WorldWideScience

Sample records for multilayer interface anisotropy

  1. NMR studies of interfaces, strain and anisotropy in Co/Cu multilayers

    International Nuclear Information System (INIS)

    Thomson, T.; Riedi, P.C.

    1999-01-01

    59 Co NMR studies of multilayers are able to give three direct pieces of information: (i) the crystal phase of Co, fcc (217.4 MHz), hcp (220-228 MHz) and in exotic cases bcc (198 MHz) for films measured at T= 4.2 K, (ii) the nature of the interfaces from low frequency satellite lines, and (iii) the strain state deduced from small changes in the line positions. Extensive studies of Co/Cu multilayer interfacial structures as a function of deposition technique, layer thickness, substrate/buffer layer structure and annealing temperature have been undertaken. This work has shed new light on the relationship between interfacial structure and magnetoresistance and in particular has demonstrated that flat, atomic scale, interfaces lead to greater magnetoresistance. The difference between the Co and Cu lattice constant results in an extensive, tensile in-plane strain developing in Co layers provided that some epitaxial registry is present. Information on strain effects can be obtained from the position and width of the NMR lines. The magnetic anisotropy field can be determined by measuring the field dependence of the enhancement effect due to electronic magnetisation. This provides unique insight into the distribution of magnetic anisotropy within the Co layers, as the enhancement can be investigated independently for each NMR line and, hence, provides environment specific information on magnetic anisotropy at the interfaces and in the interior of the layers

  2. M-Split: A Graphical User Interface to Analyze Multilayered Anisotropy from Shear Wave Splitting

    Science.gov (United States)

    Abgarmi, Bizhan; Ozacar, A. Arda

    2017-04-01

    Shear wave splitting analysis are commonly used to infer deep anisotropic structure. For simple cases, obtained delay times and fast-axis orientations are averaged from reliable results to define anisotropy beneath recording seismic stations. However, splitting parameters show systematic variations with back azimuth in the presence of complex anisotropy and cannot be represented by average time delay and fast axis orientation. Previous researchers had identified anisotropic complexities at different tectonic settings and applied various approaches to model them. Most commonly, such complexities are modeled by using multiple anisotropic layers with priori constraints from geologic data. In this study, a graphical user interface called M-Split is developed to easily process and model multilayered anisotropy with capabilities to properly address the inherited non-uniqueness. M-Split program runs user defined grid searches through the model parameter space for two-layer anisotropy using formulation of Silver and Savage (1994) and creates sensitivity contour plots to locate local maximas and analyze all possible models with parameter tradeoffs. In order to minimize model ambiguity and identify the robust model parameters, various misfit calculation procedures are also developed and embedded to M-Split which can be used depending on the quality of the observations and their back-azimuthal coverage. Case studies carried out to evaluate the reliability of the program using real noisy data and for this purpose stations from two different networks are utilized. First seismic network is the Kandilli Observatory and Earthquake research institute (KOERI) which includes long term running permanent stations and second network comprises seismic stations deployed temporary as part of the "Continental Dynamics-Central Anatolian Tectonics (CD-CAT)" project funded by NSF. It is also worth to note that M-Split is designed as open source program which can be modified by users for

  3. Magnetic anisotropy of Ni/Cr multilayers

    International Nuclear Information System (INIS)

    Kang, S.; Xia, H.

    1997-01-01

    The magnetic anisotropy of Ni/Cr multilayers has been investigated by using vibrating sample magnetometer (VSM) and ferromagnetic resonance techniques (FMR). The FMR spectra are obtained as a function of the orientation of the applied magnetic field from in-plane to out-of-plane. The results are fitted theoretically to determine the magnetic anisotropy. From VSM and FMR, a positive value for Ni/Cr interface anisotropy is obtained, which favours a perpendicular easy axis. The possible mechanism for the perpendicular anisotropy has been discussed and it may be attributed to the magnetostriction, caused by intrinsic stress due to lattice mismatch. (orig.). With 005 figs., 001 tabs

  4. Origin of perpendicular magnetic anisotropy in Co/Ni multilayers

    Science.gov (United States)

    Arora, M.; Hübner, R.; Suess, D.; Heinrich, B.; Girt, E.

    2017-07-01

    We studied the variation in perpendicular magnetic anisotropy of (111) textured Au /N ×[Co /Ni ]/Au films as a function of the number of bilayer repeats N . The ferromagnetic resonance and superconducting quantum interference device magnetometer measurements show that the perpendicular magnetic anisotropy of Co/Ni multilayers first increases with N for N ≤10 and then moderately decreases for N >10 . The model we propose reveals that the decrease of the anisotropy for N reduction in the magnetoelastic and magnetocrystalline anisotropies. A moderate decrease in the perpendicular magnetic anisotropy for N >10 is due to the reduction in the magnetocrystalline and the surface anisotropies. To calculate the contribution of magnetoelastic anisotropy in the Co/Ni multilayers, in-plane and out-of-plane x-ray diffraction measurements are performed to determine the spacing between Co/Ni (111) and (220) planes. The magnetocrystalline bulk anisotropy is estimated from the difference in the perpendicular and parallel g factors of Co/Ni multilayers that are measured using the in-plane and out-of-plane ferromagnetic resonance measurements. Transmission electron microscopy has been used to estimate the multilayer film roughness. These values are used to calculate the roughness-induced surface and magnetocrystalline anisotropy coefficients as a function of N .

  5. Layering and temperature-dependent magnetization and anisotropy of naturally produced Ni/NiO multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, S. D.; Trachylis, D.; Velgakis, M. J. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Kapaklis, V.; Joensson, P. E.; Papaioannou, E. Th. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Delimitis, A. [Chemical Process Engineering Research Institute (CPERI), Centre for Research and Technology Hellas (CERTH), 57001 Thermi, Thessaloniki (Greece); Poulopoulos, P. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Materials Science Department, University of Patras, 26504 Patras (Greece); Fumagalli, P. [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Politis, C. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2012-09-01

    Ni/NiO multilayers were grown by magnetron sputtering at room temperature, with the aid of the natural oxidation procedure. That is, at the end of the deposition of each single Ni layer, air is let to flow into the vacuum chamber through a leak valve. Then, a very thin NiO layer ({approx}1.2 nm) is formed. Simulated x-ray reflectivity patterns reveal that layering is excellent for individual Ni-layer thickness larger than 2.5 nm, which is attributed to the intercalation of amorphous NiO between the polycrystalline Ni layers. The magnetization of the films, measured at temperatures 5-300 K, has almost bulk-like value, whereas the films exhibit a trend to perpendicular magnetic anisotropy (PMA) with an unusual significant positive interface anisotropy contribution, which presents a weak temperature dependence. The power-law behavior of the multilayers indicates a non-negligible contribution of higher order anisotropies in the uniaxial anisotropy. Bloch-law fittings for the temperature dependence of the magnetization in the spin-wave regime show that the magnetization in the multilayers decreases faster as a function of temperature than the one of bulk Ni. Finally, when the individual Ni-layer thickness decreases below 2 nm, the multilayer stacking vanishes, resulting in a dramatic decrease of the interface magnetic anisotropy and consequently in a decrease of the perpendicular magnetic anisotropy.

  6. Enhancement of perpendicular magnetic anisotropy and anomalous hall effect in Co/Ni multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yiwei; Zhang, Jingyan, E-mail: jyzhang@ustb.edu.cn; Jiang, Shaolong; Liu, Qianqian; Li, Xujing; Yu, Guanghua, E-mail: ghyu@mater.ustb.edu.cn

    2016-12-15

    The perpendicular magnetic anisotropy (PMA) and the anomalous Hall effect (AHE) in Co/Ni multilayer were optimized by manipulating its interface structure (inducing HfO{sub 2} capping layer and Pt insertion) and post-annealing treatment. A strong PMA can be obtained in Co/Ni multilayers with HfO{sub 2} capping layer even after annealing at 400 °C. The heavy metal Hf may improve the interfacial spin-orbit coupling, which responsible for the enhanced PMA and high annealing stability. Moreover, the multilayer containing HfO{sub 2} capping layer also exhibited high saturation anomalous Hall resistivity through post-annealing, which is 0.85 μΩ cm after annealing at 375 °C, 211% larger than in the sample at deposited state which is only 0.27 μΩ cm. The enhancement of AHE is mainly attributed to the interface scattering through post-annealing treatment. - Highlights: • The perpendicular magnetic anisotropy and anomalous Hall effect of Co/Ni multilayer films were studied. • The PMA thermal stability of the Co/Ni ML can be enhanced by HfO{sub 2} capping layer and Pt insertion. • The anomalous Hall resistivity of Co/Ni ML covered by HfO{sub 2} was enhanced by post-annealing treatment.

  7. Interfacial tuning of perpendicular magnetic anisotropy and spin magnetic moment in CoFe/Pd multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ngo, D.-T., E-mail: ndthe82@gmail.com [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Meng, Z.L. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Tahmasebi, T. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, A-STAR (Agency for Science Technology and Research), 5 Engineering Drive 1, Singapore 117608 (Singapore); Yu, X. [Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Thoeng, E. [Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Yeo, L.H. [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Rusydi, A., E-mail: phyandri@nus.edu.sg [Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Han, G.C [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Teo, K.-L., E-mail: eleteokl@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)

    2014-01-15

    We report on a strong perpendicular magnetic anisotropy in [CoFe 0.4 nm/Pd t]{sub 6} (t=1.0–2.0 nm) multilayers fabricated by DC sputtering in an ultrahigh vacuum chamber. Saturation magnetization, M{sub s}, and uniaxial anisotropy, K{sub u}, of the multilayers decrease with increasing the spacing thickness; with a M{sub s} of 155 emu/cc and a K{sub u} of 1.14×10{sup 5} J/m{sup 3} at a spacing thickness of t=2 nm. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements reveal that spin and orbital magnetic moments of Co and Fe in CoFe film decrease as a function of Pd thickness, indicating the major contribution of surface/interfacial magnetism to the magnetic properties of the film. - Highlights: • Strong perpendicular magnetic anisotropy essentially contributed by interfacial anisotropy. • Controllably magnetic properties with low M{sub s}, high K{sub u}, high P. • Interfacial magnetic moments modified by CoFe/Pd interfaces with strong spin–orbit coupling. • Narrow Bloch walls with Néel caps. • Superior magnetic characteristics for spin-torque applications.

  8. NANO-MULTILAYERS WITH HIGH PERPENDICULAR ANISOTROPY FOR MAGNETIC RECORDING

    Institute of Scientific and Technical Information of China (English)

    T. Yang; B.H. Li; K. Kang; T. Suzuki

    2003-01-01

    (FePt/Ag)n nano-multilayers were deposited on MgO (100) single crystal with laser ablation and then subjected to annealing. FePt L1o grains with (001) texture and thus a large perpendicular magnetic anisotropy constant Ku of the order of 106J/m3 were formed. A thick Ag layer is found to be favorable for decreasing the dispersion of the easy axis for magnetization. The measurement of time decay of magnetization gave rise to a small activation volume of the order of 10-25 m3, showing the promising of being the recording medium for future high density perpendicular recording.

  9. Tuning the effective parameters in (Ta/Cu/[Ni/Co]x/Ta) multilayers with perpendicular magnetic anisotropy

    Science.gov (United States)

    Ayareh, Zohreh; Moradi, Mehrdad; Mahmoodi, Saman

    2018-06-01

    In this paper, we report perpendicular magnetic anisotropy (PMA) in a (Ta/Cu/[Ni/Co]x/Ta) multilayers structure. These typical structures usually include a multilayer of ferromagnetic and transition metal thin films. Usually, magnetic anisotropy is characterized by magnetization loops determined by magnetometer or magneto-optical Kerr effect (MOKE). The interface between ferromagnetic and metallic layers plays an important role in magnetic anisotropy evolution from out-of-plane to in-plane in (Ta/Cu/[Ni/Co]/Ta) structure. Obtained results from MOKE and magnetometry of these samples show that they have different easy axes due to change in thickness of Cu as spacer layer and difference in number of repetition of [Ni/Co] stacks.

  10. Interface stress in Au/Ni multilayers

    DEFF Research Database (Denmark)

    Schweitz, K.O.; Böttiger, J.; Chevallier, J.

    2000-01-01

    The effect of intermixing on the apparent interface stress is studied in -textured dc-magnetron sputtered Au/Ni multilayers by use of two methods commonly used for determining interface stress. The method using profilometry and in-plane x-ray diffraction does not take intermixing...... into account and yields an apparent interface stress of -8.46 +/- 0.99 J m(-2). However, observed discrepancies between model calculations and measured high-angle x-ray diffractograms indicate intermixing, and by use of the profilometry and sin(2) psi method the real interface stress value of -2.69 +/- 0.43 J...... m(-2) is found. This method also reveals a significant and systematic change of the stress-free lattice parameter of both constituents as a function of modulation period which is shown to account for the difference between the two findings. The method using in-plane diffraction is thus shown...

