuan; Cao, Anyuan

    2017-08-01

    Single-walled carbon nanotube (SWNT) films are a potential candidate as porous conductive electrodes for energy conversion and storage; tailoring the loading and distribution of active materials grafted on SWNTs is critical for achieving maximum performance. Here, we show that as-synthesized SWNT samples containing residual Fe catalyst can be directly converted to Fe2O3/SWNT composite films by thermal annealing in air. The mass loading of Fe2O3 nanoparticles is tunable from 63 wt% up to 96 wt%, depending on the annealing temperature (from 450 °C to 600 °C), while maintaining the porous network structure. Interconnected SWNT networks containing high-loading active oxides lead to synergistic effect as an anode material for lithium ion batteries. The performance is improved consistently with increasing Fe2O3 loading. As a result, our Fe2O3/SWNT composite films exhibit a high reversible capacity (1007.1 mA h g-1 at a current density of 200 mA g-1), excellent rate capability (384.9 mA h g-1 at 5 A g-1) and stable cycling performance with the discharge capacity up to 567.1 mA h g-1 after 600 cycles at 2 A g-1. The high-loading Fe2O3/SWNT composite films have potential applications as nanostructured electrodes for various energy devices such as supercapacitors and Li-ion batteries.

  7. Characterization of β-FeSi II films as a novel solar cell semiconductor

    Science.gov (United States)

    Fukuzawa, Yasuhiro; Ootsuka, Teruhisa; Otogawa, Naotaka; Abe, Hironori; Nakayama, Yasuhiko; Makita, Yunosuke

    2006-04-01

    β-FeSi II is an attractive semiconductor owing to its extremely high optical absorption coefficient (α>10 5 cm -1), and is expected to be an ideal semiconductor as a thin film solar cell. For solar cell use, to prepare high quality β-FeSi II films holding a desired Fe/Si ratio, we chose two methods; one is a molecular beam epitaxy (MBE) method in which Fe and Si were evaporated by using normal Knudsen cells, and occasionally by e-gun for Si. Another one is the facing-target sputtering (FTS) method in which deposition of β-FeSi II films is made on Si substrate that is placed out of gas plasma cloud. In both methods to obtain β-FeSi II films with a tuned Fe/Si ratio, Fe/Si super lattice was fabricated by varying Fe and Si deposition thickness. Results showed significant in- and out-diffusion of host Fe and Si atoms at the interface of Si substrates into β-FeSi II layers. It was experimentally demonstrated that this diffusion can be suppressed by the formation of template layer between the epitaxial β-FeSi II layer and the substrate. The template layer was prepared by reactive deposition epitaxy (RDE) method. By fixing the Fe/Si ratio as precisely as possible at 1/2, systematic doping experiments of acceptor (Ga and B) and donor (As) impurities into β-FeSi II were carried out. Systematical changes of electron and hole carrier concentration in these samples along variation of incorporated impurities were observed through Hall effect measurements. Residual carrier concentrations can be ascribed to not only the remaining undesired impurities contained in source materials but also to a variety of point defects mainly produced by the uncontrolled stoichiometry. A preliminary structure of n-β-FeSi II/p-Si used as a solar cell indicated a conversion efficiency of 3.7%.

  8. Bulk Superconductivity and Disorder in Single Crystals of LaFePO

    Energy Technology Data Exchange (ETDEWEB)

    Analytis, James G.; Chu, Jiun-Haw; Erickson, Ann S.; Kucharczyk, Chris; /Stanford U., Appl. Phys. Dept.; Serafin, Alessandro; Carrington, Antony; /Bristol U.; Cox, Catherine; Kauzlarich, Susan M.; Hope, Hakon; /UC, Davis. Dept. Chem.

    2010-02-15

    We have studied the intrinsic normal and superconducting properties of the oxypnictide LaFePO. These samples exhibit bulk superconductivity and the evidence suggests that stoichiometric LaFePO is indeed superconducting, in contrast to other reports. We find that superconductivity is independent of the interplane residual resistivity {rho}{sub 0} and discuss the implications of this on the nature of the superconducting order parameter. Finally we find that, unlike T{sub c}, other properties in single-crystal LaFePO including the resistivity and magnetoresistance, can be very sensitive to disorder.

  9. Electrochemical preparation of La-Co-Fe alloy films in dimethylsulfoxide (DMSO)

    Institute of Scientific and Technical Information of China (English)

    袁定胜; 黄开胜; 刘冠昆; 童叶翔; 沙励嫦

    2001-01-01

    Potentiostatic and pulse electrolysis techniques were used to prepare La-Co-Fe alloy films using ethylenediamine (EN) as complexant. Surfaces of alloy films obtained by these two techniques are smooth, adhesive, compact and metallic luster. The contents of La in alloy films obtained by potentiostatic electrolysis technique are in the range of 13.23%~47.67%. The contents of La in alloy films deposited by pulse electrolysis technique are in the range of 10.67%~16.29%.

  10. Photodriven spin change of Fe(II) benzimidazole compounds anchored to nanocrystalline TiO(2) thin films.

    Science.gov (United States)

    Xia, Hai-Long; Ardo, Shane; Narducci Sarjeant, Amy A; Huang, Sunxiang; Meyer, Gerald J

    2009-12-01

    Ferrous tris-chelate compounds based on 2-(2'-pyridyl)benzimidazole (pybzim) have been prepared and characterized for studies of spin equilibria in fluid solution and when anchored to the surface of mesoporous nanocrystalline (anatase) TiO(2) and colloidal ZrO(2) thin films. The solid state structure of Fe(pybzim)(3)(ClO(4))(2).CH(3)CN.H(2)O was determined by single-crystal X-ray diffraction at 110 K to be triclinic, P-1, a = 11.6873(18), b = 12.2318(12), c = 14.723(4) A, alpha = 89.864(13) degrees , beta = 71.430(17) degrees , gamma = 73.788(11) degrees , V = 1907.1(6) A(3), Z = 2, and R = 0.0491. The iron compound has a meridional FeN(6) distorted octahedral geometry with bond lengths expected for a low-spin iron center at 110 K. The visible absorption spectra of Fe(pybzim)(3)(2+) and Fe(pymbA)(3)(2+), where pymbA is 4-(2-pyridin-2-yl-benzimidazol-1-ylmethyl)-benzoic acid, in methanol solution were dominated by metal-to-ligand charge-transfer (MLCT) bands. Variable-temperature UV-visible absorption spectroscopy revealed dramatic changes in the extinction coefficient consistent with a high-spin ((1)A) left harpoon over right harpoon low-spin ((5)T) equilibrium. Thermodynamic parameters for the temperature-dependent spin equilibrium of Fe(pymbA)(3)(2+) in methanol were determined to be DeltaH(HL) = 3270 +/- 210 cm(-1) and DeltaS(HL) = 13.3 +/- 0.8 cm(-1) K(-1). The corresponding values for Fe(pybzimEE)(3)(2+), where pybzimEE is (2-pyridin-2-yl-benzimidazol-1-yl)-acetic acid ethyl ester, in acetonitrile solution were determined to be 3072 +/- 34 cm(-1)and 10.5 +/- 0.1 cm(-1) K(-1). The temperature-dependent effective magnetic moments of Fe(pybzimEE)(3)(2+) in acetonitrile solution were also quantified by the Evans method. Pulsed 532 nm light excitation of Fe(pybzim)(3)(2+) or Fe(pymbA)(3)(2+) in solution resulted in an immediate bleach of the MLCT absorption bands. Relaxation back to the equilibrium state followed a first-order reaction mechanism. Arrhenius analysis

  11. Enhanced Piezoelectric Energy Harvesting Performance of Flexible PVDF-TrFE Bilayer Films with Graphene Oxide.

    Science.gov (United States)

    Bhavanasi, Venkateswarlu; Kumar, Vipin; Parida, Kaushik; Wang, Jiangxin; Lee, Pooi See

    2016-01-13

    Ferroelectric materials have attracted interest in recent years due to their application in energy harvesting owing to its piezoelectric nature. Ferroelectric polymers are flexible and can sustain larger strains compared to inorganic counterparts, making them attractive for harvesting energy from mechanical vibrations. Herein, we report, for the first time, the enhanced piezoelectric energy harvesting performance of the bilayer films of poled poly(vinylidene fluoride-trifluoroethylene) [PVDF-TrFE] and graphene oxide (GO). The bilayer film exhibits superior energy harvesting performance with a voltage output of 4 V and power output of 4.41 μWcm(-2) compared to poled PVDF-TrFE films alone (voltage output of 1.9 V and power output of 1.77 μWcm(-2)). The enhanced voltage and power output in the presence of GO film is due to the combined effect of electrostatic contribution from graphene oxide, residual tensile stress, enhanced Young's modulus of the bilayer films, and the presence of space charge at the interface of the PVDF-TrFE and GO films, arising from the uncompensated polarization of PVDF-TrFE. Higher Young's modulus and dielectric constant of GO led to the efficient transfer of mechanical and electrical energy.

  12. Tuning structural and magnetic properties of Fe films on Si substrates by hydrogenation processing

    Energy Technology Data Exchange (ETDEWEB)

    Sandu, S.G. [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania); Bucharest University, Faculty of Physics, 077125 Bucharest-Magurele (Romania); Palade, P.; Schinteie, G. [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania); Birsan, A. [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania); Bucharest University, Faculty of Physics, 077125 Bucharest-Magurele (Romania); Trupina, L. [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania); Kuncser, V., E-mail: kuncser@infim.ro [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania)

    2014-02-15

    Highlights: • Fe films have been grown on Si(0 0 1) substrates and subsequently hydrogenated. • As deposited films present soft magnetic character and a strong magnetic texture. • Structural and magnetic properties can be tuned via hydrogenation treatments. • Ferromagnetic/semiconductor interfaces might be manipulated via hydrogenation. -- Abstract: In order to study specific phenomena at ferromagnetic/semiconducting interfaces, of potentially high interest in spintronics and information technology, structural aspects and magnetic properties of Fe thin films grown on Si(0 0 1) substrates by RF sputtering have been investigated using {sup 57}Fe conversion electron Mössbauer spectroscopy (CEMS) and magneto-optic Keer effect (MOKE). Films of different thicknesses have been deposited either directly on crystalline Si substrates or on Cu buffer layers. An inherent Fe oxide layer is observed in all as prepared films, with a relative thickness decreasing drastically with the deposition time. The Cu buffer layer does not diminish either the interfacial diffusion or the oxidation process. An efficient method to prepare sharper oxygen- and silicon-free interfaces for an improved spin injection, via thermal treatment in hydrogen atmosphere, is proposed. Accordingly, the hydrogenation treatments are very efficient in the modification of the ferromagnetic film structure, phase composition, magnetic properties and interfacial mixing.

  13. High-pressure crystal structure investigation of synthetic Fe2SiO4 spinel

    DEFF Research Database (Denmark)

    Nestola, F.; Balic Zunic, Tonci; Koch-Müller, M.;

    2011-01-01

    The crystal structure of Fe2SiO4 spinel at room temperature was investigated at seven different pressures by X-ray diffraction, using a diamond anvil cell to examine the influence of Fe substitution on ringwoodite behaviour at high pressure. The results compared with those of a pure Mg endmember...... show that the substitution of Fe into the spinel structure causes only small changes in the compression rate of coordination polyhedra and the distortion of the octahedron. The data show that the compression rate for the octahedron and tetrahedron in (Mg,Fe)2SiO4 can be considered statistically equal...... for FeO6 and MgO6, as well as for SiO4 in both the endmembers. This shows why almost identical bulk moduli are reported along the solid solution in recent literature....

  14. Fe-Zr-Nd-Y-B permanent magnet derived from crystallization of bulk amorphous alloy

    Science.gov (United States)

    Tan, Xiaohua; Xu, Hui; Bai, Qin; Dong, Yuanda

    2007-12-01

    The microstructure and magnetic properties of Nd2Fe14B/(Fe3B,α-Fe) nanocomposite magnet derived form crystallization of bulk amorphous Fe68Zr2Y4B21Nd5 alloy, which was prepared by copper mold casting, have been investigated. The obtaining maximum values of Ms, Mr, Hci, and (BH)max annealed at 963K for Fe68Zr2Nd5Y4B21 alloy are 86Am2/kg, 49Am2/kg, 380kA/m, and 43kJ/m3, respectively. δM plot, high resolution transmission electron microscopy observation, and three-dimensional atom probe technique clarified that the hard magnetic behavior is due to the exchange coupling between soft and hard magnetic nanophases.

  15. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Science.gov (United States)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.

  16. Magnetoelectric coupling effect in transition metal modified polycrystalline BiFeO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sreenivas Puli, Venkata, E-mail: pvsri123@gmail.com [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118 (United States); Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936 (United States); Kumar Pradhan, Dhiren [Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936 (United States); Gollapudi, Sreenivasulu [Department of Physics, Oakland University, Rochester, MI 48309-4401 (United States); Coondoo, Indrani [Department of Materials and Ceramic and CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Panwar, Neeraj [Department of Physics, Central University of Rajasthan, Bandar Sindri, Kishangarh 305801, Rajasthan (India); Adireddy, Shiva; Chrisey, Douglas B. [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118 (United States); Katiyar, Ram S. [Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936 (United States)

    2014-11-15

    Rare-earth (Sm) and transition metal (Co) modified polycrystalline BiFeO{sub 3} (BFO) thin films have been deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrate successfully through pulsed laser deposition (PLD) technique. Piezoelectric, leakage current and temperature dependent dielectric and magnetic behaviour were investigated for the films. Typical “butterfly-shaped” loop were observed in BSFCO films with an effective piezoelectric constant (d{sub 33}) ∼94 pm/V at 0.6 MV/cm. High dielectric constant ∼900 and low dielectric loss ∼0.25 were observed at room temperature. M–H loops have shown relatively high saturation magnetization ∼35 emu/cm{sup 3} at a maximum field of H ∼20 kOe. Enhanced magnetoelectric coupling response is observed under applied magnetic field. The multiferroic, piezoelectric, leakage current behaviours were explored. Such studies should be helpful in designing multiferroic materials based on BSFCO films. - Highlights: • Transition metal modified polycrystalline BiFeO{sub 3} thin films prepared using PLD. • High ME-coupling response was observed in co-substituted BiFeO{sub 3} thin films. • High magnetization ∼35 emu/cm{sup 3} at a maximum field of H ∼20 kOe. • Low leakage current might be due to co-substitution in BiFeO{sub 3} thin films. • A notable piezoelectric constant d{sub 33} ∼94 pm/V was found in BiFeO{sub 3} thin films.