  11. Innovative soft magnetic multilayers with enhanced in-plane anisotropy and ferromagnetic resonance frequency for integrated RF passive devices

    Science.gov (United States)

    Falub, Claudiu V.; Bless, Martin; Hida, Rachid; MeduÅa, Mojmír; Ammann, Arnold

    2018-04-01

    We present an innovative, economical method for manufacturing soft magnetic materials that may pave the way for integrated thin film magnetic cores with dramatically improved properties. Soft magnetic multilayered thin films based on the Fe-28%Co20%B (at.%) and Co-4.5%Ta4%Zr (at.%) amorphous alloys are deposited on 8" bare Si and Si/200nm-thermal-SiO2 wafers in an industrial, high-throughput Evatec LLS EVO II magnetron sputtering system. The multilayers consist of stacks of alternating 80-nm-thick ferromagnetic layers and 4-nm-thick Al2O3 dielectric interlayers. Since in our dynamic sputter system the substrate cage rotates continuously, such that the substrates face different targets alternatively, each ferromagnetic sublayer in the multilayer consists of a fine structure comprising alternating CoTaZr and FeCoB nanolayers with very sharp interfaces. We adjust the thickness of these individual nanolayers between 0.5 and 1.5 nm by changing the cage rotation speed and the power of each gun, which is an excellent mode to engineer new, composite ferromagnetic materials. Using X-ray reflectometry (XRR) we reveal that the interfaces between the FeCoB and CoTaZr nanolayers are perfectly smooth with roughness of 0.2-0.3 nm. Kerr magnetometry and B-H looper measurements for the as-deposited samples show that the coercivity of these thin films is very low, 0.2-0.3 Oe, and gradually scales up with the thickness of FeCoB nanolayers, i.e. with the increase of the overall Fe content from 0 % (e.g. CoTaZr-based multilayers) to 52 % (e.g. FeCoB-based multilayers). We explain this trend in the random anisotropy model, based on considerations of grain size growth, as revealed by glancing angle X-ray diffraction (GAXRD), but also because of the increase of magnetostriction with the increase of Fe content as shown by B-H looper measurements performed on strained wafers. The unexpected enhancement of the in-plane anisotropy field from 18.3 Oe and 25.8 Oe for the conventional Co

  12. Perpendicular magnetic anisotropy of amorphous ferromagnetic CoSiB/[Pt,Au] multilayer

    International Nuclear Information System (INIS)

    Jeong, S.; Yim, H. I.

    2012-01-01

    Perpendicular magnetic anisotropy is being widely studied as a possible candidate for a high density spin-transfer torque magnetic random access memory. The key issues of a high-density spin-transfer torque magnetic random access memory are decreasing the switching current and the high thermal stability. In order to solve these problems, two approaches are suggested: One is the development a new amorphous ferromagnetic material as a pinned layer for a multilayer with a low saturated magnetization (M s ) value because of the interface roughness between the two layers. The other is a search for the most suitable materials with high perpendicular magnetic anisotropy in order to have high thermal stability. In this work, we present an amorphous ferromagnetic Co 75 Si 15 B 10 material and compare the magnetic properties of a [CoSiB (0.3, 0.4, 0.5 nm)/Pt (1.4 nm)] 5 multilayer and new combinations [CoSiB (0.3, 0.4, 0.5 nm)/Au (1.5 nm)] 5 .

  13. Recent results on the giant magnetoresistance in magnetic multilayers (anisotropy, thermal variation and CCP-GMR)

    Science.gov (United States)

    Dieny, B.; Granovsky, A.; Vedyaev, A.; Ryzhanova, N.; Cowache, C.; Pereira, L. G.

    1995-12-01

    We present some recent results obtained on the electrical transport properties in magnetic multilayers. Three points are addressed. The first one is an experimental demonstration of the existence of an intrinsic anisotropy of the giant magnetoresistance (GMR). The experiments have been carried out on spin-valve samples for which there is no contribution of the usual anisotropic magnetoresistance to the observed magnetoresistance. The GMR amplitude is found to be larger (lower) in the direction perpendicular (parallel) to the sensing current. The second point concerns a quantitative analysis of the thermal variation of the CIP (current-in-plane) GMR in magnetic multilayers. This analysis is based on a semi-classical theory including the spin-intermixing due to spin-flip scattering by magnons. This approach allows quantitatively evaluation of the respective weights of the various contributions to the thermal decrease in GMR: (i) scattering by magnons in the bulk of the ferromagnetic layers; (ii) phonon scattering in the non-magnetic spacer layer; and (iii) interfacial scattering by paramagnetic interfacial layers which may form as the temperature is increased. The third point is a theoretical investigation of the CPP (current perpendicular to the plane) electrical transport through an interface between two semi-infinite metallic materials. It is shown that when a potential step U exists at such an interface, this step gives rise to an interfacial resistance proportional to U2. It also leads to the existence of large oscillations in the electric fields on both sides of the interface.

  14. Exchange bias energy in Co/Pt/IrMn multilayers with perpendicular and in-plane anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Czapkiewicz, M. [Department of Electronics, AGH University of Science and Technology, 30-059 Cracow (Poland)]. E-mail: czapkiew@agh.edu.pl; Stobiecki, T. [Department of Electronics, AGH University of Science and Technology, 30-059 Cracow (Poland); Rak, R. [Department of Electronics, AGH University of Science and Technology, 30-059 Cracow (Poland); Zoladz, M. [Department of Electronics, AGH University of Science and Technology, 30-059 Cracow (Poland); Dijken, S. van [CRANN and School of Physics, Trinity College, Dublin 2 (Ireland)

    2007-09-15

    The magnetization reversal process in perpendicularly biased [Pt/Co]{sub 3}/d{sub Pt} Pt/IrMn and in-plane biased Co/d{sub Pt} Pt/IrMn multilayers with 0nm=anisotropy, the exchange bias field decreases monotonically with Pt insertion layer thickness, while its coercivity remains constant. The samples with perpendicular magnetic anisotropy, on the other hand, exhibit maximum exchange bias and minimum coercivity for d{sub Pt}=0.1nm. In both cases, the existence of large exchange bias fields correlates with a high domain density during magnetization reversal. The interface exchange coupling energy is larger for the in-plane biased films than for the perpendicularly biased multilayers.

  15. Interfaces anisotropy in single crystal V/Fe/V trilayer

    Energy Technology Data Exchange (ETDEWEB)

    Louis, D. [Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54506 Vandoeuvre-lès-Nancy (France); Lytvynenko, Ia. [Sumy State University, 2, Rymskogo-Korsakova Street, 40007 Sumy (Ukraine); Hauet, T., E-mail: thomas.hauet@univ-lorraine.fr [Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54506 Vandoeuvre-lès-Nancy (France); Lacour, D.; Hehn, M.; Andrieu, S.; Montaigne, F. [Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54506 Vandoeuvre-lès-Nancy (France)

    2014-12-15

    The value and sign of V/Fe interface anisotropy are investigated. Epitaxial V/Fe/V/Au layers with different iron thicknesses were grown on single-crystalline (001) MgO substrate by ultra-high vacuum molecular beam epitaxy. Magnetometry was used to measure magnetization and out-of-plane anisotropy field. From these values, we quantify the number of dead layers due to V/Fe or Fe/V interfaces, and compare it with the literature. We deduce that dead layers occur mostly at the bottom V/Fe interface. An average value for V/Fe and Fe/V interface anisotropy around 0±0.1 erg/cm{sup 2} (mJ/m{sup 2}) was thus deduced. - Highlights: • In a V/Fe/V stack, dead layers (i.e. overall magnetization reduction) originate mostly from the bottom V/Fe interface. • The average value for V/Fe and Fe/V interface anisotropy in V/Fe/V stack has been quantified as 0±0.1 erg/cm{sup 2} (mJ/m{sup 2})

  16. Innovative soft magnetic multilayers with enhanced in-plane anisotropy and ferromagnetic resonance frequency for integrated RF passive devices

    Directory of Open Access Journals (Sweden)

    Claudiu V. Falub

    2018-04-01

    Full Text Available We present an innovative, economical method for manufacturing soft magnetic materials that may pave the way for integrated thin film magnetic cores with dramatically improved properties. Soft magnetic multilayered thin films based on the Fe-28%Co20%B (at.% and Co-4.5%Ta4%Zr (at.% amorphous alloys are deposited on 8” bare Si and Si/200nm-thermal-SiO2 wafers in an industrial, high-throughput Evatec LLS EVO II magnetron sputtering system. The multilayers consist of stacks of alternating 80-nm-thick ferromagnetic layers and 4-nm-thick Al2O3 dielectric interlayers. Since in our dynamic sputter system the substrate cage rotates continuously, such that the substrates face different targets alternatively, each ferromagnetic sublayer in the multilayer consists of a fine structure comprising alternating CoTaZr and FeCoB nanolayers with very sharp interfaces. We adjust the thickness of these individual nanolayers between 0.5 and 1.5 nm by changing the cage rotation speed and the power of each gun, which is an excellent mode to engineer new, composite ferromagnetic materials. Using X-ray reflectometry (XRR we reveal that the interfaces between the FeCoB and CoTaZr nanolayers are perfectly smooth with roughness of 0.2-0.3 nm. Kerr magnetometry and B-H looper measurements for the as-deposited samples show that the coercivity of these thin films is very low, 0.2-0.3 Oe, and gradually scales up with the thickness of FeCoB nanolayers, i.e. with the increase of the overall Fe content from 0 % (e.g. CoTaZr-based multilayers to 52 % (e.g. FeCoB-based multilayers. We explain this trend in the random anisotropy model, based on considerations of grain size growth, as revealed by glancing angle X-ray diffraction (GAXRD, but also because of the increase of magnetostriction with the increase of Fe content as shown by B-H looper measurements performed on strained wafers. The unexpected enhancement of the in-plane anisotropy field from 18.3 Oe and 25.8 Oe for the

  17. Interface alloying in multilayer thin films using polarized neutron reflectometry

    International Nuclear Information System (INIS)

    Basu, Saibal

    2013-01-01

    Polarized Neutron Reflectometry (PNR) is an excellent tool to probe magnetic depth profile in multilayer thin film samples. In case of multilayer films with alternating magnetic and non-magnetic layers, PNR can provide magnetic depth profile at the interfaces with better than nanometer resolution. Using PNR and Xray Reflectometry (XRR) together one can obtain chemical composition and magnetic structure, viz. magnetic moment density at interfaces in multilayer films. We have used these two techniques to obtain kinetics of alloy formation at the interfaces and the magnetic nature of the alloy at the interfaces in several important thin films with magnetic/non-magnetic bilayers. These include Ni/Ti, Ni/Al and Si/Ni pairs. Results obtained from these studies will be presented in this talk. (author)

  18. Anisotropy of heat conduction in Mo/Si multilayers

    International Nuclear Information System (INIS)

    Medvedev, V. V.; Yakshin, A. E.; Kruijs, R. W. E. van de; Bijkerk, F.; Yang, J.; Schmidt, A. J.; Zoethout, E.

    2015-01-01

    This paper reports on the studies of anisotropic heat conduction phenomena in Mo/Si multilayers with individual layer thicknesses selected to be smaller than the mean free path of heat carriers. We applied the frequency-domain thermoreflectance technique to characterize the thermal conductivity tensor. While the mechanisms of the cross-plane heat conduction were studied in detail previously, here we focus on the in-plane heat conduction. To analyze the relative contribution of electron transport to the in-plane heat conduction, we applied sheet-resistance measurements. Results of Mo/Si multilayers with variable thickness of the Mo layers indicate that the net in-plane thermal conductivity depends on the microstructure of the Mo layers

  19. Handling magnetic anisotropy and magnetoimpedance effect in flexible multilayers under external stress

    Energy Technology Data Exchange (ETDEWEB)

    Agra, K.; Bohn, F. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Mori, T.J.A. [Laboratório Nacional de Luz Síncrotron, Rua Giuseppe Máximo Scolfaro, 1000, Guará, 13083-100 Campinas, SP (Brazil); Callegari, G.L.; Dorneles, L.S. [Departamento de Física, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS (Brazil); Correa, M.A., E-mail: marciocorrea@dfte.ufrn.br [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil)

    2016-12-15

    We investigate the dynamic magnetic response though magnetoimpedance effect of ferromagnetic flexible NiFe/Ta and FeCuNbSiB/Ta multilayers under external stress. We explore the possibility of handling magnetic anisotropy, and consequently the magnetoimpedance effect, of magnetostrictive multilayers deposited onto flexible substrates. We quantify the sensitivity of the multilayers under external stress by calculating the ratio between impedance variations and external stress changes, and show that considerable values can be reached by tuning the magnetic field, frequency, magnetostriction constant, and external stress. The results extend possibilities of application of magnetostrictive multilayers deposited onto flexible substrates when under external stress and place them as very attractive candidates as element sensor for the development of sensitive smart touch sensors. - Highlights: • We investigate the magnetoimpedance effect in magnetostrictive flexible multilayers grown on flexible substrates. • The external applied stress enables to tuning the samples anisotropies, and consequently the MI performance. • The flexible substrate becomes promising candidate for RF-frequency devices.

  20. Spin-wave excitation and Moessbauer spectrometry of amorphous interface in Tb/Fe multilayer

    International Nuclear Information System (INIS)

    El Khiraoui, S.; Sajieddine, M.; Lassri, H.; Sahlaoui, M.

    2009-01-01

    Magnetic properties of Tb(48 A)/Fe(26 A) multilayer were studied with Moessbauer spectrometry at different temperatures before and after isothermal annealing at 673 K. For this last case, a significant perpendicular magnetic anisotropy is induced. This phenomenon is related to the existence of an amorphous and homogenous Tb-Fe alloy, located at the interfaces, which is produced by interdiffusion during the heat processing. The thermal evolution of hyperfine field deduced for interfacial Tb-Fe alloy is found to obey the Bloch law. The spin-wave stiffness constant, the distance between nearest magnetic atoms and the exchange parameter A were calculated from the experimental results

  1. Analytical and numerical investigation of double diffusion in thermally anisotropy multilayer porous medium

    Energy Technology Data Exchange (ETDEWEB)

    Bennacer, R. [Neuville sur Oise, LEEVAM 5 mail Gay Lussac, Cergy-Pontoise Cedex (France); Mohamad, A.A. [CEERE University of Calgary, Department of Mechanical and Manufacturing Engineering, Calgary, Alberta (Canada); Ganaoui, M.El [Faculte des Sciences et Techniques de Limoges, Limoges (France)

    2005-02-01

    Double-diffusive natural convection within a multilayer anisotropic porous medium is studied numerically and analytically. The domain composed of two horizontal porous layers is subjected to a uniform horizontal heat flux and a vertical mass flux, where only the lower one is thermally anisotropic. Darcy model with classical Boussinesq approximation is used in formulating the mathematical model. The effect of thermal anisotropy and the relative width of the two layers on the flow and transfers is illustrated with characterising the transitions from the diffusive to the convective solution. Results were well compared with respect to a developed analytical approach, based on a parallel flow approximation for thermally anisotropic multilayer media. (orig.)

  2. Perpendicular magnetic anisotropy and the magnetization process in CoFeB/Pd multilayer films

    DEFF Research Database (Denmark)

    Ngo, Duc-The; Quach, Duy-Truong; Hung, Tran Quang

    2014-01-01

    The perpendicular magnetic anisotropy (PMA) and dynamic magnetization-reversal process in [CoFeB t nm/Pd 1.0 nm]n(t = 0.4, 0.6, 0.8, 1.0 and 1.2 nm; n = 2 − 20) multilayer films have been studied by means of magnetic hysteresis and Kerr effect measurements. Strong and controllable PMA with an eff...

  3. Critical interfaces in geosynthetic multilayer liner system of a landfill

    Directory of Open Access Journals (Sweden)

    Qian Xuede

    2008-12-01

    Full Text Available This study is to identify the critical interface in a geosynthetic multilayer liner system by examining the effects of the interface shear strength of liner components, leachate level, leachate buildup cases, and peak and residual interface strengths. According to current landfill design procedures, conducting stability analysis along the same interface at both the back slope and base may result in a non-conservative result. The critical interfaces with the minimum factor of safety are generally found at different locations along the back slope and base. The critical interface for a multilayer liner system cannot simply be assumed during stability analysis. It can shift from one interface to another with changes in the leachate level and with different leachate buildup cases. The factor of safety for an interface with a high friction angle and low apparent cohesion generally drops much more quickly than it does under inverse conditions when the leachate level increases. The failure interface in a liner system under residual conditions is usually different from the failure interface under peak conditions.

  4. Effects of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers

    KAUST Repository

    Guo, Zaibing

    2012-09-27

    In this paper, we report the results of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers with perpendicular magnetic anisotropy. The surface scattering effect has been extracted from the total anomalous Hall effect. By scaling surface scattering contribution with ρAHs∼ργss, the exponent γ has been found to decrease with the increase of surface scattering resistivity, which could account for the thickness-dependent anomalous Hall effect. Interface diffusion induced by rapid thermal annealing modifies not only the magnetization and longitudinal resistivity but also the anomalous Hall effect; a large exponent γ ∼ 5.7 has been attributed to interface scattering-dominated anomalous Hall effect.

  5. Quantum transport through mesoscopic disordered interfaces, junctions, and multilayers

    International Nuclear Information System (INIS)

    Nikolic, Branislav K.

    2002-01-01

    This study explores perpendicular transport through macroscopically inhomogeneous three-dimensional disordered conductors using mesoscopic methods (the real-space Green function technique in a two-probe measuring geometry). The nanoscale samples (containing ∼ 1000 atoms) are modelled by a tight-binding Hamiltonian on a simple cubic lattice where disorder is introduced in the on-site potential energy. I compute the transport properties of: disordered metallic junctions formed by concatenating two homogeneous samples with different kinds of microscopic disorder, a single strongly disordered interface, and multilayers composed of such interfaces and homogeneous layers characterized by different strengths of the same type of microscopic disorder. This allows us to: contrast the resistor model (semiclassical) approach with a fully quantum description of dirty mesoscopic multilayers; study the transmission properties of dirty interfaces (where the Schep-Bauer distribution of transmission eigenvalues is confirmed for a single interface, as well as for a stack of such interfaces that is thinner than the localization length); and elucidate the effect of coupling to ideal leads ('measuring apparatus') on the conductance of both bulk conductors and dirty interfaces. When a multilayer contains a ballistic layer in between two interfaces, its disorder-averaged conductance oscillates as a function of the Fermi energy. I also address some fundamental issues in quantum transport theory - the relationship between the Kubo formula in the exact state representation and the 'mesoscopic Kubo formula' (which gives the exact zero-temperature conductance of a finite-size sample attached to two semi-infinite ideal leads) is thoroughly re-examined by comparing their outcomes for both the junctions and homogeneous samples. (author)

  6. 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.

  7. Perpendicular magnetic anisotropy and the magnetization process in CoFeB/Pd multilayer films

    International Nuclear Information System (INIS)

    Ngo, Duc-The; Tran, Quang-Hung; Møhave, Kristian; Quach, Duy-Truong; Phan, The-Long; Kim, Dong-Hyun

    2014-01-01

    The perpendicular magnetic anisotropy (PMA) and dynamic magnetization-reversal process in [CoFeB t nm/Pd 1.0 nm] n (t = 0.4, 0.6, 0.8, 1.0 and 1.2 nm; n = 2 − 20) multilayer films have been studied by means of magnetic hysteresis and Kerr effect measurements. Strong and controllable PMA with an effective uniaxial anisotropy up to 7.7 × 10 6  Jm −3 and a saturation magnetization as low as 200 emu cm −3 are achieved. The surface/interfacial anisotropy of the CoFeB/Pd interfaces—the main contribution to the PMA—is separated from the effective uniaxial anisotropy of the films and appears to increase with the number of CoFeB/Pd bilayers. Observation of the magnetic domains during a magnetization-reversal process, using polar magneto-optical Kerr microscopy, reveals the detailed behavior of the nucleation and displacement of the domain walls. (paper)

  8. Multilayer analysis using SIMS: interpretation of profiles at interfaces

    International Nuclear Information System (INIS)

    Aucouturier, M.; Grattepain, C.; Tromson-Carli, A.; Barbe, M.; Cohen-Solal, G.; Marfaing, Y.; Chevrier, F.; Gall, H. le; Imhoff, D.

    1993-01-01

    Secondary ion mass spectrometry (SIMS) is a well adapted analytical method for the chemical characterization of concentration profiles in layered or multilayered materials, particularly concerning the more or less abrupt interfaces bounding those layers. It is known that the fiability and accuracy of the interface characterization may be affected by methodological factors, which alter the depth resolution such as: macroscopical or microscopical initial roughness of the substrate and/or of the layers, ion-induced roughening, effects of differential sputtering of the various elements, transitory stage of the primary ion beam implantation, ion beam induced accelerated diffusion, balistic mixing or segregation; etc.. This communication describes several examples of SIMS analysis performed on metal multilayers (Co/Cu) and on epitaxial semiconductor layers (CdTe/GaAs), focussing the interest on the particular analytical problems raised by the initial roughness and the ion induced roughening effect. The interpretation of the measured profiles, the influence of analytical parameters (such as the nature of the primary ion beam, sputtering conditions, detected ion species), and the limitations of profilometry roughness measurements, are discussed. Solutions are proposed in order to improve the depth resolution of interface characterization, including a tentative modelization of roughness effects. (orig.)

  9. Perpendicular magnetic anisotropy in granular multilayers of CoPd alloyed nanoparticles

    Science.gov (United States)

    Vivas, L. G.; Rubín, J.; Figueroa, A. I.; Bartolomé, F.; García, L. M.; Deranlot, C.; Petroff, F.; Ruiz, L.; González-Calbet, J. M.; Pascarelli, S.; Brookes, N. B.; Wilhelm, F.; Chorro, M.; Rogalev, A.; Bartolomé, J.

    2016-05-01

    Co-Pd multilayers obtained by Pd capping of pre-deposited Co nanoparticles on amorphous alumina are systematically studied by means of high-resolution transmission electron microscopy, x-ray diffraction, extended x-ray absorption fine structure, SQUID-based magnetometry, and x-ray magnetic circular dichroism. The films are formed by CoPd alloyed nanoparticles self-organized across the layers, with the interspace between the nanoparticles filled by the non-alloyed Pd metal. The nanoparticles show atomic arrangements compatible with short-range chemical order of L 10 strucure type. The collective magnetic behavior is that of ferromagnetically coupled particles with perpendicular magnetic anisotropy, irrespective of the amount of deposited Pd. For increasing temperature three magnetic phases are identified: hard ferromagnetic with strong coercive field, soft-ferromagnetic as in an amorphous asperomagnet, and superparamagnetic. Increasing the amount of Pd in the system leads to both magnetic hardness increment and higher transition temperatures. Magnetic total moments of 1.77(4) μB and 0.45(4) μB are found at Co and Pd sites, respectively, where the orbital moment of Co, 0.40(2) μB, is high, while that of Pd is negligible. The effective magnetic anisotropy is the largest in the capping metal series (Pd, Pt, W, Cu, Ag, Au), which is attributed to the interparticle interaction between de nanoparticles, in addition to the intraparticle anisotropy arising from hybridization between the 3 d -4 d bands associated to the Co and Pd chemical arrangement in a L 10 structure type.

  10. Tuning the Magnetic Anisotropy at a Molecule-Metal Interface

    DEFF Research Database (Denmark)

    Bairagi, K.; Bellec, A.; Repain, V.

    2015-01-01

    We demonstrate that a C60 overlayer enhances the perpendicular magnetic anisotropy of a Co thin film, inducing an inverse spin reorientation transition from in plane to out of plane. The driving force is the C60/Co interfacial magnetic anisotropy that we have measured quantitatively in situ...

  11. Lack of dependence between intrinsic magnetic damping and perpendicular magnetic anisotropy in Cu(t{sub Cu})/[Ni/Co]{sub N} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Minghong [Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); Li, Wei [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Ren, Yang [School of Physics and Astronomy, Yunnan University, Kunming 650000 (China); Zhang, Zongzhi, E-mail: zzzhang@fudan.edu.cn [Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); Jin, Q.Y. [Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China)

    2017-04-15

    The correlation between magnetic damping and perpendicular magnetic anisotropy has been investigated in Cu(t{sub Cu})/[Ni/Co]{sub N} multilayers by time-resolved magneto-optical Kerr effect. The uniaxial magnetic anisotropy constant K{sub u} is varied in the range of 3.0–3.6 Merg/cm{sup 3} by tuning either multilayer repetition number N or Cu thickness t{sub Cu}. It is found that the PMA strength K{sub u} increases with the increase of N, while the damping constant α{sub 0} keeps nearly a constant of 0.025, implying the intrinsic damping is independent of the K{sub u} tuned by N. In contrast, as t{sub Cu} increases from 2.5 to 20 nm, the α{sub 0} value rises continuously up to 0.040, in spite of the rather weak enhancement in K{sub u} and its non-monotonic variation behavior. We consider the constant α{sub 0} with N is due to the unchanged spin-orbit coupling strength at each Co/Ni interface, while the obvious enhancement in α{sub 0} with t{sub Cu} results mainly from the increased degree of spin disordering at the rougher Cu/Ni interface. - Highlights: • The perpendicular magnetic anisotropy K{sub u} is tuned in Cu(t{sub Cu})/[Ni/Co]{sub N} system. • The intrinsic magnetic damping is found to be independent K{sub u}. • Extrinsic damping increases with t{sub Cu} due to large interfacial spin disordering.