  17. Fabrication and properties of SmFe2-PZT magnetoelectric thin films

    KAUST Repository

    Giouroudi, Ioanna

    2013-05-17

    Magnetoelectric (ME) thin film composites are attracting a continually increasing interest due to their unique features and potential applications in multifunctional microdevices and integrated units such as sensors, actuators and energy harvesting modules. By combining piezoelectric and highly magnetostrictive thin films, the potentialities of these materials increase. In this paper we report the fabrication of SmFe2 and PZT thin films and the investigation of their properties. First of all, a ~ 400 nm thin SmFe film was deposited on top of Si/SiO2 substrate by magnetron sputter deposition. Afterwards, a 140 nm Pt bottom electrode was sputtered on top of the SmFe film forming a bottom electrode. Spin coating was employed for the deposition of the 150 nm thin PZT layer. A PZT solution with 10 %Pb excess was utilized for this fabrication step. Finally, circular Pt top electrodes were sputtered as top electrodes. This paper focuses on the microstructure of the individual films characterized by X-Ray diffractometer (XRD) and scanning electron microscopy (SEM). A piezoelectric evaluation system, aixPES, with TF2000E analyzer component was used for the electric hysteresis measurements of PZT thin films and a vibrating sample magnetometer (VSM) was employed for the magnetic characterization of the SmFe. The developed thin films and the fabricated double layer SmFe-PZT exhibit both good ferromagnetic and piezoelectric responses which predict a promising ME composite structure. The quantitative chemical composition of the samples was confirmed by energy dispersive spectroscopy (EDX). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  18. Fabrication of pyrite FeS{sub 2} thin films by sulfurizing oxide precursor films deposited via successive ionic layer adsorption and reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Kaiwen; Su, Zhenghua; Yang, Jia; Han, Zili [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Liu, Fangyang, E-mail: liufangyang@csu.edu.cn [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney 2052 (Australia); Lai, Yanqing; Li, Jie [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Engineering Research Center of High Performance Battery Materials and Devices, Research Institute of Central South University in Shenzhen, Shenzhen 518057 (China); Liu, Yexiang [School of Metallurgy and Environment, Central South University, Changsha 410083 (China)

    2013-09-02

    Iron pyrite (FeS{sub 2}) is a naturally abundant and nontoxic semiconductor that can potentially be used in photovoltaic devices. In this report, pure pyrite FeS{sub 2} thin films with homogeneous morphology and ideal composition are fabricated by sulfurizing Fe{sub 2}O{sub 3} precursor thin films deposited via successive ionic layer adsorption and reaction method. The formation mechanism of FeS{sub 2} is identified by X-ray photoelectron spectroscopy. The optical and electrical (including photoelectrochemical) measurements show that the prepared pyrite FeS{sub 2} thin films have high absorption coefficient, suitable band gap, p-type conductivity and good photo-electrical conversion ability. - Highlights: • FeS{sub 2} films were prepared based on successive ionic layer adsorption and reaction method. • XPS analysis revealed the formation mechanism of FeS{sub 2} films. • The FeS{sub 2} thin films are of pure pyrite structure and p-type conductivity. • The FeS{sub 2} thin films have suitable optical and electrical properties for solar cells.

  19. 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.

  20. Hydrodynamic interactions in freely suspended liquid crystal films

    Science.gov (United States)

    Kuriabova, Tatiana; Powers, Thomas R.; Qi, Zhiyuan; Goldfain, Aaron; Park, Cheol Soo; Glaser, Matthew A.; Maclennan, Joseph E.; Clark, Noel A.

    2016-11-01

    Hydrodynamic interactions play an important role in biological processes in cellular membranes, a large separation of length scales often allowing such membranes to be treated as continuous, two-dimensional (2D) fluids. We study experimentally and theoretically the hydrodynamic interaction of pairs of inclusions in two-dimensional, fluid smectic liquid crystal films suspended in air. Such smectic membranes are ideal systems for performing controlled experiments as they are mechanically stable, of highly uniform structure, and have well-defined, variable thickness, enabling experimental investigation of the crossover from 2D to 3D hydrodynamics. Our theoretical model generalizes the Levine-MacKintosh theory of point-force response functions and uses a boundary-element approach to calculate the mobility matrix for inclusions of finite extent. We describe in detail the theoretical and computational approach previously outlined in Z. Qi et al., Phys. Rev. Lett. 113, 128304 (2014), 10.1103/PhysRevLett.113.128304 and extend the method to study the mutual mobilities of inclusions with asymmetric shapes. The model predicts well the observed mutual mobilities of pairs of circular inclusions in films and the self-mobility of a circular inclusion in the vicinity of a linear boundary.

  1. Epitaxial Cu(001) films grown on a Cr/Ag/Fe/GaAs(001) buffer system

    Energy Technology Data Exchange (ETDEWEB)

    Gottlob, Daniel M., E-mail: d.gottlob@fz-juelich.de [Peter Grünberg Institut, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich (Germany); Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universität Duisburg-Essen, 47048 Duisburg (Germany); Jansen, Thomas [Peter Grünberg Institut, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich (Germany); Jülich-Aachen Research Alliance, Fundamentals for Future Information Technology (JARA-FIT), Forschungszentrum Jülich, 52425 Jülich (Germany); Hoppe, Michael [Peter Grünberg Institut, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich (Germany); Bürgler, Daniel E. [Peter Grünberg Institut, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich (Germany); Jülich-Aachen Research Alliance, Fundamentals for Future Information Technology (JARA-FIT), Forschungszentrum Jülich, 52425 Jülich (Germany); and others

    2014-07-01

    We present a procedure to prepare single-crystalline, high-purity Cu(001) films (templates) suitable as substrates for subsequent epitaxial thin-film growth. The template films were grown in a dedicated molecular-beam epitaxy system on a Cr/Ag/Fe/GaAs(001) buffer layer system. Low-energy electron diffraction and X-ray diffraction were applied to determine the surface orientation and the epitaxial relationship between all layers of the stack. Post-annealing at moderate temperatures enhances the quality of the film as shown by low-energy electron diffraction and atomic force microscopy. X-ray photoemission and Auger electron spectroscopy confirm that no atoms of the buffer layers diffuse into the Cu film during the initial preparation and the post-annealing treatment. The completed Cu(001) template system can be exposed to air and afterwards refurbished by Ar{sup +}-ion bombardment and annealing, enabling the transfer between vacuum systems. The procedure provides suitable conductive thin film templates for studies of epitaxial thin films, e.g. on the magnetic and magnetotransport properties of Co and Ni based films and multilayers. - Highlights: • Preparation of epitaxial Cu(001) template films on an insulating substrate • Characterization of template structure, orientation, cleanness, and roughness • Template films can be exposed to air and refurbished in different vacuum system. • Template films are suitable for further thin film growth at up to 570 K.

  2. Structural and magnetic characteristics of FeCo thin films modified by combinatorial ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Groudeva-Zotova, S. [Combinatorial Materials Science Group- Research Center CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany); Karl, H. [Institute of Physics, University of Augsburg, 86135 Augsburg (Germany); Savan, A. [Combinatorial Materials Science Group- Research Center CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany); Feydt, J. [Combinatorial Materials Science Group- Research Center CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany); Wehner, B. [Combinatorial Materials Science Group- Research Center CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany); Walther, T. [Combinatorial Materials Science Group- Research Center CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany); Zotov, N. [Combinatorial Materials Science Group- Research Center CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany)]. E-mail: zotov@caesar.de; Stritzker, B. [Institute of Physics, University of Augsburg, 86135 Augsburg (Germany); Ludwig, A. [Combinatorial Materials Science Group- Research Center CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany); Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University, 44780 Bochum (Germany)

    2006-01-20

    This work presents results on modifications of the structure and the magnetic properties of magnetron-sputtered Fe{sub 5}Co{sub 5} films induced by high dose Sm or Xe ion implantation. A combinatorial approach was used in order to screen a wide range of implantation doses from 4 x 10{sup 15} to 1.6 x 10{sup 17} ions/cm{sup 2}. Sm-implanted FeCo films are considered as precursors for the synthesis of multi-phase exchange-spring magnetic materials while Xe ion implantation of such films is known as a method to modify film stresses and magnetic properties. Materials libraries of as-implanted films were investigated by energy dispersive X-ray analysis (EDX) and secondary ion mass spectrometry (SIMS) for the film composition and concentration depth profiles, transmission electron microscopy (TEM) and X-ray diffraction (XRD) for the film morphology and crystalline structure, vibrating sample magnetometry (VSM) for the magnetization behaviour and four-point probe measurements for the film resistivity. Three main results were found on the basis of this combinatorial study: (i) The high-dose Sm-implanted samples have an overall Sm concentration above the value necessary for Sm-Fe(Co) alloy formation and show magnetic hysteresis curves corresponding to two-phase or two-layer film structure; (ii) The two implanted series show quite different magnetic anisotropy in the film plane - a negligible one for Xe and a strong one for Sm implantation; (iii) For the Sm-implanted samples a clear local maxima in the coercivity H{sub c} and the anisotropy field H {sub k} can be seen at D {sub Sm} {>=} 1 x 10{sup 16} ions/cm{sup 2}. The XRD spectra of the libraries show that the last two effects are closely related to the film strains introduced by the implantation process.

  3. Analysis of thin-film photonic crystal microstructures

    CERN Document Server

    Pottage, J M

    2003-01-01

    Optical-scale microstructures containing thin-film photonic crystals (TFPCs) are modelled by transfer/scattering matrix methods, based on Fourier-series expansion of the optical Bloch eigenmodes. The majority of the TFPCs considered consist of 2D arrays of holes arranged in a triangular lattice, etched into high-index Al sub x Ga sub 1 sub - sub x As and placed on a low-index oxidised substrate. These TFPCs can be easily fabricated by standard electron-beam lithography techniques. Unlike most photonic crystal devices that have been proposed, our 'intra-pass-band' TFPCs would work by exploiting the somewhat surprising properties of propagating optical Bloch waves rather than directly relying on photonic bandgaps. By numerical modelling, it is demonstrated that 2D-patterned TFPCs can support highly dispersive high-Q quasi-guided and truly-guided resonant modes, and the unusual properties of these modes are explained in terms of their Bloch-wave compositions. Modal dispersion diagrams of TFPCs, showing the loci ...

  4. Microstructure and conduction behavior of BiFeO3 thin film deposited on Ge-doped ZnO

    Science.gov (United States)

    Raghavan, Chinnambedu Murugesan; Choi, Ji Ya; Kim, Sang Su

    2017-02-01

    BiFeO3 (BFO) thin films were deposited on a Ge-doped ZnO (GZO)/Si(100) and a Pt(111)/Ti/SiO2/Si(100) using a pulsed laser deposition technique. An improved crystal growth property was observed for the BFO thin film deposited on the GZO/Si(100). The BFO thin film, which was deposited on the (00 l) textured GZO/Si(100), exhibited preferred ( l00) orientated grains, while randomly orientated grains were observed for the thin film deposited on the Pt(111)/Ti/SiO2/Si(100). When compared with the Pt/BFO/Pt capacitor, the GZO/BFO/GZO capacitor exhibited improved conduction behaviors, such as a low leakage current density and high stability against electrical breakdown. From the J-E curves, conduction of the GZO/BFO/GZO and the Pt/BFO/Pt capacitors was found to be dominated by Ohmic and space charge limited conductions at low and high electric field, respectively.

  5. Vectorial magnetometry and anisotropy studies on thin Co{sub 50}Fe{sub 50} films using MOKE

    Energy Technology Data Exchange (ETDEWEB)

    Kuschel, Timo; Wollschlaeger, Joachim [Fachbereich Physik, Universitaet Osnabrueck, Barbarastr. 7, 49069 Osnabrueck (Germany); Hamrle, Jaroslav; Pistora, Jaromir [Department of Physics, VSB - Technical University of Ostrava, 17. listopadu 15, 70833 Ostrava-Poruba (Czech Republic); Bosu, Subrojati; Sakuraba, Yuya; Takanashi, Koki [Institute for Materials Research (IMR), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan)

    2011-07-01

    Magnetooptical Kerr effect (MOKE) is a powerful tool to determine magnetic properties of thin magnetic films. In some cases this technique is only applied to detect magnetization curves qualitatively. In order to perform a quantitative analysis we present MOKE measurements with s- and p-polarized incident light, using an external magnetic field either parallel or perpendicular to the plane of incidence of light and different orientations of the crystalline substrate. The processing of the data includes vectorial magnetometry as well as studies of the anisotropy constants and magnetic axes. The investigated Co{sub 50}Fe{sub 50} films o f 50 nm thickness on MgO(001) are prepared with different annealing temperatures (RT up to 400 C). On the one hand the films with lower annealing tempe ratures show typical magnetic reversal processes of samples with four-fold symmetry as expected for cubic crystal structures. On the other hand the film annealed at 400 C presents an additional strong in-plane anisotropy, which is discussed in context of a classical free energy approach.

  6. Molecular Beam Epitaxy Growth of Superconducting Ba1-xKxFe2As2 and SmFeAs(O,F) Films

    Science.gov (United States)

    Ueda, Shinya; Takeda, Soichiro; Takano, Shiro; Mitsuda, Akihiro; Naito, Michio

    2012-01-01

    We report the molecular beam epitaxy (MBE) growth of the iron-based superconductors, Ba1-xKxFe2As2 and SmFeAs(O,F). In the growth of Ba1-xKxFe2As2 films, the key to incorporating volatile K in films is low-temperature (≤350 °C) growth in reduced As flux. The highest Tc thus far obtained is Tcon (Tcend) = 38.0 K (35.8 K). In the growth of superconducting SmFeAs(O,F), we adopted two methods. In the first method, we first grew pristine SmFeAsO films, and subsequently introduced F into the films by diffusion from an overlayer of SmF3. In the second method, we grew as-grown superconducting SmFeAs(O,F) films by coevaporating Sm, SmF3, Fe, and As. Thus far, better results have been obtained by the first F diffusion method. The films prepared by F diffusion showed Tcon (Tcend) = 56.5 K (55.3 K), whereas the as-grown films showed Tcon (Tcend) = 51.5 K (48.0 K).

  7. Iron atoms redistribution in oxide films of Zr-Fe, Zr-Fe-Cu alloys during corrosion in autoclave at 350°C

    Science.gov (United States)

    Filippov, V.; Bateev, A.

    2016-04-01

    The data on changes of iron atoms state in the oxide films of binary Zr-1.24 mas.%Fe and ternary Zr-1.39 mas.%Fe-0.60 mas.%Cu zirconium alloys are obtained. Alloys are subjected to corrosion tests under autoclave conditions at 350°C temperature in a steam-water environment under pressure p = 16.8 MPa. In initial specimens of the alloys the iron atoms are in the form of intermetallic compounds. In oxide films the decomposition of intermetallic compounds and formation of new compounds occurs with structural phase distortion. In the oxide films metallic the metallic iron particles α-Fe, iron oxide in the form of hematite α-Fe2O3, solid solutions of iron ions in ZrO2 are formed. The phase composition of the oxide films depends on the alloy composition and changes during the growth process of the oxide film.

  8. Structural and Magnetic Properties of FePt-C Nanocomposite Films

    Institute of Scientific and Technical Information of China (English)

    WANG Hao; YANG Fu-Jun; CHEN Kan-Song; ZHOU Bin; ZHANG Yuan-Wei; GU Hao-Shuang; CHIAH M. F.; CHEUNG W. Y.; WONG S. P.