  12. Interface characterization in B-based multilayer mirrors for next generation lithography

    International Nuclear Information System (INIS)

    Naujok, Philipp; Yulin, Sergiy; Müller, Robert; Kaiser, Norbert; Tünnermann, Andreas

    2016-01-01

    The interfaces in La/B_4C and LaN/B_4C multilayer mirrors designed for near normal incidence reflection of 6.x nm EUV light were investigated by grazing incidence X-ray reflectometry, high-resolution transmission electron microscopy and EUV reflectometry. The thickness and roughness asymmetries of the different interfaces in both studied systems have been identified. A development of interface roughness with an increasing number of bilayers was found by different investigation methods. For near normal incidence, R = 51.1% @ λ = 6.65 nm could be reached with our La/B_4C multilayer mirrors, whereas R = 58.1% was achieved with LaN/B_4C multilayers at the same wavelength. - Highlights: • Interface structure in B-based multilayer mirrors investigated. • Combining X-ray reflection, EUV reflection and transmission electron microscopy • Interface thickness and roughness asymmetry identified • Interface roughness increases with higher number of bilayers.

  13. Anisotropy and vortex behaviour in BiSrCaCuO thin films and multilayers probed by columnar pinning centers

    International Nuclear Information System (INIS)

    Raffy, H.; Murrills, C.D.; Pomar, A.; Stiufiuc, G.; Stiufiuc, R.; Li, Z.Z.

    2006-01-01

    In this paper we review typical mixed state transport results obtained on a variety of Bi 2 Sr 2 Ca n-1 Cu n O y thin films and artificial multilayers, which allowed us to cover the range from low to high anisotropy. The vortex behaviour, 2D or 3D, probed by the pinning properties of columnar defects, is shown to be highly dependant on the anisotropy, and therefore on the microstructure of the system. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  14. Ferromagnetic resonance linewidth and damping in perpendicular-anisotropy magnetic multilayers thin films

    Science.gov (United States)

    Beaujour, Jean-Marc

    2010-03-01

    Transition metal ferromagnetic films with perpendicular magnetic anisotropy (PMA) have ferromagnetic resonance (FMR) linewidths that are one order of magnitude larger than soft magnetic materials, such as pure iron (Fe) and permalloy (NiFe) thin films. We have conducted systematic studies of a variety of thin film materials with perpendicular magnetic anisotropy to investigate the origin of the enhanced FMR linewidths, including Ni/Co and CoFeB/Co/Ni multilayers. In Ni/Co multilayers the PMA was systematically reduced by irradiation with Helium ions, leading to a transition from out-of-plane to in-plane easy axis with increasing He ion fluence [1,2]. The FMR linewidth depends linearly on frequency for perpendicular applied fields and increases significantly when the magnetization is rotated into the film plane with an applied in-plane magnetic field. Irradiation of the film with Helium ions decreases the PMA and the distribution of PMA parameters, leading to a large reduction in the FMR linewidth for in-plane magnetization. These results suggest that fluctuations in the PMA lead to a large two magnon scattering contribution to the linewidth for in-plane magnetization and establish that the Gilbert damping is enhanced in such materials (α˜0.04, compared to α˜0.002 for pure Fe) [2]. We compare these results to those on CoFeB/Co/Ni and published results on other thin film materials with PMA [e.g., Ref. 3]. [1] D. Stanescu et al., J. Appl. Phys. 103, 07B529 (2008). [2] J-M. L. Beaujour, D. Ravelosona, I. Tudosa, E. Fullerton, and A. D. Kent, Phys. Rev. B RC 80, 180415 (2009). [3] N. Mo, J. Hohlfeld, M. ulIslam, C. S. Brown, E. Girt, P. Krivosik, W. Tong, A. Rebel, and C. E. Patton, Appl. Phys. Lett. 92, 022506 (2008). *Research done in collaboration with: A. D. Kent, New York University, D. Ravelosona, Institut d'Electronique Fondamentale, UMR CNRS 8622, Universit'e Paris Sud, E. E. Fullerton, Center for Magnetic Recording Research, UCSD, and supported by NSF

  15. Exchange bias energy in Co/Pt/IrMn multilayers with perpendicular and in-plane anisotropy

    International Nuclear Information System (INIS)

    Czapkiewicz, M.; Stobiecki, T.; Rak, R.; Zoladz, M.; Dijken, S. van

    2007-01-01

    The magnetization reversal process in perpendicularly biased [Pt/Co] 3 /d Pt Pt/IrMn and in-plane biased Co/d Pt Pt/IrMn multilayers with 0nm= Pt = Pt =0.1nm. In both cases, the existence of large exchange bias fields correlates with a high domain density during magnetization reversal. The interface exchange coupling energy is larger for the in-plane biased films than for the perpendicularly biased multilayers

  16. Molecular dynamics simulation of effects of twin interfaces on Cu/Ni multilayers

    International Nuclear Information System (INIS)

    Fu, Tao; Peng, Xianghe; Weng, Shayuan; Zhao, Yinbo; Gao, Fengshan; Deng, Lijun; Wang, Zhongchang

    2016-01-01

    We perform molecular dynamics simulation of the indentation on pure Cu and Ni films and Cu/Ni multilayered films with a cylindrical indenter, aimed to investigate the effects of the cubic-on-cubic interface and hetero-twin interface on their mechanical properties. We also investigate systematically the formation of twin boundary in the pure metals and the effects of the cubic-on-cubic and hetero-twin interface on mechanical properties of the multilayers. We find that the slip of the horizontal stacking fault can release the internal stress, resulting in insignificant strengthening. The change in the crystal orientation by horizontal movement of the atoms in a layer-by-layer manner is found to initiate the movement of twin boundary, and the hetero-twin interface is beneficial to the hardening of multilayers. Moreover, we also find that increasing number of hetero-twin interfaces can harden the Cu/Ni multilayers.

  17. Multivalent-Counterion-Induced Surfactant Multilayer Formation at Hydrophobic and Hydrophilic Solid-Solution Interfaces.

    Science.gov (United States)

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun; Xu, Hui; Tucker, Ian M; Petkov, Jordan T; Sivia, Devinderjit S

    2015-06-23

    Surface multilayer formation from the anionic-nonionic surfactant mixture of sodium dodecyl dioxyethylene sulfate, SLES, and monododecyl dodecaethylene glycol, C12E12, by the addition of multivalent Al(3+) counterions at the solid-solution interface is observed and characterized by neutron reflectivity, NR. The ability to form surface multilayer structures on hydrophobic and hydrophilic silica and cellulose surfaces is demonstrated. The surface multilayer formation is more pronounced and more well developed on the hydrophilic and hydrophobic silica surfaces than on the hydrophilic and hydrophobic cellulose surfaces. The less well developed multilayer formation on the cellulose surfaces is attributed to the greater surface inhomogeneities of the cellulose surface which partially inhibit lateral coherence and growth of the multilayer domains at the surface. The surface multilayer formation is associated with extreme wetting properties and offers the potential for the manipulation of the solid surfaces for enhanced adsorption and control of the wetting behavior.

  18. Exchange bias and perpendicular anisotropy study of ultrathin Pt-Co-Pt-IrMn multilayers sputtered on float glass

    Science.gov (United States)

    Laval, M.; Lüders, U.; Bobo, J. F.

    2007-09-01

    We have prepared ultrathin Pt-Co-Pt-IrMn polycrystalline multilayers on float-glass substrates by DC magnetron sputtering. We have determined the optimal set of thickness for both Pt layers, the Co layer and the IrMn biasing layer so that these samples exhibit at the same time out-of-plane magnetic anisotropy and exchange bias. Kerr microscopy domain structure imaging evidences an increase of nucleation rate accompanied with inhomogeneous magnetic behavior in the case of exchange-biased films compared to Pt-Co-Pt trilayers. Polar hysteresis loops are measured in obliquely applied magnetic field conditions, allowing us to determine both perpendicular anisotropy effective constant Keff and exchange-bias coupling JE, which are significantly different from the ones determined by standard switching field measurements.

  19. Exchange bias and perpendicular anisotropy study of ultrathin Pt-Co-Pt-IrMn multilayers sputtered on float glass

    International Nuclear Information System (INIS)

    Laval, M.; Lueders, U.; Bobo, J.F.

    2007-01-01

    We have prepared ultrathin Pt-Co-Pt-IrMn polycrystalline multilayers on float-glass substrates by DC magnetron sputtering. We have determined the optimal set of thickness for both Pt layers, the Co layer and the IrMn biasing layer so that these samples exhibit at the same time out-of-plane magnetic anisotropy and exchange bias. Kerr microscopy domain structure imaging evidences an increase of nucleation rate accompanied with inhomogeneous magnetic behavior in the case of exchange-biased films compared to Pt-Co-Pt trilayers. Polar hysteresis loops are measured in obliquely applied magnetic field conditions, allowing us to determine both perpendicular anisotropy effective constant K eff and exchange-bias coupling J E , which are significantly different from the ones determined by standard switching field measurements

  20. Nitridation and contrast of B4C/La interfaces and X-ray multilayer optics

    NARCIS (Netherlands)

    Tsarfati, T.; van de Kruijs, Robbert Wilhelmus Elisabeth; Zoethout, E.; Bijkerk, Frederik

    2010-01-01

    Chemical diffusion and interlayer formation in thin layers and at interfaces is of increasing influence in nanoscopic devices such as nano-electronics, magneto-optical storage and multilayer X-ray optics. We show that with the nitridation of reactive B4C/La interfaces, both the chemical and optical

  1. Interface-engineered spin-dependent transport in perpendicular Co/Pt multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Shao-Long; Yang, Guang; Teng, Jiao, E-mail: tengjiao@mater.ustb.edu.cn; Guo, Qi-Xun; Li, Lei-Lei; Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn

    2016-11-30

    Highlights: • The anomalous Hall effect in Co/Pt multilayers is studied. • Thermally stable AHE feature is obtained in [Pt/Co]{sub 3}/Ta/MgO multilayers. • Good thermal stability is due to enhanced side-jump and intrinsic contributions. - Abstract: The improvement of anomalous Hall effect (AHE) has been obtained through the introduction of a Ta metallic layer at the Co/MgO interface in perpendicular [Pt/Co]{sub 3}/MgO multilayers. It is exhibited that the saturation anomalous Hall resistivity is 42% larger than that in Co/Pt multilayers without Ta insertion. More meaningfully, thermally stable AHE feature is gained in perpendicular [Pt/Co]{sub 3}/Ta/MgO multilayers despite Co-Pt interdiffusion. The AHE is enhanced for sample [Pt/Co]{sub 3}/Ta/MgO after annealing, mainly due to the enhancement of the side-jump and intrinsic contributions.

  2. Exploring interface morphology of a deeply buried layer in periodic multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Das, Gangadhar; Srivastava, A. K.; Tiwari, M. K., E-mail: mktiwari@rrcat.gov.in [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013, Madhya Pradesh (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai-400094, Maharashtra (India); Khooha, Ajay; Singh, A. K. [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013, Madhya Pradesh (India)

    2016-06-27

    Long-term durability of a thin film device is strongly correlated with the nature of interface structure associated between different constituent layers. Synthetic periodic multilayer structures are primarily employed as artificial X-ray Bragg reflectors in many applications, and their reflection efficiency is predominantly dictated by the nature of the buried interfaces between the different layers. Herein, we demonstrate the applicability of the combined analysis approach of the X-ray reflectivity and grazing incidence X-ray fluorescence measurements for the reliable and precise determination of a buried interface structure inside periodic X-ray multilayer structures. X-ray standing wave field (XSW) generated under Bragg reflection condition is used to probe the different constituent layers of the W- B{sub 4}C multilayer structure at 10 keV and 12 keV incident X-ray energies. Our results show that the XSW assisted fluorescence measurements are markedly sensitive to the location and interface morphology of a buried layer structure inside a periodic multilayer structure. The cross sectional transmission electron microscopy results obtained on the W-B{sub 4}C multilayer structure provide a deeper look on the overall reliability and accuracy of the XSW method. The method described here would also be applicable for nondestructive characterization of a wide range of thin film based semiconductor and optical devices.

  3. Influence of nanocrystal growth kinetics on interface roughness in nickel-aluminum multilayers

    International Nuclear Information System (INIS)

    Aurongzeb, D.; Holtz, M.; Daugherty, M.; Berg, J.M.; Chandolu, A.; Yun, J.; Temkin, H.