    2004-01-01

    @@ Nanocomposite FePt-C thin films were prepared by a pulsed filtered vacuum arc deposition technique. The films were characterized by non-Rutherford backscattering spectrometry, x-ray diffraction, and magnetic force microscopy. The dependence of magnetic properties against annealing temperature was studied by using a vibrating sample magnetometer. Both x-ray diffraction and magnetic force microscopy analyses confirmed the formation of nano-crystallites of face-centred-tetragonal phase of FePt in the carbon matrix after annealing at a sufficiently high temperature. For the film with a composition of (Fe0.55Pt0.45)0.78C0.22, the coercivity and the grain size were observed to increase with increasing annealing temperature, up to a value of 3.5 kOe at an annealing temperature of 650℃, and with a grain size about 10. 5 nm.

  9. Scaling of Anomalous Hall Effects in Facing-Target Reactively Sputtered Fe4N Films

    KAUST Repository

    Zhang, Yan

    2015-05-13

    Anomalous Hall effect (AHE) in the reactively sputtered epitaxial and polycrystalline γ′-Fe4N films is investigated systematically. The Hall resistivity is positive in the entire temperature range. The magnetization, carrier density and grain boundaries scattering have a major impact on the AHE scaling law. The scaling exponent γ in the conventional scaling of is larger than 2 in both the epitaxial and polycrystalline γ′-Fe4N films. Although γ>2 has been found in heterogeneous systems due to the effects of the surface and interface scattering on AHE, γ>2 is not expected in homogenous epitaxial systems. We demonstrated that γ>2 results from residual resistivity (ρxx0) in γ′-Fe4N films. Furthermore, the side-jump and intrinsic mechanisms are dominant in both epitaxial and polycrystalline samples according to the proper scaling relation.

  10. Epitaxial ferroelectric BiFeO{sub 3} thin films for unassisted photocatalytic water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Wei [Institute of Materials Research and Engineering (IMRE), A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Kent Ridge, Singapore 119260 (Singapore); Yao, Kui; Lim, Yee-Fun; Suwardi, Ady [Institute of Materials Research and Engineering (IMRE), A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Liang, Yung C. [Department of Electrical and Computer Engineering, National University of Singapore, Kent Ridge, Singapore 119260 (Singapore)

    2013-08-05

    Considering energy band alignment and polarization effect, ferroelectric BiFeO{sub 3} thin films are proposed as the photoanode in a monolithic cell to achieve unassisted photocatalytic water splitting. Significant anodic photocurrent was observed in our epitaxial ferroelectric BiFeO{sub 3} films prepared from sputter deposition. Both negative polarization charges and thinner films were found to promote the anodic photocatalytic reaction. Ultraviolet photoelectron spectroscopy proved that the conduction and valence band edges of BiFeO{sub 3} straddle the water redox levels. Theoretical analyses show that the large switchable polarization can modify the surface properties to promote the hydrogen and oxygen evolutions on the surfaces with positive and negative polarization charges, respectively.

  11. Epitaxial ferroelectric BiFeO3 thin films for unassisted photocatalytic water splitting

    Science.gov (United States)

    Ji, Wei; Yao, Kui; Lim, Yee-Fun; Liang, Yung C.; Suwardi, Ady

    2013-08-01

    Considering energy band alignment and polarization effect, ferroelectric BiFeO3 thin films are proposed as the photoanode in a monolithic cell to achieve unassisted photocatalytic water splitting. Significant anodic photocurrent was observed in our epitaxial ferroelectric BiFeO3 films prepared from sputter deposition. Both negative polarization charges and thinner films were found to promote the anodic photocatalytic reaction. Ultraviolet photoelectron spectroscopy proved that the conduction and valence band edges of BiFeO3 straddle the water redox levels. Theoretical analyses show that the large switchable polarization can modify the surface properties to promote the hydrogen and oxygen evolutions on the surfaces with positive and negative polarization charges, respectively.

  12. Composition-Controlled Low Field Magnetostriction of TbFe Amorphous Films

    Institute of Scientific and Technical Information of China (English)

    JIANG Hong-Chuan; ZHANG Wan-Li; ZHANG Wen-Xu; PENG Bin

    2008-01-01

    @@ Amorphous TbFe films are fabricated by dc magnetron sputtering, and their magnetostrictions at low field are examined over a wide range of terbium content (from 32at.% to 70at.%). It is found that the terbium content plays an important role in the magnetic and magnetostrictive properties of TbFe films. TbFe film soft magnetic properties and low field magnetostriction can be efficiently improved by controlling the terbium at an optimum content. The magnetostriction at lower magnetic field is increased with the increase of terbium content up to 48.2at.%. After reaching the maximum value, further increase of terbium content would result in a great decrease of the low field magnetostriction. By contrast, at higher magnetic field, the magnetostriction is decreased monotonically with the increase of the terbium content.

  13. Micromagnetic simulation of ferrimagnetic TbFeCo films with exchange coupled nanophases

    Science.gov (United States)

    Ma, Chung T.; Li, Xiaopu; Poon, S. Joseph

    2016-11-01

    Amorphous ferrimagnetic TbFeCo thin films are found to exhibit exchange bias effect near the compensation temperature by magnetic hysteresis loop measurement. The observed exchange anisotropy is believed to originate from the exchange interaction between the two nanoscale amorphous phases distributed within the films. Here, we present a computational model of phase-separated TbFeCo using micromagnetic simulation. Two types of cells with different Tb concentration are distributed within the simulated space to obtain a heterogeneous structure consisting of two nanoscale amorphous phases. Each cell contains separated Tb and FeCo components, forming two antiferromagnetically coupled sublattices. Using this model, we are able to show the existence of exchange bias effect, and the shift in hysteresis loops is in agreement with experiment. The micromagnetic model developed herein for a heterogeneous magnetic material may also account for some recent measurements of exchange bias effect in crystalline films.

  14. X-Ray Magnetic Circular Dichroism Measurement of Fe-Co Alloy Films Prepared by Electrodeposition

    Institute of Scientific and Technical Information of China (English)

    LI Zong-Mu; XU Fa-Qiang; WANG Li-Wu; WANG Jie; ZHU Jun-Fa; ZHANG Wen-Hua

    2007-01-01

    The macro- and micro-magnetic properties of Fe-Co alloy films eletrodeposited on GaAs(100) are studied by synchrotron radiation x-ray magnetic circular dichroism (XMCD) in combination with the magneto-optical Kerr effect (MOKE) measurements and magnetic force microscopy (MFM). The orbital and spin magnetic moments of each element in the Fe-Co alloy are determined by the sum rules of XMCD. Element-specific hysteresis loops (ESHL) are obtained by recording the La MCD signals as a function of applied magnetic field. MOKE results reveal that the amorphous films are magnetically isotropic in the surface plane. The MFM image shows that the dimension of the magnetic domains is about 1-2 μm, which is much larger than that of the grains, indicating that there are intergranular correlations among these grains. Both ESHL and MOKE hysteresis loops indicate the strong ferromagnetic coupling of Fe and Co in the alloy films.

  15. First-principles study of FeSe epitaxial films on SrTiO3

    Institute of Scientific and Technical Information of China (English)

    刘凯; 高淼; 卢仲毅; 向涛

    2015-01-01

    The discovery of high temperature superconductivity in FeSe films on SrTiO3 substrate has inspired great experimen-tal and theoretical interests. First-principles density functional theory calculations, which have played an important role in the study of bulk iron-based superconductors, also participate in the investigation of interfacial superconductivity. In this article, we review the calculation results on the electronic and magnetic structures of FeSe epitaxial films, emphasiz-ing on the interplay between different degrees of freedom, such as charge, spin, and lattice vibrations. Furthermore, the comparison between FeSe monolayer and bilayer films on SrTiO3 is discussed.

  16. On crystallization of bisphenol-A polycarbonate thin films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chunhong; Li, Qichao; Mao, Wenfeng; Wang, Peng; He, Chunqing, E-mail: hecq@whu.edu.cn

    2015-10-16

    Crystallization of polycarbonate (PC) films as a function of annealing time has been investigated by various methods. A distinct diffraction peak at 17.56°, a sharp decrease of film thickness, an increase of refractive index and branch-type structures on the surface are found merely for the film after crystallization. Interestingly, positron annihilation parameters demonstrate fractional free-volumes in PC films vary significantly not only before crystallization but also at the early stage of annealing, which are not found by other methods. The results show that free-volumes in PC film must be increased remarkably before crystallization, which enables the occurrence of molecule rearrangement. - Highlights: • Fractional free-volume in PC film decreased of early stage of annealing. • Crystallization of PC film on Si substrate occurred after annealed for ∼48 hours. • Fractional free-volume in PC film increased remarkably before crystallization. • Positron diffusion length and S parameter revealed the variation of free volumes.

  17. 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.

  18. Passive Fe2+ : ZnSe single-crystal Q switch for 3-mu m lasers

    NARCIS (Netherlands)

    Voronov, AA; Kozlovskii, [No Value; Korostelin, YV; Podmar'kov, YP; Polushkin, VG; Frolov, MP

    Passive Q-switching of 3-mu m lasers with the help of a Fe2+ : ZnSe single crystal is demonstrated. The 6-mJ, 50-ns giant pulses are obtained from a 2.9364-mu m Er : YAG laser by using this passive Q switch.

  19. The Formation of Crystal Defects in a Fe-Mn-Si Alloy Under Cyclic Martensitic Transformations.

    Science.gov (United States)

    Bondar, Vladimir I; Danilchenko, Vitaliy E; Iakovlev, Viktor E

    2016-12-01

    Formation of crystalline defects due to cyclic martensitic transformations (CMT) in the iron-manganese Fe-18 wt.% Mn-2 wt.% Si alloy was investigated using X-ray diffractometry. Conditions for accumulation of fragment sub-boundaries with low-angle misorientations and chaotic stacking faults in crystal lattice of austenite and ε-martensite were analyzed.

  20. Synthesis of large FeSe superconductor crystals via ion release/introduction and property characterization

    Institute of Scientific and Technical Information of China (English)

    苑冬娜; 董晓莉; 周放; 黄裕龙; 倪顺利; 周花雪; 毛义元; 胡卫; 袁洁; 金魁; 张广铭

    2016-01-01

    Large superconducting FeSe crystals of (001) orientation have been prepared via a hydrothermal ion re-lease/introduction route for the first time. The hydrothermally derived FeSe crystals are up to 10 mm×5 mm×0.3 mm in dimension. The pure tetragonal FeSe phase has been confirmed by x-ray diffraction (XRD) and the composition de-termined by both inductively coupled plasma atomic emission spectroscopy (ICP-AES) and energy dispersive x-ray spec-troscopy (EDX). The superconducting transition of the FeSe samples has been characterized by magnetic and transport measurements. The zero-temperature upper critical field Hc2 is calculated to be 13.2–16.7 T from a two-band model. The normal-state cooperative paramagnetism is found to be predominated by strong spin frustrations below the characteris-tic temperature Tsn, where the Ising spin nematicity has been discerned in the FeSe superconductor crystals as reported elsewhere.

  1. Effect of Co addition on crystallization and magnetic properties of FeSiBPCu alloy

    Directory of Open Access Journals (Sweden)

    Rui Xiang

    2014-12-01

    Full Text Available The effects of Co addition on the microstructure, crystallization processes and soft magnetic properties of (Fe1−xCox83Si4B8P4Cu1 (x=0.35, 0.5, 0.65 alloys were investigated. The experimental results demonstrated that the addition of Co decreased the thermal stability against crystallization of the amorphous phase, and thus improved the heat treatment temperature of this alloy. FeCoSiBPCu nanocrystalline alloys with a dispersed α′-FeCo phase were obtained by appropriately annealing the as-quenched ribbons at 763 K for 10 min. The α′-FeCo with grains size ranging from 9 to 28 nm was identified in primary crystallization. The coercivity (Hc markedly increased with increasing x and exhibited a minimum value at x=0.35, while the saturation magnetic flux density (Bs shows a slight decrease. The (Fe0.65Co0.3583Si4B8P4Cu1 nanocrystalline alloy exhibited a high saturation magnetic flux density Bs of 1.68 T, a low coercivity, Hc of 5.4 A/m and a high effective permeability µe of 29,000 at 1 kHz.

  2. Influence of the rare earth concentration on the crystallization process of Fe-Dy-B amorphous alloys. Study of Fe74Dy6B20 and Fe70Dy10B20 alloys

    Science.gov (United States)

    Ravach, G.; Machizaud, F.; Teillet, J.; LeBreton, J. M.; Fnidiki, A.

    2000-04-01

    The crystallization behaviour of Fe74 Dy6 B20 and Fe70 Dy10 B20 amorphous alloys was carefully investigated by differential scanning calorimetry, Mössbauer spectrometry and x-ray diffraction up to 800 °C. Calorimetric studies were performed in limited temperature ranges that were progressively extended. For Fe74 Dy6 B20 , after partial crystallization into the tetragonal Fe3 B compound, the remaining amorphous part segregates into two amorphous `phases', respectively enriched and impoverished in dysprosium. Tetragonal Fe3 B further transforms into orthorhombic Fe3 B. Metastable Dy3 Fe62 B14 compound then forms from the Dy-impoverished amorphous fraction, and subsequent crystallization of the Dy1 + icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/> Fe4 B4 phase occurs in the Dy-enriched fraction. Finally, Dy3 Fe62 B14 decomposes into bcc iron, Dy1 + icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/> Fe4 B4 and iron borides. The nature of the first crystallization product suggests the existence of local environments of t-Fe3 B type for this Dy concentration. The crystallization process of Fe70 Dy10 B20 strongly differs from that of Fe74 Dy6 B20 . Segregation phenomena occur in the amorphous state prior to any crystallization. If the nature of the first crystallization product is assumed to be correlated with short-range order in the amorphous state, our results suggest that the local environments differ from those of Fe74 Dy6 B20 , as they probably involve dysprosium atoms. This behaviour would agree with a previous Mössbauer study performed on the as-quenched amorphous alloys, providing evidence for a structural modification of the iron environments in the rare earth concentration range 8-9 at.%.

  3. Crystallization and Transport Properties of Amorphous Cr-Si Thin Film Thermoelectrics

    Science.gov (United States)

    Novikov, S. V.; Burkov, A. T.; Schumann, J.

    2014-06-01

    We studied the thermoelectric properties, crystallization, and stability of amorphous and nanocrystalline states in Cr-Si composite films. Amorphous films, prepared by magnetron sputtering, were transformed into the nanocrystalline state by annealing with in situ thermopower and electrical resistivity measurements. We have found that the amorphous state is stable in these film composites to about 550 K. Prior to crystallization, the amorphous films undergo a structural relaxation, detected by peculiarities in the temperature dependences of the transport properties, but not visible in x-ray or electron diffraction. The magnitude and temperature dependences of electrical conductivity and thermopower indicate that electron transport in the amorphous films is through extended states. The amorphous films are crystallized at annealing temperatures above 550 K into a nanocrystalline composite with an average grain size of 10-20 nm.