    2003-01-01

    We study the layer morphology of Ni/Al multilayer structures, with 50 nm period, as deposited and following 10 min anneals up through the melting temperature of Al. X-ray reflectivity measurement of the as-deposited film shows interference fringes, characteristic of a well-defined multilayer stack, with ∼1 nm interface roughness. Over a narrow anneal range of 360-500 deg. C these fringes diminish in amplitude and disappear, indicating elevated interface roughening. However, fringes are observed for anneal temperatures both below and above this range, indicating the presence of well-defined layers with smooth interfaces. A model, in which nanocrystal domains of intermetallic nickel aluminides form at the interfaces, is developed to quantify the annealing induced interface roughness. This model agrees well with the experimental results

  4. Cr/B{sub 4}C multilayer mirrors: Study of interfaces and X-ray reflectance

    Energy Technology Data Exchange (ETDEWEB)

    Burcklen, C.; Meltchakov, E.; Jérome, A.; Rossi, S. de; Delmotte, F. [Laboratoire Charles Fabry, Institut d' Optique Graduate School, CNRS, Université Paris-Saclay, 91127 Palaiseau Cedex (France); Soufli, R. [Laboratoire Charles Fabry, Institut d' Optique Graduate School, CNRS, Université Paris-Saclay, 91127 Palaiseau Cedex (France); Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Dennetiere, D.; Polack, F.; Capitanio, B.; Thomasset, M. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, BP 48F-91192 Gif sur Yvette Cedex (France); Gullikson, E. [Center for X-ray Optics, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720 (United States)

    2016-03-28

    We present an experimental study of the effect of layer interfaces on the x-ray reflectance in Cr/B{sub 4}C multilayer interference coatings with layer thicknesses ranging from 0.7 nm to 5.4 nm. The multilayers were deposited by magnetron sputtering and by ion beam sputtering. Grazing incidence x-ray reflectometry, soft x-ray reflectometry, and transmission electron microscopy reveal asymmetric multilayer structures with a larger B{sub 4}C-on-Cr interface, which we modeled with a 1–1.5 nm thick interfacial layer. Reflectance measurements in the vicinity of the Cr L{sub 2,3} absorption edge demonstrate fine structure that is not predicted by simulations using the currently tabulated refractive index (optical constants) values for Cr.

  5. Determination of the electronic density of states near buried interfaces: Application to Co/Cu multilayers

    DEFF Research Database (Denmark)

    Nilsson, A.; Sthör, J.; Wiell, T.

    1996-01-01

    High-resolution L(3) x-ray absorption and emission spectra of Co and Cu in Co/Cu multilayers are shown to provide unique information on the occupied and unoccupied density of d states near buried interfaces. The d bands of both Co and Cu interfacial layers are shown to be considerably narrowed...

  6. Exchange coupling in hybrid anisotropy magnetic multilayers quantified by vector magnetometry

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, C., E-mail: C.Morrison.2@warwick.ac.uk; Miles, J. J.; Thomson, T. [School of Computer Science, University of Manchester, Manchester M13 9PL (United Kingdom); Anh Nguyen, T. N. [Materials Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Spintronics Research Group, Laboratory for Nanotechnology (LNT), VNU-HCM, Ho Chi Minh City (Viet Nam); Fang, Y.; Dumas, R. K. [Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden); Åkerman, J. [Materials Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden)

    2015-05-07

    Hybrid anisotropy thin film heterostructures, where layers with perpendicular and in-plane anisotropy are separated by a thin spacer, are novel materials for zero/low field spin torque oscillators and bit patterned media. Here, we report on magnetization reversal and exchange coupling in a archetypal Co/Pd (perpendicular)-NiFe (in-plane) hybrid anisotropy system studied using vector vibrating sample magnetometry. This technique allows us to quantify the magnetization reversal in each individual magnetic layer, and measure of the interlayer exchange as a function of non-magnetic spacer thickness. At large (>1 nm) spacer thicknesses Ruderman-Kittel-Kasuya-Yosida-like exchange dominates, with orange-peel coupling providing a significant contribution only for sub-nm spacer thickness.

  7. Precise in situ etch depth control of multilayered III−V semiconductor samples with reflectance anisotropy spectroscopy (RAS equipment

    Directory of Open Access Journals (Sweden)

    Ann-Kathrin Kleinschmidt

    2016-11-01

    Full Text Available Reflectance anisotropy spectroscopy (RAS equipment is applied to monitor dry-etch processes (here specifically reactive ion etching (RIE of monocrystalline multilayered III–V semiconductors in situ. The related accuracy of etch depth control is better than 16 nm. Comparison with results of secondary ion mass spectrometry (SIMS reveals a deviation of only about 4 nm in optimal cases. To illustrate the applicability of the reported method in every day settings for the first time the highly etch depth sensitive lithographic process to form a film lens on the waveguide ridge of a broad area laser (BAL is presented. This example elucidates the benefits of the method in semiconductor device fabrication and also suggests how to fulfill design requirements for the sample in order to make RAS control possible.

  8. Analysis of buried interfaces in multilayer mirrors using grazing incidence extreme ultraviolet reflectometry near resonance edges.

    Science.gov (United States)

    Sertsu, M G; Nardello, M; Giglia, A; Corso, A J; Maurizio, C; Juschkin, L; Nicolosi, P

    2015-12-10

    Accurate measurements of optical properties of multilayer (ML) mirrors and chemical compositions of interdiffusion layers are particularly challenging to date. In this work, an innovative and nondestructive experimental characterization method for multilayers is discussed. The method is based on extreme ultraviolet (EUV) reflectivity measurements performed on a wide grazing incidence angular range at an energy near the absorption resonance edge of low-Z elements in the ML components. This experimental method combined with the underlying physical phenomenon of abrupt changes of optical constants near EUV resonance edges enables us to characterize optical and structural properties of multilayers with high sensitivity. A major advantage of the method is to perform detailed quantitative analysis of buried interfaces of multilayer structures in a nondestructive and nonimaging setup. Coatings of Si/Mo multilayers on a Si substrate with period d=16.4  nm, number of bilayers N=25, and different capping structures are investigated. Stoichiometric compositions of Si-on-Mo and Mo-on-Si interface diffusion layers are derived. Effects of surface oxidation reactions and carbon contaminations on the optical constants of capping layers and the impact of neighboring atoms' interactions on optical responses of Si and Mo layers are discussed.

  9. The Interface Influence in TiN/SiN x Multilayer Nanocomposite Under Irradiation

    Science.gov (United States)

    Uglov, V. V.; Safronov, I. V.; Kvasov, N. T.; Remnev, G. E.; Shimanski, V. I.

    2018-01-01

    The paper focuses on studying the kinetics of radiation-induced point defects formed in TiN/SiN x multilayer nanocomposites with account of their generation, diffusion recombination, and the influence of sinks functioning as interfaces. In order to describe the kinetics in nanocrystalline TiN and amorphous SiN x phases, a finite-difference method is used to solve the system of balance kinetic equations for absolute defect concentrations depending on the spatiotemporal variables. A model of the disclination-dislocation interface structure is used to study the absorption of radiation-induced point defects on the boundaries in created stress fields. It is shown that the interface effectively absorbs point defects in these phases of TiN/SiN x multilayer nanocomposite, thereby reducing their amount within the space between phases. This behavior of point defects partially explains a mechanism of the radiation resistance in this type of nanocomposites.

  10. Extracting interface locations in multilayer polymer waveguide films using scanning angle Raman spectroscopy

    International Nuclear Information System (INIS)

    Bobbitt, Jonathan M.; Smith, Emily A.

    2017-01-01

    There is an increasing demand for nondestructive in situ techniques that measure chemical content, total thickness, and interface locations for multilayer polymer films, and SA Raman spectroscopy in combination with appropriate data models can provide this information. A scanning angle (SA) Raman spectroscopy method was developed to measure the chemical composition of multilayer polymer waveguide films and to extract the location of buried interfaces between polymer layers with 7–80-nm axial spatial resolution. The SA Raman method measures Raman spectra as the incident angle of light upon a prism-coupled thin film is scanned. Six multilayer films consisting of poly(methyl methacrylate)/polystyrene or poly(methyl methacrylate)/polystyrene/poly(methyl methacrylate) were prepared with total thicknesses ranging from 330-1260 nm. The interface locations were varied by altering the individual layer thicknesses between 140-680 nm. The Raman amplitude ratio of the 1605 cm -1 peak for PS and 812 cm -1 peak for PMMA was used in calculations of the electric field intensity within the polymer layers to model the SA Raman data and extract the total thickness and interface locations. There is an average 8% and 7% difference in the measured thickness between the SA Raman and profilometry measurements for bilayer and trilayer films, respectively.

  11. Perpendicular magnetic anisotropy in Mo/Co2FeAl0.5Si0.5/MgO/Mo multilayers with optimal Mo buffer layer thickness

    Science.gov (United States)

    Saravanan, L.; Raja, M. Manivel; Prabhu, D.; Pandiyarasan, V.; Ikeda, H.; Therese, H. A.

    2018-05-01

    Perpendicular Magnetic Anisotropy (PMA) was realized in as-deposited Mo(10)/Co2FeAl0.5Si0.5(CFAS)(3)/MgO(0.5)/Mo multilayer stacks with large perpendicular magnetic anisotropy energy (Keff). PMA of this multilayer is found to be strongly dependent on the thickness of the individual CFAS (tCFAS), Mo (tMo) and MgO (tMgO) layers and annealing temperatures. The interactions at the Mo/CFAS/MgO interfaces are critical to induce PMA and are tuned by the interfacial oxidation. The major contribution to PMA is due to iron oxide at the CFAS/MgO interface. X-ray diffraction (XRD) and infrared spectroscopic (FT-IR) studies further ascertain this. However, an adequate oxidation of MgO and the formation of (0 2 4) and (0 1 8) planes of α-Fe2O3 at the optimal Mo buffer layer thickness is mainly inducing PMA in Mo/CFAS/MgO/Mo stack. Microstructural changes in the films are observed by atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) demonstrates the oxidation of CFAS/MgO interface and the formation of Fe-O bonds confirming that the real origin of PMA in Mo/CFAS/MgO is due to hybridization of Fe (3dz2) and O (2pz) orbitals and the resulted spin-orbit interaction at their interface. The half-metallic nature CFAS with Mo layer exhibiting PMA can be a potential candidate as p-MTJs electrodes for the new generation spintronic devices.

  12. Role of anisotropy in determining stability of electrodeposition at solid-solid interfaces

    Science.gov (United States)

    Ahmad, Zeeshan; Viswanathan, Venkatasubramanian

    2017-10-01

    We investigate the stability of electrodeposition at solid-solid interfaces for materials exhibiting an anisotropic mechanical response. The stability of electrodeposition or resistance to the formation of dendrites is studied within a linear stability analysis. The deformation and stress equations are solved using the Stroh formalism and faithfully recover the boundary conditions at the interface. The stability parameter is used to quantify the stability of different solid-solid interfaces incorporating the full anisotropy of the elastic tensor of the two materials. Results show a high degree of variability in the stability parameter depending on the crystallographic orientation of the solids in contact, and point to opportunities for exploiting this effect in developing Li metal anodes.

  13. Magnetic anisotropy and magnetoresistance in Co-based multilayers: a polarised neutron reflectivity study

    International Nuclear Information System (INIS)

    Yusuf, S.M.

    2000-01-01

    We have studied giant magnetoresistance (GMR) and anisotropic magnetoresistance (AMR) effects by carrying out magnetization, magnetoresistance and polarized neutron reflectivity measurements on epitaxial Co/Re multilayers. Polarized neutron reflectivity study with polarization analysis gives a direct way to sense the direction of sublattice magnetization and coupling between magnetic layers. The evolution of magnetic structure as a function of the strength and direction of the applied magnetic field has been studied. The AMR effect observed in magnetoresistance study has been explained in the light of observed magnetic structure. (author)

  14. Preparation of multilayered nanocrystalline thin films with composition-modulated interfaces

    International Nuclear Information System (INIS)

    Biro, D.; Barna, P.B.; Szekely, L.; Geszti, O.; Hattori, T.; Devenyi, A.

    2008-01-01

    The properties of multilayer thin film structures depend on the morphology and structure of interfaces. A broad interface, in which the composition is varying, can enhance, e.g., the hardness of multilayer thin films. In the present experiments multilayers of TiAlN and CrN as well as TiAlN, CrN and MoS 2 were studied by using unbalanced magnetron sputter sources. The sputter sources were arranged side by side on an arc. This arrangement permits development of a transition zone between the layers, where the composition changes continuously. The multilayer system was deposited by one-fold oscillating movement of substrates in front of sputter sources. Thicknesses of layers could be changed both by oscillation frequency and by the power applied to sputter sources. Ti/Al: 50/50 at%, pure chromium and MoS 2 targets were used in the sputter sources. The depositions were performed in an Ar-N 2 mixture at 0.22 Pa working pressure. The sputtering power of the TiAl source was feed-back adjusted in fuzzy-logic mode in order to avoid fluctuation of the TiAl target sputter rate due to poisoning of the target surface. Structure characterization of films deposited on Si wafers covered by thermally grown SiO 2 was performed by cross-sectional transmission electron microscopy. At first a 100 nm thick Cr base layer was deposited on the substrate to improve adhesion, which was followed by a CrN transition layer. The CrN transition layer was followed by a 100 nm thick TiAlN/CrN multilayer system. The TiAlN/CrN/MoS 2 multilayer system was deposited on the surface of this underlayer system. The underlayer systems Cr, CrN and TiAlN/CrN were crystalline with columnar structure according to the morphology of zone T of the structure zone models. The column boundaries contained segregated phases showing up in the under-focused TEM images. The surface of the underlayer system was wavy due to dome-shaped columns. The nanometer-scaled TiAlN/CrN/MoS 2 multilayer system followed this waviness

  15. Structure Transformation and Coherent Interface in Large Lattice-Mismatched Nanoscale Multilayers

    Directory of Open Access Journals (Sweden)

    J. Y. Xie

    2013-01-01

    Full Text Available Nanoscale Al/W multilayers were fabricated by DC magnetron sputtering and characterized by transmission electron microscopy and high-resolution electron microscopy. Despite the large lattice mismatch and significantly different lattice structures between Al and W, a structural transition from face-centered cubic to body-centered cubic in Al layers was observed when the individual layer thickness was reduced from 5 nm to 1 nm, forming coherent Al/W interfaces. For potential mechanisms underlying the observed structure transition and forming of coherent interfaces, it was suggested that the reduction of interfacial energy and high stresses induced by large lattice-mismatch play a crucial role.