  4. Ozone and nitrogen dioxide gas sensor based on a nanostructured SrTi{sub 0.85}Fe{sub 0.15}O{sub 3} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Luís F. da, E-mail: lfsilva83@gmail.com [LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14800-900 Araraquara, SP (Brazil); Aix Marseille Université, CNRS IM2NP (UMR 7334), FS St Jérôme S152, Marseille 13397 (France); Mastelaro, Valmor R.; Catto, Ariadne C.; Escanhoela, Carlos A. [Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, 13566-590 São Carlos, SP (Brazil); Bernardini, Sandrine [Aix Marseille Université, CNRS IM2NP (UMR 7334), FS St Jérôme S152, Marseille 13397 (France); Zílio, Sérgio C. [Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, 13566-590 São Carlos, SP (Brazil); Longo, Elson [LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14800-900 Araraquara, SP (Brazil); Aguir, Khalifa, E-mail: khalifa.aguir@im2np.fr [Aix Marseille Université, CNRS IM2NP (UMR 7334), FS St Jérôme S152, Marseille 13397 (France)

    2015-07-25

    Highlights: • Nanostructured SrTi{sub 1−x}Fe{sub x}O{sub 3} films were deposited by electron beam evaporation. • XANES spectroscopy revealed an increase of crystallization after heat-treatment. • Annealing treatment contributes improving the gas-sensing performance. • The SrTi{sub 1−x}Fe{sub x}O{sub 3} film exhibited a good sensitivity to oxidizing gases. • The results show that SrTi{sub 1−x}Fe{sub x}O{sub 3} can be considered a potential ozone gas sensor. - Abstract: In this manuscript, we report an investigation into the sensitivity of two oxidizing gases (ozone and nitrogen dioxide) for nanocrystalline SrTi{sub 0.85}Fe{sub 0.15}O{sub 3} thin films deposited by the electron beam physical vapor deposition technique. Annealing treatment at 500 °C enhanced the crystallization and surface roughness of the thin film. Electrical measurements revealed that the thin film was sensitive to oxidizing gases, especially to low ozone gas levels, exhibiting a fast response time, a short recovery time as well as good reproducibility and reversibility. These findings demonstrate the great potential of the SrTi{sub 0.85}Fe{sub 0.15}O{sub 3} compound to be applied as a selective ozone gas sensor.

  5. Temperature Dependence of Magnetic Properties of SmCo/FeCo Multilayer Films

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Sm22Co78/Fe65Co35/Sm22Co78/Fe65Co35 multilayer films were prepared by magnetron sputter ing. The temperature dependence of coercivity (He), remanence (Mr) and reduced remanence (Mr/Ms) has been measured. The coercivity decreases with increasing of temperature. The remanence decreases with increasing the temperature from 26 to 100C, and then increases with continuously increasing the temperature from 100 to 150℃. The reduced remanence increases with increasing the temperature.

  6. Microstructures of metallic film and diamond growth from Fe-Ni-C system

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The microstructures of metallic film surrounding diamond have been systemically studied using the transmission electron microscopy (TEM) and the atom force microscopy (AFM). The film can be divided into three layers (inner layer near diamond, external layer near graphite and middle layer). The graphite cannot be directly transformed into diamond in the film at HTHP; there exists a parallel relationship between (111) of γ-(Fe,Ni) and (110) of Fe3C in the inner layer; the sawtooth-like step morphology found by AFM on the film is similar to that of corresponding diamond surface. A new model for diamond growth at HPHT is proposed from the parallel relationship and sawtooth-like step morphology. It is believed that Fe3C may be a transitional phase in the course of diamond growth, γ-(Fe,Ni) in the inner layer can absorb carbon atom groups with lamella structure from Fe3C, and then the carbon groups stack on growing diamond.

  7. Gilbert damping parameter characterization in perpendicular magnetized Co2FeAl films

    Science.gov (United States)

    Cui, Yishen; Lu, Jiwei; Khodadadi, Behrouz; Schäfer, Sebastian; Mewes, Tim; Wolf, Stuart

    2013-03-01

    Materials with perpendicular magnetic anisotropy(PMA) have gotten extensive recent attention because of their potential application in spintronic devices such as spin transfer torque random access memory (STT-RAM). It was shown that a much lower switching current density(JC) is required to write STT-RAM tunnel junctions with perpendicular magnetic anisotropy ferromagnetic electrodes (p-MTJ). Additionally Heusler alloy Co2FeAl is expected to further reduce JC due to its ultra low Gilbert damping parameter. In our study, Heusler alloy Co2FeAl films were prepared using a Biased Target Ion Beam Deposition (BTIBD) technique. We demonstrated a low Gilbert damping parameter achieved in thick B2-Co2FeAl films. Besides, we achieved an interfacial PMA in ultra thin Co2FeAl films by rapid thermal annealing (RTA) with no external field presented. Annealing conditions were carefully adjusted to maximize the interfacial PMA. However it was noticed that a higher annealing temperature was required for a low damping parameter which to some extent sacrificed the interfacial PMA. We also deposited ultra thin CoFeB films and characterized their damping parameters for comparison. We acknowledge the financial support from DARPA.

  8. Robust Zero-Field Skyrmion Formation in FeGe Epitaxial Thin Films

    Science.gov (United States)

    Gallagher, J. C.; Meng, K. Y.; Brangham, J. T.; Wang, H. L.; Esser, B. D.; McComb, D. W.; Yang, F. Y.

    2017-01-01

    B 20 phase magnetic materials have been of significant interest because they enable magnetic Skyrmions. One major effort in this emerging field is the stabilization of Skyrmions at room temperature and zero magnetic field. We grow phase-pure, high crystalline quality FeGe epitaxial films on Si(111). Hall effect measurements reveal a strong topological Hall effect after subtracting the ordinary and anomalous Hall effects, demonstrating the formation of high density Skyrmions in FeGe films between 5 and 275 K. In particular, a substantial topological Hall effect was observed at a zero magnetic field, showing a robust Skyrmion phase without the need of an external magnetic field.

  9. Characterization of LiFePO4/C Composite Thin Films Using Electrochemical Impedance Spectroscopy

    Science.gov (United States)

    Bajars, G.; Kucinskis, G.; Smits, J.; Kleperis, J.; Lusis, A.

    2012-08-01

    The composite LiFePO4/C thin films were prepared on steel substrate by radio frequency (RF) magnetron sputtering. Electrochemical properties of the obtained thin films were investigated by cyclic voltammetry charge-discharge measurements and electrochemical impedance spectroscopy (EIS). The films annealed at 550 °C exhibited a couple of redox peaks at 3.45 V vs. Li/Li+ characteristic for the electrochemical lithium insertion/extraction in LiFePO4. At low current rate such composite thin film showed a discharge capacity of over 110 mAh g-1. The dependence of charge transfer resistance, double layer capacitance and lithium diffusion coefficients on applied electrode potential were calculated from EIS data. Determined values of lithium diffusion coefficient were in the range from 8.3-10-13 cm2 s1 to 1.2-10-13 cm2 s-1 at 3.4 V and 3.7 V, respectively.

  10. Morphology of superconducting FeSe thin films grown by MBE and RF-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kronenberg, Alexander; Venzmer, Eike; Haaf, Sebastian ten; Jourdan, Martin [Institut fuer Physik, Johannes Gutenberg Universitaet Mainz (Germany); Maletz, Janek [Institut fuer Physik, Johannes Gutenberg Universitaet Mainz (Germany); Leibniz-Institut fuer Festkoerper- und Werkstoffforschung, Dresden (Germany)

    2013-07-01

    Tunneling spectroscopy on planar junctions is the most direct approach for the investigation of superconducting coupling mechanisms. However, it requires smooth interfaces at the tunneling barrier. The morphology of superconducting thin films of FeSe grown by MBE and co-sputtering (RF) from an iron and a selenium target are compared. MBE deposited films show an extreme sensitivity to stoichiometry, deposition temperature and choice of substrate. These films exhibit macroscopic crevices and a pronounced roughness, rendering the preparation of tunneling junctions impossible. However, sputter deposited epitaxial FeSe thin films clearly show a more favorable morphology. Optical microscopy, AFM and SEM demonstrate a smooth surface with segregations which are eliminated by proper choice of the deposition parameters.

  11. Investigation of magnetic properties in thick CoFeB alloy films for controllable anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ke; Huang, Ya; Chen, Ruofei; Xu, Zhan [Huaqiao University, College of Information Science and Engineering, Xiamen City (China)

    2016-02-15

    CoFeB alloy material has attracted interest for its wide uses in magnetic memory devices and sensors. We investigate magnetic properties of thick Co{sub 40}Fe{sub 40}B{sub 20} films in the thickness range from 10 to 100 nm sandwiched by MgO and Ta layers. Strong in-plane uniaxial magnetic anisotropy is revealed in the as-deposited amorphous films by angular dependent magnetic measurements, and the growth-induced anisotropy is found to strongly depend on the film thickness. A fourfold cubic magnetic anisotropy develops with annealing, as a result of improved crystalline structure in films confirmed by X-ray diffraction measurements. The observed magnetic properties can be explained by the superposition of the uniaxial and additional cubic magnetic anisotropy, tuned by annealing temperature. (orig.)

  12. Investigation of magnetic properties in thick CoFeB alloy films for controllable anisotropy

    Science.gov (United States)

    Wang, Ke; Huang, Ya; Chen, Ruofei; Xu, Zhan

    2016-02-01

    CoFeB alloy material has attracted interest for its wide uses in magnetic memory devices and sensors. We investigate magnetic properties of thick Co40Fe40B20 films in the thickness range from 10 to 100 nm sandwiched by MgO and Ta layers. Strong in-plane uniaxial magnetic anisotropy is revealed in the as-deposited amorphous films by angular dependent magnetic measurements, and the growth-induced anisotropy is found to strongly depend on the film thickness. A fourfold cubic magnetic anisotropy develops with annealing, as a result of improved crystalline structure in films confirmed by X-ray diffraction measurements. The observed magnetic properties can be explained by the superposition of the uniaxial and additional cubic magnetic anisotropy, tuned by annealing temperature.

  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. Al-induced Lateral Crystallization of Amorphous Si Thin Films by Microwave Annealing

    Institute of Scientific and Technical Information of China (English)

    RAO Rui; XU Zhong-yang; ZENG Xiang-bing

    2002-01-01

    Al-induced lateral crystallization of amorphous silicon thin films by microwave annealing is investigated. The crystallized Si films are examined by optical microscopy , Raman spectroscopy, transmission electron microscopy and transmission electron diffraction micrography. After microwave annealing at 480 ℃ for 50 min,the amorphous Si is completely crystallized with large grains of main ( 111 ) orientation. The rate of lateral crystallization is 0.04μm/min. This process, labeled MILC-MA, not only lowers the temperature but also reduces the time of crystallization. The crystallization mechanism during microwave annealing and the electrical properties of polycrystalline Si thin films are analyzed. This MILC-MA process has potential applications in large area electronics.

  15. Electric and Magnetic Properties of Sputter Deposited BiFeO3 Films

    Directory of Open Access Journals (Sweden)

    N. Siadou

    2013-01-01

    Full Text Available Polycrystalline BiFeO3 films have been magnetron sputter deposited at room temperature and subsequently heat-treated ex situ at temperatures between 400 and 700°C. The deposition was done in pure Ar atmosphere, as the use of oxygen-argon mixture was found to lead to nonstoichiometric films due to resputtering effects. At a target-to-substrate distance d=2′′ the BiFeO3 structure can be obtained in larger range process gas pressures (2–7 mTorr but the films do not show a specific texture. At d=6′′ codeposition from BiFeO3 and Bi2O3 has been used. Films sputtered at low rate tend to grow with the (001 texture of the pseudo-cubic BiFeO3 structure. As the film structure does not depend on epitaxy similar results are obtained on different substrates. A result of the volatility of Bi, Bi rich oxide phases occur after heat treatment at high temperatures. A Bi2SiO5 impurity phase forms on the substrate side, and does not affect the properties of the main phase. Despite the deposition on amorphous silicon oxide substrate weak ferromagnetism phenomena and displaced loops have been observed at low temperatures showing that their origin is not strain. Ba, La, Ca, and Sr doping suppress the formation of impurity phases and leakage currents.

  16. Magnetic Properties and Kinetics Parameters of Electroless Magnetic Loss CoFeB Films

    Institute of Scientific and Technical Information of China (English)

    LIU Chang-hui; HE Hua-hui; SHEN Xiang; LI Hai-hua

    2008-01-01

    Electroless CoFeB films with good soft magnetic properties were fabricated on polyester plastic substrate from sodium tartarate as a complexing agent. The plating rate of electroless CoFeB films is a function of concentration of sodium tetrahydroborate, pH of the plating bath, plating temperature and the metallic ratio. The estimated regression coefficient b0-b3 confidence interval, residual error r and confidence interval rint were confirmed by a computer program. The optimal composition of the plating bath was obtained and the dynamic electromagnetic parameters of films were measured in the 2-10 GHz range. At 2 GHz, the μ′, μ″ of the electroless CoFeB films were 304 and 76.6, respectively, as the concentration of reducer is 1 g/L. Magnetic hysteresis loop of the deposited CoFeB films show a remanence close to the saturation magnetization and coercivity of about 55.7-127.4 A/m. The loops along the hard axis display low anisotropic field Hk of 2 388-3 582 A/m.

  17. Observation of uniaxial anisotropy along the [100] direction in crystalline Fe film

    Science.gov (United States)

    Bac, Seul-Ki; Lee, Hakjoon; Lee, Sangyoep; Choi, Seonghoon; Yoo, Taehee; Lee, Sanghoon; Liu, X.; Furdyna, J. K.

    2015-12-01

    We report an observation of uniaxial magnetic anisotropy along the [100] crystallographic direction in crystalline Fe film grown on Ge buffers deposited on a (001) GaAs substrate. As expected, planar Hall resistance (PHR) measurements reveal the presence of four in-plane magnetic easy axes, indicating the dominance of the cubic anisotropy in the film. However, systematic mapping of the PHR hysteresis loops observed during magnetization reversal at different field orientations shows that the easy axes along the and are not equivalent. Such breaking of the cubic symmetry can only be ascribed to the presence of uniaxial anisotropy along the direction of the Fe film. Analysis of the PHR data measured as a function of orientation of the applied magnetic field allowed us to quantify the magnitude of this uniaxial anisotropy field as Oe. Although this value is only 1.5% of cubic anisotropy field, its presence significantly changes the process of magnetization reversal, revealing the important role of the uniaxial anisotropy in Fe films. Breaking of the cubic symmetry in the Fe film deposited on a Ge buffer is surprising, and we discuss possible reason for this unexpected behavior.

  18. Effects of Surface Electron Doping and Substrate on the Superconductivity of Epitaxial FeSe Films.

    Science.gov (United States)

    Zhang, W H; Liu, X; Wen, C H P; Peng, R; Tan, S Y; Xie, B P; Zhang, T; Feng, D L

    2016-03-09

    Superconductivity in FeSe is greatly enhanced in films grown on SrTiO3 substrates, although the mechanism behind remains unclear. Recently, surface potassium (K) doping has also proven able to enhance the superconductivity of FeSe. Here, by using scanning tunneling microscopy, we compare the K doping dependence of the superconductivity in FeSe films grown on two substrates: SrTiO3 (001) and graphitized SiC (0001). For thick films (20 unit cells (UC)), the optimized superconducting (SC) gaps are of similar size (∼9 meV) regardless of the substrate. However, when the thickness is reduced to a few UC, the optimized SC gap is increased up to ∼15 meV for films on SrTiO3, whereas it remains unchanged for films on SiC. This clearly indicates that the FeSe/SrTiO3 interface can further enhance the superconductivity, beyond merely doping electrons. Intriguingly, we found that this interface enhancement decays exponentially as the thickness increases, with a decay length of 2.4 UC, which is much shorter than the length scale for relaxation of the lattice strain, pointing to interfacial electron-phonon coupling as the likely origin.