  16. NiO/Fe(001): Magnetic anisotropy, exchange bias, and interface structure

    Energy Technology Data Exchange (ETDEWEB)

    Mlynczak, E. [Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow (Poland); Luches, P. [S3, Istituto Nanoscienze-CNR, Via G. Campi 213/a, I-41125 Modena (Italy); Valeri, S. [S3, Istituto Nanoscienze-CNR, Via G. Campi 213/a, I-41125 Modena (Italy); Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Universita di Modena e Reggio Emilia, Via G. Campi 213/a, 41100 Modena (Italy); Korecki, J. [Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow (Poland); Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al.Mickiewicza 30, 30-059 Krakow (Poland)

    2013-06-21

    The magnetic and structural properties of NiO/Fe epitaxial bilayers grown on MgO(001) were studied using magnetooptic Kerr effect (MOKE) and conversion electron Moessbauer spectroscopy (CEMS). The bilayers were prepared under ultra high vacuum conditions using molecular beam epitaxy with oblique deposition. Two systems were compared: one showing the exchange bias (100ML-NiO/24ML-Fe), ML stands for a monolayer, and another where the exchange bias was not observed (50ML-NiO/50ML-Fe). For both, the magnetic anisotropy was found to be complex, yet dominated by the growth-induced uniaxial anisotropy. The training effect was observed for the 100ML-NiO/24ML-Fe system and quantitatively described using the spin glass model. The composition and magnetic state of the interfacial Fe layers were studied using {sup 57}Fe-CEMS. An iron oxide phase (Fe{sup 3+}{sub 4}Fe{sup 2+}{sub 1}O{sub 7}), as thick as 31 A, was identified at the NiO/Fe interface in the as-deposited samples. The ferrimagnetic nature of the interfacial iron oxide film explains the complex magnetic anisotropy observed in the samples.

  17. Optical anisotropy of non-common-atom quantum wells and dots: effects of interface symmetry reduction

    International Nuclear Information System (INIS)

    Toropov, A.A.; Sorokin, S.V.; Shubina, T.V.; Nekrutkina, O.V.; Solnyshkov, D.D.; Ivanov, S.V.; Waag, A.; Landwehr, G.

    2003-01-01

    We report on the investigations of in-plane optical anisotropy in non-common-atom heterostructures: ZnSe/BeTe perfect quantum wells (QWs) and CdSe/BeTe rough QWs and quantum dots. A noticeable linear polarization of photoluminescence (PL) with respect to the in-plane [1-10] and [110] crystal axes was observed in the ZnSe/BeTe QWs with equivalent ZnTe-type interfaces due to the reduction of QW symmetry, induced by unintentional formation of BeSe chemical bonds at a ''BeTe-ZnSe'' interface. The BeSe bond concentration and, hence, the polarization degree depend on the Te/Be flux ratio during molecular beam epitaxy growth of the samples. Strongly linearly polarized (up to 80%) PL was detected in the CdSe/BeTe structures, evidencing QW-like flat symmetry of the emitting sites of carrier localization. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  18. Characteristics of laser ultrasound interaction with multi-layered dissimilar metals adhesive interface by numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kuanshuang, E-mail: zkuanshuang@buaa.edu.cn [School of Mechanical Engineering and Automation, BeiHang University, Beijing 100191 (China); Collaborative Innovation Center of Advanced Aero-Engine, Beijing 100191 (China); Zhou, Zhenggan; Zhou, Jianghua; Sun, Guangkai [School of Mechanical Engineering and Automation, BeiHang University, Beijing 100191 (China); Collaborative Innovation Center of Advanced Aero-Engine, Beijing 100191 (China)

    2015-10-30

    Highlights: • We investigate laser generated ultrasound in multi-layered adhesive structure. • We find the difference of waveforms with different probe points. • Probe points and frequency range influence characterization of the damage interface. • Reflection coefficients of longitudinal waves can quantify the void defect. - Abstract: The characteristics of laser-generated ultrasonic wave interaction with multi-layered dissimilar metals adhesive interface are investigated by finite element method (FEM). The physical model of laser-generated ultrasonic wave in the multi-layered dissimilar metals adhesive structure is built. The surface temperature evolution with different laser power densities is analyzed to obtain the parameters of pulsed laser with thermoelastic regime. The differences of laser ultrasonic waves with different center frequencies measured at the center of laser irradiation would verify the interfacial features of adhesive structures. The optimum frequency range and probe point would be beneficial for the detection of the small void defect. The numerical results indicate that the different frequency range and probe points would evidently influence the identification and quantitative characterization of the small void defect. The research findings would lay a foundation for testing interfacial integrity.

  19. Characteristics of laser ultrasound interaction with multi-layered dissimilar metals adhesive interface by numerical simulation

    International Nuclear Information System (INIS)

    Zhang, Kuanshuang; Zhou, Zhenggan; Zhou, Jianghua; Sun, Guangkai

    2015-01-01

    Highlights: • We investigate laser generated ultrasound in multi-layered adhesive structure. • We find the difference of waveforms with different probe points. • Probe points and frequency range influence characterization of the damage interface. • Reflection coefficients of longitudinal waves can quantify the void defect. - Abstract: The characteristics of laser-generated ultrasonic wave interaction with multi-layered dissimilar metals adhesive interface are investigated by finite element method (FEM). The physical model of laser-generated ultrasonic wave in the multi-layered dissimilar metals adhesive structure is built. The surface temperature evolution with different laser power densities is analyzed to obtain the parameters of pulsed laser with thermoelastic regime. The differences of laser ultrasonic waves with different center frequencies measured at the center of laser irradiation would verify the interfacial features of adhesive structures. The optimum frequency range and probe point would be beneficial for the detection of the small void defect. The numerical results indicate that the different frequency range and probe points would evidently influence the identification and quantitative characterization of the small void defect. The research findings would lay a foundation for testing interfacial integrity.

  20. Enhancement in the interfacial perpendicular magnetic anisotropy and the voltage-controlled magnetic anisotropy by heavy metal doping at the Fe/MgO interface

    Directory of Open Access Journals (Sweden)

    Takayuki Nozaki

    2018-02-01

    Full Text Available We investigated the influence of heavy metal doping at the Fe/MgO interface on the interfacial perpendicular magnetic anisotropy (PMA and the voltage-controlled magnetic anisotropy (VCMA in magnetic tunnel junctions prepared by sputtering-based deposition. The interfacial PMA was increased by tungsten doping and a maximum intrinsic interfacial PMA energy, Ki,0 of 2.0 mJ/m2 was obtained. Ir doping led to a large increase in the VCMA coefficient by a factor of 4.7 compared with that for the standard Fe/MgO interface. The developed technique provides an effective approach to enhancing the interfacial PMA and VCMA properties in the development of voltage-controlled spintronic devices.

  1. Bulk and interface quantum states of electrons in multi-layer heterostructures with topological materials

    Science.gov (United States)

    Nikolic, Aleksandar; Zhang, Kexin; Barnes, C. H. W.

    2018-06-01

    In this article we describe the bulk and interface quantum states of electrons in multi-layer heterostructures in one dimension, consisting of topological insulators (TIs) and topologically trivial materials. We use and extend an effective four-band continuum Hamiltonian by introducing position dependence to the eight material parameters of the Hamiltonian. We are able to demonstrate complete conduction-valence band mixing in the interface states. We find evidence for topological features of bulk states of multi-layer TI heterostructures, as well as demonstrating both complete and incomplete conduction-valence band inversion at different bulk state energies. We show that the linear k z terms in the low-energy Hamiltonian, arising from overlap of p z orbitals between different atomic layers in the case of chalcogenides, control the amount of tunneling from TIs to trivial insulators. Finally, we show that the same linear k z terms in the low-energy Hamiltonian affect the material’s ability to form the localised interface state, and we demonstrate that due to this effect the spin and probability density localisation in a thin film of Sb2Te3 is incomplete. We show that changing the parameter that controls the magnitude of the overlap of p z orbitals affects the transport characteristics of the topologically conducting states, with incomplete topological state localisation resulting in increased backscattering.

  2. Fiber/matrix interfaces for SiC/SiC composites: Multilayer SiC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, H.; Curtin, W.A. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

    1996-08-01

    Tensile tests have been performed on composites of CVI SiC matrix reinforced with 2-d Nicalon fiber cloth, with either pyrolitic carbon or multilayer CVD SiC coatings [Hypertherm High-Temperature Composites Inc., Huntington Beach, CA.] on the fibers. To investigate the role played by the different interfaces, several types of measurements are made on each sample: (i) unload-reload hysteresis loops, and (ii) acoustic emission. The pyrolitic carbon and multilayer SiC coated materials are remarkably similar in overall mechanical responses. These results demonstrate that low-modulus, or compliant, interface coatings are not necessary for good composite performance, and that complex, hierarchical coating structures may possibly yield enhanced high-temperature performance. Analysis of the unload/reload hysteresis loops also indicates that the usual {open_quotes}proportional limit{close_quotes} stress is actually slightly below the stress at which the 0{degrees} load-bearing fibers/matrix interfaces slide and are exposed to atmosphere.

  3. Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling

    Energy Technology Data Exchange (ETDEWEB)

    Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele; Antonio Pignedoli, Carlo; Patscheider, Joerg; Jeurgens, Lars P. H. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Antusek, Andrej [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Faculty of Materials Science and Technology, Slovak University of Technology in Bratislava, Paulinska 16, 917 24 Trnava (Slovakia); Parlinska-Wojtan, Magdalena [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); University of Rzeszow, Institute of Physics, ul. Rejtana 16a, 35-959 Rzeszow (Poland); Bissig, Vinzenz [Kirsten Soldering AG, Hinterbergstrasse 32, CH-6330 Cham (Switzerland)

    2012-10-29

    Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.

  4. Crystalline mono- and multilayer self-assemblies of oligothiophenes at the air-water interface

    DEFF Research Database (Denmark)

    Isz, S.; Weissbuch, I.; Kjær, K.

    1997-01-01

    The formation of Langmuir monolayers at the air-water interface has long been believed to be limited to amphiphilic molecules containing a hydrophobic chain and a hydrophilic headgroup. Here we report the formation of crystalline mono- and multilayer self-assemblies of oligothiophenes, a class...... of aromatic nonamphiphilic molecules, self-aggregated at the air-water interface. As model systems we have examined the deposition of quaterthiophene (S-4), quinquethiophene (S-5). and sexithiophene (S-6) from chloroform solutions on the water surface. The structures of the films were determined by surface...... surface. S-5 self-ageregates at the water surface to form mixtures of monolayers and bilayers of the beta polymorph; S-6 forms primarily crystalline monolayers of both alpha and beta forms. The crystalline assemblies preserve their integrity during transfer from the water surface onto solid supports...

  5. Scaling behavior and morphological properties of the interfaces obtained by the multilayer deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Achik, I. [Laboratoire de Physique de la Matière Condensée, Université Hassan II-Mohammedia, Faculté des sciences Ben M' sik, Casablanca (Morocco); Boughaleb, Y., E-mail: yboughaleb@yahoo.fr [Laboratoire de Physique de la Matière Condensée, Université Hassan II-Mohammedia, Faculté des sciences Ben M' sik, Casablanca (Morocco); Université Chouaib Doukkali, Faculté des sciences, El Jadida (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Hader, A. [Laboratoire de Physique de la Matière Condensée, Université Hassan II-Mohammedia, Faculté des sciences Ben M' sik, Casablanca (Morocco); CRMEF Settat (Morocco); Sbiaai, K. [Université Chouaib Doukkali, Faculté des sciences, El Jadida (Morocco); Hajjaji, A. [Université Chouaib Doukkali, Ecole nationale des sciences appliquées, El Jadida (Morocco)

    2013-10-31

    The aim of the present work was to study numerically the scaling behavior and the morphological properties of the interfaces generated by the multilayer deposition process. We have noticed that, in the case where the ratio of the surface diffusion coefficient to the deposition rate reaches high values D/F > > 1, the interface consists of mound structures. By using the dynamic scaling, we have shown that the height–height correlation function scales with time t and length l as G(l,t) ∼ l{sup α}f(t/l{sup α/β}) with β = 0.25 ± 0.05 and α = 0.51 ± 0.02. These exponent values are equal to the ones predicted by the Edwards–Wilkinson approach. Besides, our results are in agreement with the growth system of Cu/Cu(100) at 300 K which has been characterized in more detail by a combined scanning tunneling microscopy and spot profile analysis — low energy electronic diffusion study. Moreover, by considering two different methods, we have examined the fractal aspect of the obtained interfaces. - Highlights: • The adlayer interfaces present mound morphologies. • The adlayer interfaces scale with the Family–Vicsek law. • The critical exponents (α, β) are in agreement with those of Edwards–Wilkinson approach.