  19. SPIN-DEPENDENT TUNNELING MAGNETORESISTANCE IN Fe-O/AlOx/Fe-O FILMS

    Institute of Scientific and Technical Information of China (English)

    L.Q. Pan; H. Qiu; F.P. Wang; P. Wu; Y. Tian; S. Luo

    2002-01-01

    Fe-O/AlOx/Fe-O tunnel junctions were prepared by reactive magnetron sputteringunder mixed working gas Ar+2%O2. The insulating AlOx layer of 1-2nm thicknesswas sputtered directly from Al2O3 target. Electrode layers were made of 80at.% ironand 20at.% oxygen. Bottom Fe-O electrode deposited on glass substrate annealedat 473K at the pressure of 3× 10-4Pa for an hour shows disparate crystalline grainstructure, lower electrical resistance and coercivity compared to the as-deposited topelectrode. Only crystalline structrure of α-Fe is observed in both electrodes. Largetunnel magnetoresistance in large Fe-O/AlOx/Fe-O junctions of 1cm2 is observed atroom temperature and the Ⅰ-Ⅴ characteristic curve of the junction shows that thebarrier of the junction is of high quality.

  20. Thermoelectric Properties of Epitaxial β-FeSi2 Thin Films on Si(111) and Approach for Their Enhancement

    Science.gov (United States)

    Taniguchi, Tatsuhiko; Sakane, Shunya; Aoki, Shunsuke; Okuhata, Ryo; Ishibe, Takafumi; Watanabe, Kentaro; Suzuki, Takeyuki; Fujita, Takeshi; Sawano, Kentarou; Nakamura, Yoshiaki

    2016-10-01

    We have investigated the intrinsic thermoelectric properties of epitaxial β-FeSi2 thin films and the impact of phosphorus (P) doping. Epitaxial β-FeSi2 thin films with single phase were grown on Si(111) substrates by two different techniques in an ultrahigh-vacuum molecular beam epitaxy (MBE) system: solid-phase epitaxy (SPE), where iron silicide films formed by codeposition of Fe and Si at room temperature were recrystallized by annealing at 530°C to form epitaxial β-FeSi2 thin films on Si(111) substrates, and MBE of β-FeSi2 thin films on epitaxial β-FeSi2 templates formed on Si(111) by reactive deposition epitaxy (RDE) at 530°C (RDE + MBE). Epitaxial SPE thin films based on codeposition had a flatter surface and more abrupt β-FeSi2/Si(111) interface than epitaxial RDE + MBE thin films. We investigated the intrinsic thermoelectric properties of the epitaxial β-FeSi2 thin films on Si(111), revealing lower thermal conductivity and higher electrical conductivity compared with bulk β-FeSi2. We also investigated the impact of doping on the Seebeck coefficient of bulk and thin-film β-FeSi2. A route to enhance the thermoelectric performance of β-FeSi2 is proposed, based on (1) fabrication of thin-film structures for high electrical conductivity and low thermal conductivity, and (2) proper choice of doping for high Seebeck coefficient.

  1. Microstructure and magnetic behavior of nanosized Fe sub 3 O sub 4 powders and polycrystalline films

    CERN Document Server

    Nedkov, I; Kolev, S; Krezhov, K; Niarchos, D; Moraitakis, E; Kusano, Y; Takada, J

    2002-01-01

    The object of investigation were the magnetic interactions in nanostructured Fe sub 3 O sub 4 assemblies of two kinds (powder and film) where particles of similar size present nearly uniform domains in a close to planar arrangement with spacings sufficient for magnetic interactions. We discuss the use of the soft-chemistry method, i.e. the modified 'ferrite plating' (MFP) technique, for the synthesis of polycrystalline films of magnetite with nanosized crystallites. (author)

  2. 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

  3. 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...

  4. Growth of superconducting SmFeAs(O, F) epitaxial films by F diffusion

    Science.gov (United States)

    Takeda, S.; Ueda, S.; Takano, S.; Yamamoto, A.; Naito, M.

    2012-03-01

    We report on our growth of superconducting SmFeAs(O, F) films by F diffusion. In our process, F-free SmFeAsO films were grown by molecular beam epitaxy (MBE) first, and subsequently F was introduced to the films via F diffusion from an overlayer of SmF3. We compared the growth conditions and also the properties of resultant films for CaF2 and LaAlO3 substrates. The best films on CaF2 exhibited a high transition temperature, {T}_{{c}}^{{on}}~({T}_{{c}}^{{end}})=57.8 K (56.4 K) at the highest, which may exceed the highest Tc ever reported for bulk samples. Furthermore, the films on CaF2 also showed high critical current density over 1 MA cm-2 in self-field at 5 K. On the other hand, the {T}_{{c}}^{{on}}~({T}_{{c}}^{{end}}) of the film on LaAlO3 was 50.3 K (49.3 K). The deteriorated superconducting properties on LaAlO3 appear to be due to oxygen diffusion from LaAlO3 to films.

  5. 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.

  6. Interrelatedness of Fe composition on structural and magnetic properties in Fe-doped SrRuO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Y.Z.; Chmaissem, O.; Kolesnik, S.; Brown, D.E.; Dabrowski, B.; Kimball, C.W. [Northern Illinois University, Institute for NanoScience, Engineering and Technology (INSET), Physics Department, DeKalb, IL (United States); Kim, T.W. [Korea Institute of Industrial Technology, Applied Optics and Energy Research Group, Gwangju (Korea, Republic of); Kim, M.S. [TongMyong University, Department of Information and Communication Engineering, Busan (Korea, Republic of); Genis, A.P. [Northern Illinois University, Institute for NanoScience, Engineering and Technology (INSET), Electrical Engineering Department, DeKalb, IL (United States); Song, J.H. [PaiChai University, Department of Information and Electronic Materials Engineering, Daejeon (Korea, Republic of)

    2014-06-15

    Fe-doping (up to 11 mole%) into SrRuO{sub 3} (SRO) thin films on SrTiO{sub 3} substrates decreased correlation lengths of both surface and interface. It turned out that Fe was doped in the valence state of 3+ without formation of the Fe{sub 2}O{sub 3} phase, which caused orthorhombic distortion. T{sub C} values decreased from 145 K to 97 K with increasing Fe concentration (C{sub Fe}). High magnetic switching fields were observed for all Fe-doped SRO thin films and their strengths showed a linear relationship with C{sub Fe}. Detail structural characterization using synchrotron X-ray diffraction and X-ray photoemission spectroscopy were used to understand its unique magnetic switching field properties. (orig.)

  7. 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.

  8. EFFECT OF ZnFe2O4 DOPING ON THE OPTICALPROPERTIES OF TiO2 THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    李广海; 吴玉程; 张立德

    2001-01-01

    Amorphous TiO2 thin films and ZnFe2O4-doped TiO2 composite films were deposited by radio frequency magnetron sputtering. The effect of ZnFe2O4 doping on the optical properties of TiO2 thin films was reported. Our results show that the absorption edge of TiO2 thin films and composite films exhibits a blueshift with decreasing annealing temperature. The absorption edge of composite films has moved to a visible spectrum range, and a very large redshift occurs in comparison with TiO2 thin films. An enhanced photoluminescence was observed in ZnFe2O4-doped anatase TiO2 thin films at room temperature.

  9. 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.

  10. Preparation and characterization of Co epitaxial thin films on Al2O3(0001) single-crystal substrates

    Science.gov (United States)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki

    2011-01-01

    Co epitaxial thin films were prepared on Al2O3(0001) single-crystal substrates in a substrate temperature range between 50 and 500 °C by ultra high vacuum molecular beam epitaxy. Effects of substrate temperature on the structure and the magnetic properties of the films were investigated. The films grown at temperatures lower than 150 °C consist of fcc- Co(111) crystal. With increasing the substrate temperature, hcp-Co(0001) crystal coexists with the fcc crystal and the volume ratio of hcp to fcc crystal increases. The films prepared at temperatures higher than 250 °C consist primarily of hcp crystal. The film growth seems to follow island-growth mode. The films consisting primarily of hcp crystal show perpendicular magnetic anisotropy. The domain structure and the magnetization properties are influenced by the magnetocrystalline anisotropy and the shape anisotropy caused by the film surface roughness.

  11. Influence of solvent evaporation rate on crystallization of poly(vinylidene fluoride) thin films

    Indian Academy of Sciences (India)

    K Pramod; R B Gangineni

    2015-08-01

    The processes for obtaining crystalline and smooth poly(vinylidene fluoride) (PVDF) thin films using 2-butanone solvent are explored. The in-situ substrate temperature has been systematically controlled to observe the crystallization process. The in-situ substrate temperature is manipulated to control the rate of evaporation of 2-butanone solvent and is found to have played a vital role in the crystallization of PVDF thin films. Further, X-ray diffraction and Raman microscope were utilized to understand the crystalline phase of PDVF thin films, while atomic force microscopy and scanning electron microscopy have been utilized to investigate the surface morphology and surface roughness of the films.

  12. Femtosecond Laser Crystallization of Boron-doped Amorphous Hydrogenated Silicon Films

    Directory of Open Access Journals (Sweden)

    P.D. Rybalko

    2016-10-01

    Full Text Available Crystallization of amorphous hydrogenated silicon films with femtosecond laser pulses is one of the promising ways to produce nanocrystalline silicon for photovoltaics. The structure of laser treated films is the most important factor determining materials' electric and photoelectric properties. In this work we investigated the effect of femtosecond laser irradiation of boron doped amorphous hydrogenated silicon films with different fluences on crystalline volume fraction and electrical properties of this material. A sharp increase of conductivity and essential decrease of activation energy of conductivity temperature dependences accompany the crystallization process. The results obtained are explained by increase of boron doping efficiency in crystalline phase of modified silicon film.

  13. Electrochemical properties of the passive film on bulk Zr-Fe-Cr intermetallic fabricated by spark plasma sintering

    Science.gov (United States)

    Bai, Yakui; Ling, Yunhan; Lai, Wensheng; Xing, Shupei; Ma, Wen

    2016-12-01

    Although Zr-based second phase particles (SPPs) are important factors influencing corrosion resistance of zircaloy cladding materials, the corrosion behavior of SPPs has not been investigated by means of electrochemical method so far. In order to clarify the role of SPPs commonly existed in zircaloy, bulk Zr-based intermetallics were firstly fabricated by spark plasma sintering (SPS) at temperatures 1373 K and an applied pressure of 60 MPa in this work. Both the natural passive film on surface and oxidation behavior of intermetallic has been investigated in this work. X-ray diffraction (XRD) pattern showed that as-prepared intermetallic of crystal structure belongs to Laves phase with AB2 type. Electrochemical measurement of passive film on surface of bulk Zr-based intermetallic exhibited significant difference with that of zirconium. Potentiodynamic measurements results revealed that intermetallic exhibited higher corrosion potential and lower corrosion current density than that of pure zirconium, implying that Zr-based second phase will act as cathode when they are included in zirconium matrix. Meanwhile, significant improvement of Zr-Fe-Cr intermetallic on the water chemistry corrosion resistance was demonstrated comparing with Zr-Fe and Zr-Cr binary intermetallics.

  14. 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.``

  15. Electronic and magnetic structure of GaxFe1-x thin films

    Energy Technology Data Exchange (ETDEWEB)

    Arenholz, E.; van der Laan, G.; McClure, A.; Idzerda, Y.

    2010-09-08

    The electronic as well as magnetic properties of Ga{sub x}Fe{sub 1-x} films were studied by soft x-ray measurements. Using x-ray magnetic circular dichroism the Fe majority-spin band was found to be completely filled for x {approx} 0.3. With further enhanced Ga content, the Fe moment as well as the angular dependence of the x-ray magnetic linear dichroism decrease strongly, which we attribute to the formation of D0{sub 3} precipitates. Moreover, the magnetocrystalline anisotropy drops significantly.

  16. Growth and magnetic properties of epitaxial Fe4N films on insulators possessing lattice spacing close to Si(001) plane

    Science.gov (United States)

    Ito, Keita; Higashikozono, Soma; Takata, Fumiya; Gushi, Toshiki; Toko, Kaoru; Suemasu, Takashi

    2016-12-01

    We grew ferromagnetic Fe4N films by molecular beam epitaxy on MgO(001), MgAl2O4(MAO)(001), SrTiO3(STO)(001), and CaF2(001) substrates, possessing the lattice spacing close to Si(001) plane. Highly oriented epitaxial growth was confirmed for the Fe4N films on the MgO, MAO, and STO by reflection high-energy electron diffraction and x-ray diffractions. The degree of orientation of the Fe4N film on the STO was the best among these samples. This was attributed to the smallest lattice mismatch of -2.8% between Fe4N(001) and STO(001). On the other hand, crystallinity of the Fe4N film on the CaF2(001) substrate was poor due to a very large lattice mismatch of -30% between Fe4N(001) and CaF2(001) arising from the unexpected epitaxial relationship as Fe4N(001)[100] || CaF2(001)[100]. The saturation magnetization of the Fe4N films was approximately 1200 emu/cm3 at room temperature for all the samples, and the magnetization easy axis was in-plane Fe4N[100]. We consider that STO is the suitable buffer layer for the growth of Fe4N on Si(001), hence to realize the Si-based spintronics devices using highly spin-polarized Fe4N.

  17. Pulsed laser deposition of Sr2FeMoO6 thin films grown on spark plasma sintered Sr2MgWO6 substrates

    Science.gov (United States)

    Santosh, M.; Lacotte, M.; David, A.; Boullay, Ph; Grygiel, C.; Pravarthana, D.; Rohrer, G. S.; Salvador, P. A.; Padhan, P.; Lüders, U.; Wang, Junling; Prellier, W.

    2017-06-01

    Sr2FeMoO6 (SFMO) films were deposited on polycrystalline spark plasma synthesized Sr2MgWO6 (SMWO) substrates. Films were grown using pulsed laser deposition at temperatures (T dep) between 720 °C and 820 °C in a vacuum environment of pressure {{P}\\text{dep}}={{10}-6} mbar (0.1 mPa); after deposition they were cooled either in a pressure {{P}\\text{cool}}={{P}\\text{dep}} or {{P}\\text{cool}}={{10}-4} mbar (10 mPa) O2. Despite the use of an isostructural substrate, the growth and cooling conditions play the primary role in determining details of the films’ structures and properties, similarly to single-crystals. Grazing x-ray and electron back-scatter diffraction indicate that vacuum-cooled films were pure perovskite-structured SFMO exhibiting grain-over-grain growth that aligned the perovskite sub-cells. SrMoO4 impurities were observed in the x-ray patterns for the oxygen-cooled films similarly to single-crystal substrates. Magnetic, electronic and magnetoresistive properties were all a function of growth and cooling environments. The Curie temperature and magnetization of the films increased with T dep up to 800 °C. The vacuum-cooled films had low-resistivities with essentially metallic conductivity (small resistivity increases occurred at low-T), while the conductivity of oxygen-cooled films were consistent with variable range hopping. The oxygen-cooled films had higher low-field magnetoresistance effects at 5 K than the vacuum-cooled films, which seems consistent with SrMoO4 forming at grain boundaries. This work opens the route to tailor the electronic properties by engineering the grain boundaries in thin films.

  18. Effect of irradiation temperature on crystallization of {alpha}-Fe induced by He irradiations in Fe{sub 80}B{sub 20} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    San-noo, Toshimasa; Toriyama, Tamotsu; Wakabayashi, Hidehiko; Iijima, Hiroshi [Musashi Inst. of Tech., Tokyo (Japan); Hayashi, Nobuyuki; Sakamoto, Isao

    1997-03-01

    Since amorphous alloys are generally highly resistant to irradiation and their critical radiation dose is an order of magnitude higher for Fe-B amorphous alloy than Mo-methods, these alloys are expected to become applicable as for fusion reactor materials. The authors investigated {alpha}-Fe crystallization in an amorphous alloy, Fe{sub 80}B{sub 20} using internal conversion electron Moessbauer spectroscopy. The amount of {alpha}-Fe component was found to increase by raising the He-irradiation dose. The target part was modified to enable He ion radiation at a lower temperature (below 400 K) by cooling with Peltier element. Fe{sub 80}B{sub 20} amorphous alloy was cooled to keep the temperature at 300 K and exposed to 40 keV He ion at 1-3 x 10{sup 8} ions/cm{sup 2}. The amount of {alpha}-Fe crystal in each sample was determined. The crystal formation was not observed for He ion radiation below 2 x 10{sup 18} ions/cm{sup 2}, but that at 3 x 10{sup 8} ions/ cm{sup 2} produced a new phase ({delta} +0.40 mm/sec, {Delta} = 0.89 mm/sec). The decrease in the radiation temperature from 430 to 300 K resulted to extremely repress the production of {alpha}-Fe crystal, suggesting that the crystallization induced by He-radiation cascade is highly depending on the radiation temperature. (M.N.)

  19. Photocatalytic and magnetic behaviors of BiFeO{sub 3} thin films deposited on different substrates

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hao-Min; Wang, Huan-Chun; Shen, Yang; Lin, Yuan-Hua, E-mail: linyh@tsinghua.edu.cn; Nan, Ce-Wen [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2014-11-07

    Single phase polycrystalline BiFeO{sub 3} thin films were grown on three different substrates via chemical solution deposition. Our results indicate that the band gap of as-prepared BiFeO{sub 3} films can be tuned (2.02–2.67 eV) by the grain size effects caused by the substrates. These BiFeO{sub 3} films show good photocatalytic properties by the degradation of Congo red solution under visible-light irradiation (λ{sub  }> 400 nm). Additionally, weak ferromagnetic behaviors can be observed at room temperature in all the films, which should be correlated to the destruction of the incommensurate cycloid spin structure of BiFeO{sub 3} phase and the coexistence of Fe{sup 3+} and Fe{sup 2+} as confirmed by X-ray photoelectron spectroscopy.

  20. Growth of ultra-thin FeO(100) films on Ag(100): A combined XPS, LEED and CEMS study

    Science.gov (United States)

    Abreu, G. J. P.; Paniago, R.; Pfannes, H.-D.

    2014-01-01

    The production and characterization of ultra-thin iron oxide films grown on an atomically clean Ag(100) surface by molecular beam epitaxy (MBE) is presented. The goal of this work was to prepare ultra-thin FeO(100) with excellent crystallographic quality. The films were prepared with high purity 57Fe and O2 and afterwards analyzed in situ by means of Low Energy Electron Diffraction (LEED), X-Ray Photoelectron Spectroscopy (XPS) and Conversion Electron Mössbauer Spectroscopy (CEMS). During preparation the evaporation rate, the O2 partial pressure, film thickness and annealing procedures were varied. The analysis of the various samples showed that in general a mixture of FeO and Fe3O4 phases is obtained. We determined the best conditions to produce the desired oxide (FeO). Besides the paramagnetic phase, the antiferromagnetic phase of the FeO films was characterized by low temperature Mössbauer spectra.

  1. Influences of Sputtering Angles and Annealing Temperatures on the Magnetic and Magnetostrictive Performances of TbFe Films

    Institute of Scientific and Technical Information of China (English)

    Hongchuan JIANG; Wanli ZHANG; Wenxu ZHANG; Shiqing YANG; Huaiwu ZHANG

    2005-01-01

    To increase the low-field magnetostriction of TbFe films, the influences of sputtering angles and annealing temperatures on its magnetic and magnetostrictive performances were systematically investigated. With the change in detection of magnetic domains by MFM (magnetic force microscopy) indicates that the easy magnetization direction shifts gradually from perpendicular to parallel to the film plane with decreasing sputtering angles. Annealing can enhance the magnetization and magnetostriction of the TbFe films. However, at too high annealing temperature,both the magnetization and magnetostriction of the TbFe films were suppressed to some extent.

  2. Circular patterns of calcium oxalate crystals induced by defective Langmuir-Blodgett film

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The injury of the renal epithelial cell membrane can promote the nucleation of nascent crystals, as well as adhesion of crystals on it. It thus accelerates the formation of renal calculi. In this paper, the defective Langmuir-Blodgett(LB)films were used as a model system to simulate the injured renal epithelial cell membrane. The microcosmic structure of the defective LB film and the molecular mechanism of the effect of this film on nucleation, growth, deposited patterns and adhesion of calcium oxalate monohydrate(COM)were investigated. The circular defective domains were formed in dipalmitoylphosphatidylcholine(DPPC)LB film after the film was treated by potassium oxalate. These domains could induce ring-shaped patterns of COM crystals. In comparison, the LB film without pretreatment by potassium oxalate only induced random growth of hexagonal COM crystals. As the crystallization time increased, the size of COM crystals in the patterns increased, the crystal patterns changed from empty circles to solid circles, and the number of the circular patterns with small size(5-20μm)increased. The results would shed light on the molecular mechanism of urolithiasis induced by injury of the renal epithelial membrane at the molecular and supramolecular level.

  3. Circular patterns of calcium oxalate crystals induced by defective Langmuir-Blodgett film

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The injury of the renal epithelial cell membrane can promote the nucleation of nascent crystals, as well as adhesion of crystals on it. It thus accelerates the formation of renal calculi. In this paper, the defective Langmuir-Blodgett (LB) films were used as a model system to simulate the injured renal epithelial cell membrane. The microcosmic structure of the defective LB film and the molecular mechanism of the effect of this film on nucleation, growth, deposited patterns and adhesion of calcium oxalate monohydrate (COM) were investigated. The circular defective domains were formed in dipalmitoylphosphatidylcholine (DPPC) LB film after the film was treated by potassium oxalate. These domains could induce ring-shaped patterns of COM crystals. In comparison, the LB film without pretreatment by potassium oxalate only induced random growth of hexagonal COM crystals. As the crystallization time increased, the size of COM crystals in the patterns increased, the crystal patterns changed from empty circles to solid circles, and the number of the circular patterns with small size (5-20 μm) increased. The results would shed light on the molecular mechanism of urolithiasis induced by injury of the renal epithelial membrane at the molecular and supramolecular level.

  4. Synthesis and crystal structure of NaMgFe(MoO43

    Directory of Open Access Journals (Sweden)

    Manel Mhiri

    2016-06-01

    Full Text Available The iron molybdate NaMgFe(MoO43 {sodium magnesium iron(III tris[molybdate(VI]} has been synthesized by the flux method. This compound is isostructural with α-NaFe2(MoO43 and crystallizes in the triclinic space group P-1. Its structure is built up from [Mg,Fe]2O10 units of edge-sharing [Mg,Fe]O6 octahedra which are linked to each other through the common corners of [MoO4] tetrahedra. The resulting anionic three-dimensional framework leads to the formation of channels along the [101] direction in which the Na+ cations are located.

  5. Quantum oscillations in EuFe2As2 single crystals

    Science.gov (United States)

    Rosa, P. F. S.; Zeng, B.; Adriano, C.; Garitezi, T. M.; Grant, T.; Fisk, Z.; Balicas, L.; Johannes, M. D.; Urbano, R. R.; Pagliuso, P. G.

    2014-11-01

    Quantum oscillation measurements provide relevant information about the Fermi surface (FS) properties of strongly correlated metals. Here, we report on the Shubnikov-de Haas effect via high-field resistivity measurements of EuFe2As2 (Eu122) and BaFe2As2 (Ba122) single crystals. Although both pnictide compounds are isovalent with similar effective masses and density of states, at the Fermi level, our results reveal subtle changes in their fermiology. Remarkably, although the spin-density-wave (SDW) ordering temperature is higher in the Eu-rich end, Eu122 displays a much more isotropic and three-dimensional-like FS when compared with Ba122, in agreement with band structure calculations. Our experimental results suggest an anisotropic contribution of the Fe 3 d orbitals to the FS in Ba122. We speculate that this orbital differentiation may be responsible for the suppression of the SDW phase in the FeAs-based compounds.

  6. Studies on high-moment soft magnetic FeCo/Co thin films

    Institute of Scientific and Technical Information of China (English)

    Fu Yu; Yang Zheng; Matsumoto Mitsunori; Liu Xiao-Xi; Morisako Akimitsu

    2006-01-01

    The dependences of soft magnetic properties and microstructures of the sputtered FeCo (=-Fe65Co3s) films on Co underlayer thickness tCo, FeCo thickness tFeCo, substrate temperature Ts and target-substrate spacing dT-S are studied. FeCo single layer generally shows a high coercivity with no obvious magnetic anisotropy. Excellent soft magnetic properties with saturation magnetization μ0Ms of 2.35 T and hard axis coercivity Hch of 0.25 kA/m in FeCo films can be achieved by introducing a Co underlayer. It is shown that sandwiching a Co underlayer causes a change in orientation and reduction in grain size from 70 nm to about 10 nm in the FeCo layer. The magnetic softness can be explained by the Hoffmann's ripple theory due to the effect of grain size. The magnetic anisotropy can be controlled by changing dT-S, and a maximum of 14.3 kA/m for anisotropic field Hk is obtained with dT-S=18.0 cm.

  7. Electrochemical control of the phase transition of ultrathin FeRh films

    Science.gov (United States)

    Jiang, M.; Chen, X. Z.; Zhou, X. J.; Cui, B.; Yan, Y. N.; Wu, H. Q.; Pan, F.; Song, C.

    2016-05-01

    We investigate the electrical manipulation of the phase transition in ultrathin FeRh films through a combination of ionic liquid and oxide gating. The 5 nm-thick FeRh films show an antiferromagnetic-ferromagnetic transition at around 275 K with in-plane magnetic field of 70 kOe. A negative gate voltage seriously suppresses the transition temperature to ˜248 K, while a positive gate voltage does the opposite but with a smaller tuning amplitude. The formation of electric double layer associated with a large electric field induces the migration of oxygen ions between the oxide gate and the FeRh layer, producing the variation of Fe moments in antiferromagnetic FeRh accompanied by the modulation of the transition temperature. Such a modulation only occurs within several nanometers thick scale in the vicinity of FeRh surface. The reversible control of FeRh phase transition by electric field might pave the way for non-volatile memories with low power consumption.

  8. Strain engineering for controlled growth of thin-film FeNi L10

    Science.gov (United States)

    Frisk, Andreas; Hase, Thomas P. A.; Svedlindh, Peter; Johansson, Erik; Andersson, Gabriella

    2017-03-01

    FeNi thin films in the L10 phase were successfully grown by magnetron sputtering on HF-etched Si≤ft(0 0 1\\right) substrates on Cu/Cu100‑x Ni x buffers. The strain of the FeNi layer, {{(c/a)}\\text{FeNi}} , was varied in a controlled manner by changing the Ni content of the Cu100‑x Ni x buffer layer from x=0~\\text{at}. % to x=90~\\text{at}. % , which influenced the common in-plane lattice parameter of the CuNi and FeNi layers. The presence of the L10 phase was confirmed by resonant x-ray diffraction measurements at various positions in reciprocal space. The uniaxial magnetocrystalline anisotropy energy {{K}\\text{U}} is observed to be smaller (around 0.35 MJ m‑3) than predicted for a perfect FeNi L10 sample, but it is larger than for previously studied films. No notable variation in {{K}\\text{U}} with strain state {{(c/a)}\\text{FeNi}} is observed in the range achieved (0.99≲ {{(c/a)}\\text{FeNi}}≲ 1.02 ), which is in agreement with theoretical predictions.

  9. Magnetoelectricity in CoFe2O4 nanocrystal-P(VDF-HFP) thin films.

    Science.gov (United States)

    Liu, Xiaohua; Liu, Shuangyi; Han, Myung-Geun; Zhao, Lukas; Deng, Haiming; Li, Jackie; Zhu, Yimei; Krusin-Elbaum, Lia; O'Brien, Stephen

    2013-09-03

    Transition metal ferrites such as CoFe2O4, possessing a large magnetostriction coefficient and high Curie temperature (Tc > 600 K), are excellent candidates for creating magnetic order at the nanoscale and provide a pathway to the fabrication of uniform particle-matrix films with optimized potential for magnetoelectric coupling. Here, a series of 0-3 type nanocomposite thin films composed of ferrimagnetic cobalt ferrite nanocrystals (8 to 18 nm) and a ferroelectric/piezoelectric polymer poly(vinylidene fluoride-co-hexafluoropropene), P(VDF-HFP), were prepared by multiple spin coating and cast coating over a thickness range of 200 nm to 1.6 μm. We describe the synthesis and structural characterization of the nanocrystals and composite films by XRD, TEM, HRTEM, STEM, and SEM, as well as dielectric and magnetic properties, in order to identify evidence of cooperative interactions between the two phases. The CoFe2O4 polymer nanocomposite thin films exhibit composition-dependent effective permittivity, loss tangent, and specific saturation magnetization (Ms). An enhancement of the effective permittivity and saturation magnetization of the CoFe2O4-P(VDF-HFP) films was observed and directly compared with CoFe2O4-polyvinylpyrrolidone, a non-ferroelectric polymer-based nanocomposite prepared by the same method. The comparison provided evidence for the observation of a magnetoelectric effect in the case of CoFe2O4-P(VDF-HFP), attributed to a magnetostrictive/piezoelectric interaction. An enhancement of Ms up to +20.7% was observed at room temperature in the case of the 10 wt.% CoFe2O4-P(VDF-HFP) sample.