  6. Scaling behavior and morphological properties of the interfaces obtained by the multilayer deposition process

    International Nuclear Information System (INIS)

    Achik, I.; Boughaleb, Y.; Hader, A.; Sbiaai, K.; Hajjaji, A.

    2013-01-01

    The aim of the present work was to study numerically the scaling behavior and the morphological properties of the interfaces generated by the multilayer deposition process. We have noticed that, in the case where the ratio of the surface diffusion coefficient to the deposition rate reaches high values D/F > > 1, the interface consists of mound structures. By using the dynamic scaling, we have shown that the height–height correlation function scales with time t and length l as G(l,t) ∼ l α f(t/l α/β ) with β = 0.25 ± 0.05 and α = 0.51 ± 0.02. These exponent values are equal to the ones predicted by the Edwards–Wilkinson approach. Besides, our results are in agreement with the growth system of Cu/Cu(100) at 300 K which has been characterized in more detail by a combined scanning tunneling microscopy and spot profile analysis — low energy electronic diffusion study. Moreover, by considering two different methods, we have examined the fractal aspect of the obtained interfaces. - Highlights: • The adlayer interfaces present mound morphologies. • The adlayer interfaces scale with the Family–Vicsek law. • The critical exponents (α, β) are in agreement with those of Edwards–Wilkinson approach

  7. Adsorption of the cysteine–tryptophan dipeptide at the Au(110)/liquid interface studied using reflection anisotropy spectroscopy

    DEFF Research Database (Denmark)

    Morozzo della Rocca, Blasco; Smith, C I; Tesauro, Cinzia

    2010-01-01

    The adsorption of a cysteine–tryptophan dipeptide has been monitored at a Au(110)/electrolyte interface using reflection anisotropy spectroscopy. At −0.6 V the dipeptide adsorbed through the formation of Au–S bonds and a link between the NH2 group at the Au surface. As the applied potential...

  8. Effects of HfO{sub 2}/Co interface and Co/HfO{sub 2} interface on anomalous Hall behavior in perpendicular Co/Pt multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Shao-Long [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Yang, Guang [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Teng, Jiao, E-mail: tengjiao@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Guo, Qi-Xun; Liu, Yi-Wei; Li, Xu-Jing [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (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)

    2017-07-01

    Highlights: • Anomalous Hall effect in perpendicular Co/Pt multilayers is studied. • Thermally stable AHE feature is obtained in [Pt/Co]{sub 3}/HfO{sub 2}/Pt multilayers. • Good thermal stability is due to enhanced intrinsic and side-jump contributions. - Abstract: Effects of the HfO{sub 2}/Co interface and the Co/HfO{sub 2} interface on thermal stability of anomalous Hall effect (AHE) in perpendicular Co/Pt multilayers have been studied. It is observed that thermally stable AHE behavior cannot be obtained in perpendicular Co/Pt multilayers with the HfO{sub 2}/Co interface, mainly due to Co-Pt interdiffusion during annealing. In contrast, thermally stable AHE feature is observed in perpendicular Co/Pt multilayers with the Co/HfO{sub 2} interface despite Co-Pt interdiffusion, which is owing to the enhancement of the side jump and intrinsic contributions to the AHE through interfacial modification after annealing.

  9. Optical anisotropy of non-common-atom quantum wells and dots: effects of interface symmetry reduction

    Energy Technology Data Exchange (ETDEWEB)

    Toropov, A.A.; Sorokin, S.V.; Shubina, T.V.; Nekrutkina, O.V.; Solnyshkov, D.D.; Ivanov, S.V. [Ioffe Physico-Technical Institute of RAS, St. Petersburg 194021 (Russian Federation); Waag, A. [Abteilung Halbleiterphysik, Universitaet Ulm, 89081 Ulm (Germany); Landwehr, G. [Physikalisches Institut der Universitaet Wuerzburg, D-97074 Wuerzburg (Germany)

    2003-02-01

    We report on the investigations of in-plane optical anisotropy in non-common-atom heterostructures: ZnSe/BeTe perfect quantum wells (QWs) and CdSe/BeTe rough QWs and quantum dots. A noticeable linear polarization of photoluminescence (PL) with respect to the in-plane [1-10] and [110] crystal axes was observed in the ZnSe/BeTe QWs with equivalent ZnTe-type interfaces due to the reduction of QW symmetry, induced by unintentional formation of BeSe chemical bonds at a ''BeTe-ZnSe'' interface. The BeSe bond concentration and, hence, the polarization degree depend on the Te/Be flux ratio during molecular beam epitaxy growth of the samples. Strongly linearly polarized (up to 80%) PL was detected in the CdSe/BeTe structures, evidencing QW-like flat symmetry of the emitting sites of carrier localization. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  10. Influence of the deposition-induced stress on the magnetic properties of magnetostrictive amorphous (Fe80Co20)80B20 multilayers with orthogonal anisotropy

    International Nuclear Information System (INIS)

    Gonzalez-Guerrero, Miguel; Prieto, Jose Luis; Sanchez, Pedro; Aroca, Claudio

    2007-01-01

    In this work, we experimentally justify that the control of the mechanical stress induced during the deposition of sputtered amorphous magnetostrictive (Fe 80 Co 20 ) 80 B 20 allows a custom design of its magnetic properties. FeCoB multilayers have been sputtered on thermal oxide Si substrates with different buffer materials. The crystalline quality and the thermomechanical properties of the buffer layer influence both the coercive and the anisotropy field. Those buffer layers with both high rigidity and poor thermal conductivity do not allow the dissipation of energy of the incoming sputtered material. Therefore, the mechanical stresses related to the deposition process cannot be released, leading to magnetic layers with high easy-axis coercive field and low anisotropy field. This shows that the mechanical stresses accumulated during deposition are a key parameter for the control of coercivity

  11. Boundary and interface conditions for polarized radiation transport in a multilayer medium

    International Nuclear Information System (INIS)

    Garcia, R.D.M.

    2011-01-01

    In many applications of radiation transport, it is important to consider the changes in the index of refraction that occur when the physical domain being studied consists of material regions with distinct electromagnetic properties. When polarization effects are taken into account, the radiation eld is characterized by a vector of four components known as Stokes vector. At an interface between two different material regions, the reflected and transmitted Stokes vectors are related to the incident Stokes vector by means of reflection and transmission matrices, which are derived from the Fresnel formulas for the amplitude coefficients of reflection and transmission. Having seen that most works on polarized radiation transport that allow for changes in the index of refraction exhibit discrepancies in their expressions for the transmission matrix, we present in this work a careful derivation of the relations between the reflected and transmitted Stokes vectors and the Stokes vector incident on an interface. We obtain a general form of a transmission factor that is required to ensure conservation of energy and we show that most of the discrepancies encountered in existing works are due to the use of improper forms of this factor. In addition, we derive explicit and compact expressions for the Fresnel boundary and interface conditions appropriate to the study of polarized radiation transport in a multilayer medium. (author)

  12. Spin orbit torques and Dzyaloshinskii-Moriya interaction in dual-interfaced Co-Ni multilayers

    KAUST Repository

    Yu, Jiawei; Qiu, Xuepeng; Wu, Yang; Yoon, Jungbum; Deorani, Praveen; Besbas, Jean Mourad; Manchon, Aurelien; Yang, Hyunsoo

    2016-01-01

    We study the spin orbit torque (SOT) and Dzyaloshinskii-Moriya interaction (DMI) in the dual-interfaced Co-Ni perpendicular multilayers. Through the combination of top and bottom layer materials (Pt, Ta, MgO and Cu), SOT and DMI are efficiently manipulated due to an enhancement or cancellation of the top and bottom contributions. However, SOT is found to originate mostly from the bulk of a heavy metal (HM), while DMI is more of interfacial origin. In addition, we find that the direction of the domain wall (DW) motion can be either along or against the electron flow depending on the DW tilting angle when there is a large DMI. Such an abnormal DW motion induces a large assist field required for hysteretic magnetization reversal. Our results provide insight into the role of DMI in SOT driven magnetization switching, and demonstrate the feasibility of achieving desirable SOT and DMI for spintronic devices.

  13. Spin orbit torques and Dzyaloshinskii-Moriya interaction in dual-interfaced Co-Ni multilayers

    KAUST Repository

    Yu, Jiawei

    2016-09-07

    We study the spin orbit torque (SOT) and Dzyaloshinskii-Moriya interaction (DMI) in the dual-interfaced Co-Ni perpendicular multilayers. Through the combination of top and bottom layer materials (Pt, Ta, MgO and Cu), SOT and DMI are efficiently manipulated due to an enhancement or cancellation of the top and bottom contributions. However, SOT is found to originate mostly from the bulk of a heavy metal (HM), while DMI is more of interfacial origin. In addition, we find that the direction of the domain wall (DW) motion can be either along or against the electron flow depending on the DW tilting angle when there is a large DMI. Such an abnormal DW motion induces a large assist field required for hysteretic magnetization reversal. Our results provide insight into the role of DMI in SOT driven magnetization switching, and demonstrate the feasibility of achieving desirable SOT and DMI for spintronic devices.

  14. Modeling of Interface and Internal Disorder Applied to XRD Analysis of Ag-Based Nano-Multilayers.

    Science.gov (United States)

    Ariosa, Daniel; Cancellieri, Claudia; Araullo-Peters, Vicente; Chiodi, Mirco; Klyatskina, Elizaveta; Janczak-Rusch, Jolanta; Jeurgens, Lars P H

    2018-06-07

    Multilayered structures are a promising route to tailor electronic, magnetic, optical, and/or mechanical properties and durability of functional materials. Sputter deposition at room temperature, being an out-of-equilibrium process, introduces structural defects and confers to these nanosystems an intrinsic thermodynamical instability. As-deposited materials exhibit a large amount of internal atomic displacements within each constituent block as well as severe interface roughness between different layers. To access and characterize the internal multilayer disorder and its thermal evolution, X-ray diffraction investigation and analysis are performed systematically at differently grown Ag-Ge/aluminum nitride (AlN) multilayers (co-deposited, sequentially deposited with and without radio frequency (RF) bias) samples and after high-temperature annealing treatment. We report here on model calculations based on a kinematic formalism describing the displacement disorder both within the multilayer blocks and at the interfaces to reproduce the experimental X-ray diffraction intensities. Mixing and displacements at the interface are found to be considerably reduced after thermal treatment for co- and sequentially deposited Ag-Ge/AlN samples. The application of a RF bias during the deposition causes the highest interface mixing and introduces random intercalates in the AlN layers. X-ray analysis is contrasted to transmission electron microscopy pictures to validate the approach.

  15. Influence of boundary conditions on the response of multilayered plates with cohesive interfaces and delaminations using a homogenized approach

    Directory of Open Access Journals (Sweden)

    R. Massabò

    2014-07-01

    Full Text Available Stress and displacement fields in multilayered composites with interfacial imperfections, such as imperfect bonding of the layers or delaminations, or where the plies are separated by thin interlayers allowing relative motion, have large variations in the thickness, with characteristic zigzag patterns and jumps at the layer interfaces. These effects are well captured by a model recently formulated by the author for multilayered plates with imperfect interfaces and affine interfacial traction laws (Massabò & Campi, Meccanica, 2014, in press; Compos Struct, 2014, 116, 311-324. The model defines a homogenized displacement field, which satisfies interfacial continuity, and uses a variational technique to derive equilibrium equations depending on only six generalized displacement functions, for any arbitrary numbers of layers and interfaces. The model accurately predicts stresses and displacements in simply supported, highly anisotropic, thick plates with continuous, sliding interfaces. In this paper the model is applied to wide plates with clamped edges and some inconsistencies, which have been noted in the literature for models based on similar approaches and have limited their utilization, are explained. A generalized transverse shear force is introduced as the gross stress resultant which is directly related to the bending moment in the equilibrium equations of multilayered structures with imperfect interfaces and substitutes for the shear force of single-layer theory. An application to a delaminated wide plate highlights the potential and limitations of the proposed model for the solution of fracture mechanics problems.