  10. Iron pyrite thin films synthesized from an Fe(acac)3 ink.

    Science.gov (United States)

    Seefeld, Sean; Limpinsel, Moritz; Liu, Yu; Farhi, Nima; Weber, Amanda; Zhang, Yanning; Berry, Nicholas; Kwon, Yon Joo; Perkins, Craig L; Hemminger, John C; Wu, Ruqian; Law, Matt

    2013-03-20

    Iron pyrite (cubic FeS2) is a promising candidate absorber material for earth-abundant thin-film solar cells. Here, we report on phase-pure, large-grain, and uniform polycrystalline pyrite films that are fabricated by solution-phase deposition of an iron(III) acetylacetonate molecular ink followed by sequential annealing in air, H2S, and sulfur gas at temperatures up to 550 °C. Phase and elemental compositions of the films are characterized by conventional and synchrotron X-ray diffraction, Raman spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy (XPS). These solution-deposited films have more oxygen and alkalis, less carbon and hydrogen, and smaller optical band gaps (E(g) = 0.87 ± 0.05 eV) than similar films made by chemical vapor deposition. XPS is used to assess the chemical composition of the film surface before and after exposure to air and immersion in water to remove surface contaminants. Optical measurements of films rich in marcasite (orthorhombic FeS2) show that marcasite has a band gap at least as large as pyrite and that the two polymorphs share similar absorptivity spectra, in excellent agreement with density functional theory models. Regardless of the marcasite and elemental impurity contents, all films show p-type, weakly activated transport with curved Arrhenius plots, a room-temperature resistivity of ~1 Ω cm, and a hole mobility that is too small to measure by Hall effect. This universal electrical behavior strongly suggests that a common defect or a hole-rich surface layer governs the electrical properties of most FeS2 thin films.

  11. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films.

    Science.gov (United States)

    Zhang, Huairuo; Reaney, Ian M; Marincel, Daniel M; Trolier-McKinstry, Susan; Ramasse, Quentin M; MacLaren, Ian; Findlay, Scott D; Fraleigh, Robert D; Ross, Ian M; Hu, Shunbo; Ren, Wei; Rainforth, W Mark

    2015-08-14

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)(3+) Fe(3+)O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community.

  12. Structural and magnetic properties of Cu-alloyed FePd films

    Energy Technology Data Exchange (ETDEWEB)

    Polit, A., E-mail: aleksander.polit@gmail.com [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland); Makarov, D., E-mail: d.makarov@ifw-dresden.de [Chemnitz University of Technology, Institute of Physics, D-09107 Chemnitz (Germany); Brombacher, C., E-mail: Christoph.Brombacher@vacuumschmelze.com [Chemnitz University of Technology, Institute of Physics, D-09107 Chemnitz (Germany); Krupinski, M., E-mail: michal.krupinski@ifj.edu.pl [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland); Perzanowski, M., E-mail: marcin.perzanowski@ifj.edu.pl [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland); Zabila, Y., E-mail: yevhen.zabila@ifj.edu.pl [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland); Albrecht, M., E-mail: manfred.albrecht@physik.uni-augsburg.de [Chemnitz University of Technology, Institute of Physics, D-09107 Chemnitz (Germany); Marszałek, M., E-mail: marta.marszalek@ifj.edu.pl [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland)

    2015-05-01

    Multilayer films [Cu(d Å)/Fe(9 Å)/Pd(11 Å)]{sub 5} were deposited at room temperature on Si(001)/SiO{sub 2}(400 nm) substrates. In order to induce chemical L1{sub 0} ordering, the as-deposited samples were post-annealed by rapid thermal annealing (RTA) at 600 °C for 90 s followed additionally by heating in ultra-high vacuum (UHV) at 700 °C up to several hours. In this study the impact of post-annealing on the structural and magnetic properties of FePdCu alloy films in dependence on the Cu content was investigated. It was found that the addition of Cu to the FePd alloy has a strong influence on the chemical ordering process and the (001) texture formation. After the RTA treatment only an isotropic distribution of the easy axis of magnetization with coercive fields in the range of a few hundred mT was observed. In contrast, samples which were additionally heated for 1 h at 700 °C revealed an out-of-plane easy axis of magnetization with an effective magnetic anisotropy of about 2×10{sup 5} J/m{sup 3} for the sample containing 10 at% of Cu. - Highlights: • Fabrication by two-step annealing of FePdCu thin alloy films. • The impact of post-annealing on the structural and magnetic properties of FePdCu alloy films. • The addition of Cu to the FePd alloy has a strong influence on the chemical ordering process and the (001) texture formation. • Importance of texture in polycrystalline L1{sub 0} FePdCu alloy for perpendicular magnetic anisotropy.

  13. Crystal structure and electronic properties of the new compounds, U 6Fe 16Si 7 and its interstitial carbide U 6Fe 16Si 7C

    Science.gov (United States)

    Berthebaud, D.; Tougait, O.; Potel, M.; Lopes, E. B.; Gonçalves, A. P.; Noël, H.

    2007-10-01

    The new compounds U6Fe16Si7 and U6Fe16Si7C were prepared by arc-melting and subsequent annealing at 1500 °C. Single-crystal X-ray diffraction showed that they crystallize in the cubic space group Fm3¯m (No. 225), with unit-cell parameters at room temperature a=11.7206(5) Å for U6Fe16Si7 and a=11.7814(2) Å for U6Fe16Si7C. Their crystal structures correspond to ordered variants of the Th6Mn23 type. U6Fe16Si7 adopts the Mg6Cu16Si7 structure type, whereas U6Fe16Si7C crystallizes with a novel "filled" quaternary variant. The inserted carbon is located in octahedral cages formed by six U atoms, with U-U interatomic distances of 3.509(1) Å. Insertion of carbon in the structure of U6Fe16Si7 has a direct influence on the U-Fe and Fe-Fe interatomic distances. The electronic properties of both compounds were investigated by means of DC susceptibility, electrical resistivity and thermopower. U6Fe16Si7 is a Pauli paramagnet. Its electrical resistivity and thermopower point out that it cannot be classified as a simple metal. The magnetic susceptibility of U 6Fe 16Si 7C is best described over the temperature range 100-300 K by using a modified Curie-Weiss law with an effective magnetic moment of 2.3(2) μB/U, a paramagnetic Weiss temperature, θp=57(2) K and a temperature-independent term χ0=0.057(1) emu/mol. Both the electrical resistivity and thermopower reveal metallic behavior.

  14. Optical Properties and Electrochemical Performance of LiFePO4 Thin Films Deposited on Transparent Current Collectors.

    Science.gov (United States)

    Lee, HyunSeok; Yim, Haena; Kim, Kwang-Bum; Choi, Ji-Won

    2015-11-01

    LiFePO4 thin film cathodes are deposited on various transparent conducting oxide thin films on glass, which are used as cathode current collectors. The XRD patterns show that the thin films have the phase of LiFePO4 with an ordered olivine structure indexed to the orthorhombic Pmna space group. LiFePO4 thin film deposited on various TCO glass substrates exhibits transmittance of about 53%. The initial specific discharge capacities of LiFePO4 thin films are 25.0 μAh/cm2 x μm on FTO, 33.0 μAh/cm2 x μm on ITO, and 13.0 μAh/cm2 x μm on AZO coated glass substrates. Interestingly, the retention capacities of LiFePO4 thin films are 76.0% on FTO, 31.2% on ITO, and 37.7% on AZO coated glass substrates at 20th cycle. The initial specific discharge capacity of the LiFePO4/FTO electrode is slightly lower, but the discharge capacities of the LiFePO4/FTO electrode relatively decrease less than those of the others such as LiFePO4/ITO and LiFePO4/AZO with cycling. The results reported here provide the high transparency of LiFePO4 thin films cathode materials and the good candidate as FTO current collector of the LiFePO4 thin film cathode of transparent thin film rechargeable batteries due to its high transparency and cyclic retention.

  15. In situ RHEED and XPS studies of epitaxial thin alpha-Fe2O3 films on sapphire

    NARCIS (Netherlands)

    Fujii, T; Alders, D; Voogt, FC; Hibma, T; Thole, BT; Sawatzky, GA

    1996-01-01

    In situ RHEED and XPS measurements of epitaxial alpha-Fe2O3(0001) films are reported as a function of the number of deposited monolayers. The films were prepared on alpha-Al2O3(0001) substrates by MBE. The RHEED patterns suggest that layer-by-layer growth of alpha-Fe2O3(0001) occurs for the first fe

  16. Kinetic Behavior of LiFePO4/C Thin Film Cathode Material for Lithium-Ion Batteries

    OpenAIRE

    Kucinskis, G; Bajārs, G; Kleperis, J.; Smits, J.

    2010-01-01

    LiFePO4 was prepared in a solid state synthesis with various levels of carbon content. LiFePO4/C thin films were obtained via magnetron sputtering. The surface morphology and structure was examined. Electrochemical properties of LiFePO4/C were studied, by using cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. Thin films acquired show a potential use as a cathode in lithium ion batteries, displaying charge capacity up to 34 mAh g-1.

  17. High field transport properties of MBE processed Fe-based superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Kazumasa [Nagoya University (Japan); IFW Dresden (Germany)

    2015-07-01

    It has been reported that Fe-based superconductors show high upper critical fields with low anisotropies at low temperatures. Hence these materials may offer a unique possibility for high field magnet applications. However, only a few reports on high-field transport properties of Co-doped Ba-122 and Fe(Se,Te) have been published and the only one for SmFeAs(O,F) thin films to date. In order to use this material class for applications, the knowledge of in-field and its orientation dependence of transport properties in a wide range of external fields need to be clarified. In this talk, I will report on high-field (up to dc 45 T) transport properties of P-doped Ba-122, SmFeAs(O,F) and NdFeAs(O,F) thin films prepared by MBE. Although P-doped Ba-122 has the lowest T{sub c}, self-field J{sub c} of over 6 MA/cm{sup 2} at 4.2 K is recorded, which is the highest value ever reported in Fe-based superconductors. Additionally, in-field performance of P-doped Ba-122 shows comparable to those of NdFeAs(O,F) and SmFeAs(O,F) for Hc. On the other hand, both NdFeAs(O,F) and SmFeAs(O,F) exhibited higher J{sub c} for H parallel ab due to the intrinsic pinning. These results indicate that P-doped Ba-122 is the most promising candidates for high-field magnet applications.

  18. Electric detection of the spin-Seebeck effect in Ni and Fe thin films at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ota, T; Uchida, K; Kitamura, Y; Yoshino, T; Nakayama, H; Saitoh, E, E-mail: ota@z5.keio.j [Institute for Materials Research, Tohoku University, Sendai, 980-8577 (Japan)

    2010-01-01

    The spin-Seebeck effects in Ni and Fe thin films have been investigated by using the inverse spin-Hall effect in a Pt film. The experimental results show that the sign of the spin-Seebeck coefficient for Ni is opposite to those for Fe and Ni{sub 81}Fe{sub 19} and that the magnitude of the spin-Seebeck coefficients for Ni and Ni{sub 81}Fe{sub 19} are much greater than that for Fe at room temperature. This material dependence of the spin-Seebeck coefficient is different from that of the conventional Seebeck coefficient.

  19. Structural Characteristics and Crystallization of Metallic Glass Sputtered Films by Using Zr System Target

    Directory of Open Access Journals (Sweden)

    Katsuyoshi Kondoh

    2008-01-01

    Full Text Available Zr-Al-Ni-Cu thin films were deposited by the radio-frequency sputtering method at low substrate temperature using three kinds of targets: Zr55Al10Ni5Cu30 bulk metallic glass target (α-BMG target, crystallized bulk metallic glass target (c-BMG target, and an elemental composite target composed of each Zr, Al, Ni chips, and Cu plate. XRD profiles of the films prepared when using these targets indicated that all of the films showed amorphous structures. While XRD profiles of the films using α- and c-BMG targets revealed a broad peak of 2θ=38 degree in the same way as the α-BMG target indicating amorphous structures, that of the film using elemental composite targets showed a broad peak of 2θ=42 degree, which is higher compared to the latter material. As a result of annealing the films at various temperatures for 900 seconds, the film using the α-BMG target showed a crystallization temperature of 748 K, higher than that of BMG with 723 K, while the other films had lower crystallization temperatures below 723 K. XRD profiles also indicated that the crystallized compounds of the films were different from those of BMG target.

  20. Tunneling Magneto-resistance in grain boundary tailored Fe3O4 nano structured thin films

    Science.gov (United States)

    Kumar, Ankit; Behera, Nilamani; Husain, Sajid; Chaudhary, Sujeet; Pandya, Dinesh K.

    2017-05-01

    The pulse DC sputtered nanostructured Fe3O4 thin films have been subjected to hydrocarbon treatment and vacuum annealing to investigate their effect on grain boundaries. Remarkably, this treatment causes a change in the crystallographic structure of the film from polycrystalline to (440) oriented one and enhancement in film conductivity. Hopping conduction mechanism changes to nearest-neighbor hoping above Verwey transition temperature of 110 K on treatment. Treatment also leads to grain boundary modification by incorporation of antiferro defects that inhibit an increase in MR despite enhanced electron conduction across grain boundaries. Our results follow the non-homogeneous grain boundary model.

  1. Photoelectrocatalytic activity of liquid phase deposited α-Fe{sub 2}O{sub 3} films under visible light illumination

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Man; Pu, Wenhong; Pan, Shichang [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China); Okoth, Otieno Kevin [School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China); Yang, Changzhu [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China); Zhang, Jingdong, E-mail: zhangjd@mail.hust.edu.cn [School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China)

    2015-11-05

    Liquid phase deposition (LPD) technique was employed to prepare α-Fe{sub 2}O{sub 3} films for photoelectrocatalytic degradation of pollutants. The obtained LPD films were characterized by various surface analysis techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). The results indicated that α-Fe{sub 2}O{sub 3} films with porous structure were successfully deposited on the titanium substrates by the LPD process. The UV–Visible diffuse reflectance spectroscopic (DRS) analysis showed that the obtained LPD α-Fe{sub 2}O{sub 3} film mainly absorbed visible light, which was advantageous to the utilization of solar energy. Under visible light illumination, the Fe{sub 2}O{sub 3} film electrodes exhibited sensitive photocurrent responses, which were affected by the calcination temperature. Consistent with the photocurrent analysis, the α-Fe{sub 2}O{sub 3} film calcined at 600 °C showed the best photoelectrocatalytic performance, and different organic pollutants such as methyl orange (MO) and p-nitrophenol (PNP) were effectively degraded over the LPD film electrode by photoelectrocatalytic treatment under visible light illumination. - Highlights: • α-Fe{sub 2}O{sub 3} film is prepared by liquid phase deposition process. • LPD α-Fe{sub 2}O{sub 3} film has a porous structure and absorbs visible light. • Calcination temperature shows a significant effect on the PEC performance of α-Fe{sub 2}O{sub 3} film. • α-Fe{sub 2}O{sub 3} film is efficient for photoelectrocatalytic degradation of pollutants.

  2. Mössbauer study of oxide films of Fe-, Sn-, Cr- doped zirconium alloys during corrosion in autoclave

    Science.gov (United States)

    Filippov, V. P.; Bateev, A. B.; Lauer, Yu. A.

    2016-12-01

    Mössbauer investigations were used to compare iron atom states in oxide films of binary Zr-Fe, ternary Zr-Fe-Cu and quaternary Zr-Fe-Cr-Sn alloys. Oxide films are received in an autoclave at a temperature of 350-360 °C and at pressure of 16.8 MPa. The corrosion process decomposes the intermetallic precipitates in alloys and forms metallic iron with inclusions of chromium atoms α-Fe(Cr), α-Fe(Cu), α-Fe 2O3 and Fe 3O4 compounds. Some iron ions are formed in divalent and in trivalent paramagnetic states. The additional doping influences on corrosion kinetics and concentration of iron compounds and phases formed in oxide films. It was shown the correlation between concentration of iron in different chemical states and corrosion resistance of alloys.

  3. Mössbauer study of oxide films of Fe-, Sn-, Cr- doped zirconium alloys during corrosion in autoclave

    Energy Technology Data Exchange (ETDEWEB)

    Filippov, V. P., E-mail: vpfilippov@mephi.ru; Bateev, A. B.; Lauer, Yu. A. [National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute) (Russian Federation)

    2016-12-15

    Mössbauer investigations were used to compare iron atom states in oxide films of binary Zr-Fe, ternary Zr-Fe-Cu and quaternary Zr-Fe-Cr-Sn alloys. Oxide films are received in an autoclave at a temperature of 350–360 °C and at pressure of 16.8 MPa. The corrosion process decomposes the intermetallic precipitates in alloys and forms metallic iron with inclusions of chromium atoms α–Fe(Cr), α–Fe(Cu), α–Fe {sub 2}O{sub 3} and Fe {sub 3}O{sub 4} compounds. Some iron ions are formed in divalent and in trivalent paramagnetic states. The additional doping influences on corrosion kinetics and concentration of iron compounds and phases formed in oxide films. It was shown the correlation between concentration of iron in different chemical states and corrosion resistance of alloys.

  4. Crystal growth, electronic structure, and properties of Ni-substituted FeGa3

    Science.gov (United States)

    Likhanov, Maxim S.; Verchenko, Valeriy Yu.; Bykov, Mikhail A.; Tsirlin, Alexander A.; Gippius, Andrei A.; Berthebaud, David; Maignan, Antoine; Shevelkov, Andrei V.

    2016-04-01

    Crystals of the Fe1-xNixGa3 limited solid solution (x<0.045) have been grown from gallium flux. We have explored the electronic structure as well as magnetic and thermoelectric properties of Fe0.975Ni0.025Ga3 in comparison with Fe0.95Co0.05Ga3, following the rigid band approach and assuming that one Ni atom donates twice the number of electrons as one Co atom. However, important differences between the Co- and Ni-doped compounds are found below 620 K, which is the temperature of the metal-to-insulator transition for both compounds. We have found that Fe0.975Ni0.025Ga3 displays lower degree of spatial inhomogeneity on the local level and exhibits diamagnetic behavior with a broad shallow minimum in the magnetic susceptibility near 35 K, in sharp contrast with the Curie-Weiss paramagnetism of Fe0.95Co0.05Ga3. Transport measurements have shown the maximum of the thermoelectric figure-of-merit ZT of 0.09 and 0.14 at 620 K for Fe0.975Ni0.025Ga3 and Fe0.95Co0.05Ga3, respectively.

  5. Solution Coating of Superior Large-Area Flexible Perovskite Thin Films with Controlled Crystal Packing

    KAUST Repository

    Li, Jianbo

    2017-05-08

    Solution coating of organohalide lead perovskites offers great potential for achieving low-cost manufacturing of large-area flexible optoelectronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of crystal packing. Herein, this study reports using solution shearing to confine crystal nucleation and growth in large-area printed MAPbI3 thin films. Near single-crystalline perovskite microarrays are demonstrated with a high degree of controlled macroscopic alignment and crystal orientation, which exhibit significant improvements in optical and optoelectronic properties comparing with their random counterparts, spherulitic, and nanograined films. In particular, photodetectors based on the confined films showing intense anisotropy in charge transport are fabricated, and the device exhibits significantly improved performance in all aspects by one more orders of magnitude relative to their random counterparts. It is anticipated that perovskite films with controlled crystal packing may find applications in high-performance, large-area printed optoelectronics, and solar cells.

  6. Ultralong Lifespan and Ultrafast Li Storage: Single-Crystal LiFePO4 Nanomeshes.

    Science.gov (United States)

    Zhang, Yan; Zhang, Hui Juan; Feng, Yang Yang; Fang, Ling; Wang, Yu

    2016-01-27

    A novel LiFePO4 material, in the shape of a nanomesh, has been rationally designed and synthesized based on the low crystal-mismatch strategy. The LiFePO4 nanomesh possesses several advantages in morphology and crystal structure, including a mesoporous structure, its crystal orientation that is along the [010] direction, and a shortened Li-ion diffusion path. These properties are favorable for their application as cathode in Li-ion batteries, as these will accelerate the Li-ion diffusion rate, improve the Li-ion exchange between the LiFePO4 nanomesh and the electrolyte, and reduce the Li-ion capacitive behavior during Li intercalation. So the LiFePO4 nanomesh exhibits a high specific capacity, enhanced rate capability, and strengthened cyclability. The method developed here can also be extended to other similar systems, for instance, LiMnPO4 , LiCoPO4 , and LiNiPO4 , and may find more applications in the designed synthesis of functional materials.

  7. Crystallization in Fe- and Co-Based Amorphous Alloys Studied by In-Situ X-Ray Diffraction

    Science.gov (United States)

    Zhang, L. J.; Yu, P. F.; Cheng, H.; Zhang, M. D.; Liu, D. J.; Zhou, Z.; Jin, Q.; Liaw, P. K.; Li, G.; Liu, R. P.

    2016-12-01

    The amorphous alloys, Fe80Si20, Fe78Si9B13, and Fe4Co67Mo1.5Si16.5B11, were prepared by the spinning method in pure argon. The crystallization behaviors of the three amorphous alloys were researched by in-situ X-ray diffraction (XRD), and the crystallization activation energy was calculated, based on the results of differential scanning calorimetry. The crystallization mechanism of the Fe- and Co-based alloys was analyzed, based on the experimental data. The transformation kinetics was described in terms of Johnson-Mehl-Avrami kinetics, except that the Avrami exponent of the Fe78Si9B13 amorphous alloy annealed at 753 K (480 °C) was 4.12; the obtained values for the overall Avrami exponents of the other three amorphous alloys were below 1, as usually found for the Fe-Si amorphous alloys.

  8. Gilbert damping constant of FePd alloy thin films estimated by broadband ferromagnetic resonance

    Directory of Open Access Journals (Sweden)

    Kawai T.

    2014-07-01

    Full Text Available Magnetic relaxation of FePd alloy epitaxial thin films with very flat surfaces prepared on MgO(001 substrate are measured by in-plane broadband ferromagnetic resonance (FMR. Magnetic relaxation is investigated as Δω for FMR absorption peak by frequency sweep measurements. ΔH is calculated by using the measured Δω. Gilbert damping constant, α, is estimated by employing a straight line fitting of the resonant frequency dependence of ΔH. The α value for an FePd film deposited at 200 ˚C, which shows disordered A1 structure, is 0.010 and ΔH0, which is frequency independent part of ΔH, is 10 Oe. The α value for a film annealed at 400 ˚C, which shows partially L10 ordered structure (S=0.32, is 0.013, which is slightly larger than that for the disorder A1 structure film. However, ΔH0 for the annealed film is 85 Oe, which is much larger than that for the film with disordered structure. The results show that the magnetic relaxation of the 400 ˚C annealed film is mainly dominated by ΔH0, which is related with magnetic in-homogeneity caused by the appearance of perpendicular anisotropy of partially ordered phase.

  9. Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation.

    Science.gov (United States)

    Wang, Jie-Su; Jin, Kui-Juan; Guo, Hai-Zhong; Gu, Jun-Xing; Wan, Qian; He, Xu; Li, Xiao-Long; Xu, Xiu-Lai; Yang, Guo-Zhen

    2016-12-01

    BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films.

  10. Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

    Science.gov (United States)

    Wang, Jie-su; Jin, Kui-juan; Guo, Hai-zhong; Gu, Jun-xing; Wan, Qian; He, Xu; Li, Xiao-long; Xu, Xiu-lai; Yang, Guo-zhen

    2016-01-01

    BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films. PMID:27905565

  11. Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

    Science.gov (United States)

    Wang, Jie-Su; Jin, Kui-Juan; Guo, Hai-Zhong; Gu, Jun-Xing; Wan, Qian; He, Xu; Li, Xiao-Long; Xu, Xiu-Lai; Yang, Guo-Zhen

    2016-12-01

    BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films.

  12. The structural and magnetic properties of MnBi and exchange coupled MnBi/Fe films

    Energy Technology Data Exchange (ETDEWEB)

    Li, B. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Liu, W., E-mail: wliu@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhao, X.G.; Gong, W.J.; Zhao, X.T.; Wang, H.L. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Kim, D.; Choi, C.J. [Functional Materials Division, Korea Institute of Materials Science, 531 Changwon-daero, Changwon 631-831 (Korea, Republic of); Zhang, Z.D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2014-12-15

    The structural and magnetic properties of MnBi and MnBi/Fe films prepared by magnetron sputtering and in situ vacuum annealing are investigated. MnBi film is highly c-axis textured with perpendicular anisotropy. The out-of-plane coercivity increases with temperature, which reaches to 15 kOe and 21 kOe at 300 K and 400 K, respectively. For exchange coupled MnBi/Fe films, when the thickness of Fe layer is thin, the hysteresis loops show single-phase-like reversal behavior due to the effective interfacial exchange coupling. In comparison with MnBi film, the remanent magnetization enhances. The maximum energy product also improves from 7.6 MGOe to 8.0 MGOe at 300 K, and from 5.7 MGOe to 6.1 MGOe at 400 K. As the thickness of Fe layer exceeds the critical dimension, the two-step reversal behavior is observed, indicating the decoupling of soft Fe layer and neighboring hard MnBi layer. - Highlights: • MnBi film shows perpendicular anisotropy with highly c-axis textured. • At 400 K, MnBi film shows a higher (BH){sub max} than MnBi magnet due to perpendicular anisotropy. • (BH){sub max} of MnBi/Fe film is enhanced due to exchange coupling. • A step emerges on the demagnetization curve of MnBi/Fe film as temperature goes up.

  13. Crystal growth and characterization of CeFe{sub 1-x}Ru{sub x} PO

    Energy Technology Data Exchange (ETDEWEB)

    Balle, Tanita; Kliemt, Kristin; Krellner, Cornelius [Goethe Universitaet Frankfurt, Kristall- und Materiallabor (Germany)

    2016-07-01

    CeRuPO is a one of the few heavy fermion systems, which order ferromagnetically at low temperatures (T{sub C} = 15 K), because of dominant RKKY-interaction. CeFePO on the other hand shows no long-range magnetic order even at low temperatures because of dominant Kondo effect (T{sub K} = 10 K). By substituting CeFePO with ruthenium we can reach a quantum critical point, at which the RKKY-interaction and the Kondo effect are equally strong. To study the quantum critical point, and to enlighten the question if the order stays ferromagnetically down to lowest temperatures, high quality crystals are needed. Here, the growth and characterization of the single crystals will be discussed. We obtained mm-sized single crystals of the unsubstituted CeRuPO and CeFePO by a modified Bridgeman method using tin as a flux. The quality of the crystals was verified by Powder-X-Ray-Diffraction, energy dispersive X-ray spectroscopy and Laue backscattering.

  14. Shape memory effects in [001] Ni55Fe18Ga27 single crystal

    Science.gov (United States)

    Belyaev, S.; Resnina, N.; Nikolaev, V.; Timashov, R.; Gazizullina, A.; Sibirev, A.; Averkin, A.; Krymov, V.

    2017-09-01

    Shape memory effects in Ni55Fe18Ga27 single crystal grown along the [001] direction by the Czochralski method was studied. It was found that deformation of [001] single crystal in the martensite state was realised via reorientation of 10 M martensite and stress-induced transformations: 10 M → 14 M → L10. On unloading, the reverse L10 → 14 M → 10 M transformations occurred and a large unelastic strain recovered. On heating, the oriented 10 M martensite transformed to the L21 austenite phase and the shape memory effect was observed. An increase in preliminary strain resulted in an increase in the shape memory effect value to 4.6%. The [001] Ni55Fe18Ga27 alloy single crystal demonstrated transformation plasticity and shape memory effects on cooling and heating under stress however, an increase in stress decreased the values of these effects. This was caused by stress-induced martensite appearing in the sample during loading in the austenite state, which decreased the volume of the austenite phase that could undergo the martensitic transformation on cooling. The [001] Ni55Fe18Ga27 alloy single crystal demonstrated a two-way shape memory effect and its value depended on the residual strain in a non-monotonic way and the maximum recoverable strain was 0.7%.

  15. 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.

  16. FCC/BCC competition and enhancement of saturation magnetization in nanocrystalline Co-Ni-Fe films

    NARCIS (Netherlands)

    Chechenin, N. G.; Khomenko, E. V.; de Hosson, J. Th. M.

    2007-01-01

    The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films were investigated using a number of techniques. A high saturation magnetic induction up to B-s = 21 kG was attained. An enhancement of the saturation magnetization compared to t

  17. On the GHz frequency response in nanocrystalline FeXN ultra-soft magnetic films

    NARCIS (Netherlands)

    Chechenin, NG; Craus, CB; Chezan, AR; Vystavel, T; Boerma, DO; De Hosson, JTM; Niesen, L; Tidrow, SC; Horwitz, JS; Xi, XX; Levy, J

    2002-01-01

    The periodicity and angular spread of the in-plane magnetization for ultrasoft nanocrystalline FeZrN films were estimated from an analysis of the ripple structure, observed in Lorentz transmission electron microscopy (LTEM) images. The influence of the micromagnetic ripple on the ferromagnetic reson

  18. Growth and Surface Modification of LaFeO3 Thin Films Induced By Reductive Annealing

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, Brendan T.; Zhang, Hongliang; Shutthanandan, V.; Varga, Tamas; Colby, Robert J.; Oleksak, Richard P.; Manandhar, Sandeep; Engelhard, Mark H.; Chambers, Scott A.; Henderson, Michael A.; Herman, Gregory S.; Thevuthasan, Suntharampillai

    2015-03-01

    The electronic and ionic conductivity of perovskite oxides has enabled their use in diverse applications such as automotive exhaust catalysts, solid oxide fuel cell cathodes, and visible light photocatalysts. The redox chemistry at the surface of perovskite oxides is largely dependent on the oxidation state of the metal cations as well as the oxide surface stoichiometry. In this study, LaFeO3 (LFO) thin films grown on yttria-stabilized zirconia (YSZ) was characterized using both bulk and surface sensitive techniques. A combination of in situ reflection high energy electron diffraction (RHEED), x-ray diffraction (XRD), transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS) demonstrated that the film is highly oriented and stoichiometric. The film was annealed in an ultra-high vacuum chamber to simulate reducing conditions and studied by angle-resolved x-ray photoelectron spectroscopy (XPS). Iron was found to exist as Fe(0),