  16. Perturbation Theory for Scattering from Multilayers with Randomly Rough Fractal Interfaces: Remote Sensing Applications

    Directory of Open Access Journals (Sweden)

    Pasquale Imperatore

    2017-12-01

    Full Text Available A general, approximate perturbation method, able to provide closed-form expressions of scattering from a layered structure with an arbitrary number of rough interfaces, has been recently developed. Such a method provides a unique tool for the characterization of radar response patterns of natural rough multilayers. In order to show that, here, for the first time in a journal paper, we describe the application of the developed perturbation theory to fractal interfaces; we then employ the perturbative method solution to analyze the scattering from real-world layered structures of practical interest in remote sensing applications. We focus on the dependence of normalized radar cross section on geometrical and physical properties of the considered scenarios, and we choose two classes of natural stratifications: wet paleosoil covered by a low-loss dry sand layer and a sea-ice layer above water with dry snow cover. Results are in accordance with the experimental evidence available in the literature for the low-loss dry sand layer, and they may provide useful indications about the actual ability of remote sensing instruments to perform sub-surface sensing for different sensor and scene parameters.

  17. Perturbation Theory for Scattering from Multilayers with Randomly Rough Fractal Interfaces: Remote Sensing Applications.

    Science.gov (United States)

    Imperatore, Pasquale; Iodice, Antonio; Riccio, Daniele

    2017-12-27

    A general, approximate perturbation method, able to provide closed-form expressions of scattering from a layered structure with an arbitrary number of rough interfaces, has been recently developed. Such a method provides a unique tool for the characterization of radar response patterns of natural rough multilayers. In order to show that, here, for the first time in a journal paper, we describe the application of the developed perturbation theory to fractal interfaces; we then employ the perturbative method solution to analyze the scattering from real-world layered structures of practical interest in remote sensing applications. We focus on the dependence of normalized radar cross section on geometrical and physical properties of the considered scenarios, and we choose two classes of natural stratifications: wet paleosoil covered by a low-loss dry sand layer and a sea-ice layer above water with dry snow cover. Results are in accordance with the experimental evidence available in the literature for the low-loss dry sand layer, and they may provide useful indications about the actual ability of remote sensing instruments to perform sub-surface sensing for different sensor and scene parameters.

  18. Role of Interface in Multilayered Composites under Irradiation: A Mathematical Investigation

    Directory of Open Access Journals (Sweden)

    Jaime Ortún-Palacios

    2017-01-01

    Full Text Available A continuum model of point-defects evolution during irradiation of a multilayer composite material is presented in this work. Nonstationary balance equations are used to describe production, recombination, transport, and annihilation, or removal, of vacancies and interstitials in a β-α-β three-layer system (α = Cu and β = Nb, V, or Ni. In addition, transport and trapping of point-defects at interfaces are taken into account. Numerical investigation on similarities and differences between Cu/Nb, Cu/V, and Cu/Ni systems is also performed. A general comparison of model results reveals that average vacancy concentration is typically higher than SIA one in both layers for all the systems investigated. This is a consequence of the higher diffusion rate of SIAs with respect to vacancies. Stationary state is reached without saturating interface point-defect traps by all systems but Cu/Ni for the case of SIAs. It can be also seen that Cu/Nb and Cu/V systems have a very similar behavior regarding point-defect temporal evolution in copper (layer α, while higher SIA concentration at steady state is shown therein by the Cu/Ni structure. Moreover, Cu/V system displays the lower stationary vacancy concentration in layer β.

  19. ADM guidance-Ceramics: all-ceramic multilayer interfaces in dentistry.

    Science.gov (United States)

    Lohbauer, Ulrich; Scherrer, Susanne S; Della Bona, Alvaro; Tholey, Michael; van Noort, Richard; Vichi, Alessandro; Kelly, J Robert; Cesar, Paulo F

    2017-06-01

    This guidance document describes the specific issues involved in dental multilayer ceramic systems. The material interactions with regard to specific thermal and mechanical properties are reviewed and the characteristics of dental tooth-shaped processing parameters (sintering, geometry, thickness ratio, etc.) are discussed. Several techniques for the measurement of bond quality and residual stresses are presented with a detailed discussion of advantages and disadvantages. In essence no single technique is able to describe adequately the all-ceramic interface. Invasive or semi-invasive methods have been shown to distort the information regarding the residual stress state while non-invasive methods are limited due to resolution, field of focus or working depth. This guidance document has endeavored to provide a scientific basis for future research aimed at characterizing the ceramic interface of dental restorations. Along with the methodological discussion it is seeking to provide an introduction and guidance to relatively inexperienced researchers. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Hetero-Colloidal Metal Particle Multilayer Films Grown Using Electrostatic Interactions at the Air-water Interface

    International Nuclear Information System (INIS)

    Sastry, Murali; Mayya, K.S.

    2000-01-01

    The formation of nanoparticle multilayer films by electrostatic immobilization of surface-modified colloidal particles at the air-water interface has been recently demonstrated by us. In this paper, we extend our study to show that multilayer assemblies consisting of metal particles of different chemical nature (hetero-colloidal particle superlattices) and size can be deposited by the versatile Langmuir-Blodgett technique. Multilayer films consisting of a different number of bilayers of gold and silver colloidal particles have been deposited and characterized using quartz crystal microgravimetry and UV-visible spectroscopy measurements. It is observed that while layer-by-layer deposition of the different colloidal particle assemblies is possible by this technique without a detectable variation in the cluster density in the different layers, a degree of post-deposition reorganization of the clusters occurs in the film. In addition to this aging behavior, the effect of different organic solvents on the reorganization process has also been studied

  1. Exchange bias mechanism in FM/FM/AF spin valve systems in the presence of random unidirectional anisotropy field at the AF interface: The role played by the interface roughness due to randomness

    Science.gov (United States)

    Yüksel, Yusuf

    2018-05-01

    We propose an atomistic model and present Monte Carlo simulation results regarding the influence of FM/AF interface structure on the hysteresis mechanism and exchange bias behavior for a spin valve type FM/FM/AF magnetic junction. We simulate perfectly flat and roughened interface structures both with uncompensated interfacial AF moments. In order to simulate rough interface effect, we introduce the concept of random exchange anisotropy field induced at the interface, and acting on the interface AF spins. Our results yield that different types of the random field distributions of anisotropy field may lead to different behavior of exchange bias.

  2. Chemical interactions at the interfaces of Mo/B4C/Si/B4C multilayers upon low-temperature annealing

    NARCIS (Netherlands)

    Nyabero, S.L.; van de Kruijs, Robbert Wilhelmus Elisabeth; Yakshin, Andrey; Bijkerk, Frederik

    2012-01-01

    Interactions at interfaces in thin films and multilayers play an important role for present day nano-scaled devices. For example, reducing thermally induced interdiffusion between Mo and Si layers is a key challenge in developing Mo/Si multilayers as reflective coatings for projection lithography

  3. Highly (001) oriented L1{sub 0}-CoPt/TiN multilayer films on glass substrates with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    An, Hongyu; Sannomiya, Takumi; Muraishi, Shinji; Nakamura, Yoshio; Shi, Ji, E-mail: shi.j.aa@m.titech.ac.jp [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Xie, Qian; Zhang, Zhengjun [Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wang, Jian [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan)

    2015-03-15

    To obtain strong perpendicular magnetic anisotropy (PMA) based on L1{sub 0} structure for magnetic storage devices, costly single crystalline substrates are generally required to achieve (001) texture. Recently, various studies also have focused on depositing different kinds of seed layers on glass or other amorphous substrates to promote (001) preferred orientation of L1{sub 0} CoPt and FePt. TiN is a very promising seed layer material because of its cubic crystalline structure (similar to MgO) and excellent diffusion barring property even at high temperatures. In the present work, highly (001) oriented L1{sub 0}-CoPt/TiN multilayer films have been successfully deposited on glass substrates. After annealing at 700 °C, the film exhibits PMA, and a strong (001) peak is detected from the x-ray diffraction profiles, indicating the ordering transformation of CoPt layers from fcc (A1) to L1{sub 0} structure. It also is found that alternate deposition of cubic TiN and CoPt effectively improves the crystallinity and (001) preferred orientation of CoPt layers. This effect is verified by the substantial enhancement of (001) reflection and PMA with increasing the period number of the multilayer films.

  4. Modified magnetic anisotropy at LaCoO3/La0.7Sr0.3MnO3 interfaces

    Directory of Open Access Journals (Sweden)

    M. Cabero

    2017-09-01

    Full Text Available Controlling magnetic anisotropy is an important objective towards engineering novel magnetic device concepts in oxide electronics. In thin film manganites, magnetic anisotropy is weak and it is primarily determined by the substrate, through induced structural distortions resulting from epitaxial mismatch strain. On the other hand, in cobaltites, with a stronger spin orbit interaction, magnetic anisotropy is typically much stronger. In this paper, we show that interfacing La0.7Sr0.3MnO3 (LSMO with an ultrathin LaCoO3 (LCO layer drastically modifies the magnetic anisotropy of the manganite, making it independent of the substrate and closer to the magnetic isotropy characterizing its rhombohedral structure. Ferromagnetic resonance measurements evidence a tendency of manganite magnetic moments to point out-of-plane suggesting non collinear magnetic interactions at the interface. These results may be of interest for the design of oxide interfaces with tailored magnetic structures for new oxide devices.

  5. Mechanical performance of Hi-Nicalon/CVI-SiC composites with multilayer SiC/C interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, H.G.; Carter, R.H.; Curtin, W.A. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Engineering Science and Mechanics

    1997-12-01

    The mechanical properties and interfacial characteristics of new SiC/SiC ceramic composites, composed of Hi-Nicalon fibers in a CVI-SiC matrix and having a variety of multilayer SiC/C coatings between the fibers and the matrix, are studied in detail to elucidate the roles of the coatings and fibers. Axial tension tests and unload/reload hysteresis loop measurements are performed to determine mechanical performance. All materials exhibit the strong and tough behavior characteristic of good ceramic composites, with all multilayer variants performing quite similarly. SEM microscopy demonstrates that matrix cracks penetrate through the multilayers and debond at the fiber/inner-coating interface. Analysis of the hysteretic behavior leads to values for interfacial sliding resistance {tau} {approx} 11 ksi and interfacial toughness {Gamma}{sub i} {approx} 2 J/m{sup 2} that are nearly independent of multilayer structure, and are similar to values obtained for standard pyrolitic carbon interfaces. These results all indicate debonding at the fiber surface for all coating structures, which provides a common roughness, {tau}, and {Gamma}{sub i}. Analysis of fiber fracture mirrors provides an estimate of the in-situ strength of the fibers and demonstrates the high strength retention of the Hi-Nicalon fibers. The in-situ fiber strengths are combined with the measured pullout lengths to obtain an independent determination of {tau} = 8.5 ksi that agrees well with the value found from the hysteretic behavior. Predictions of composite strength using the derived fiber strengths agree well with the measured value although the predicted failure strain is too large. This study demonstrates that Hi-Nicalon fiber/CVI-SiC composites perform well for a wide range of multilayer interface structures and that the interfaces present relatively high values of {tau} and {Gamma}{sub i}, both of which are beneficial to strength and toughness. The small carbon layer thicknesses in these multilayer

  6. Complex, multilayered azimuthal anisotropy beneath Tibet: evidence for co-existing channel flow and pure-shear crustal thickening

    Science.gov (United States)

    Agius, Matthew R.; Lebedev, Sergei

    2017-09-01

    Of the two debated, end-member models for the late-Cenozoic thickening of Tibetan crust, one invokes 'channel flow' (rapid viscous flow of the mid-lower crust, driven by topography-induced pressure gradients and transporting crustal rocks eastward) and the other 'pure shear' (faulting and folding in the upper crust, with viscous shortening in the mid-lower crust). Deep-crustal deformation implied by each model is different and would produce different anisotropic rock fabric. Observations of seismic anisotropy can thus offer a discriminant. We use broad-band phase-velocity curves-each a robust average of tens to hundreds of measurements-to determine azimuthal anisotropy in the entire lithosphere-asthenosphere depth range and constrain its amplitude. Inversions of the differential dispersion from path pairs, region-average inversions and phase-velocity tomography yield mutually consistent results, defining two highly anisotropic layers with different fast-propagation directions within each: the middle crust and the asthenosphere. In the asthenosphere beneath central and eastern Tibet, anisotropy is 2-4 per cent and has an NNE-SSW fast-propagation azimuth, indicating flow probably driven by the NNE-ward, shallow-angle subduction of India. The distribution and complexity of published shear wave splitting measurements can be accounted for by the different anisotropy in the mid-lower crust and asthenosphere. The estimated splitting times that would be accumulated in the crust alone are 0.25-0.8 s; in the upper mantle-0.5-1.2 s, depending on location. In the middle crust (20-45 km depth) beneath southern and central Tibet, azimuthal anisotropy is 3-5 and 4-6 per cent, respectively, and its E-W fast-propagation directions are parallel to the current extension at the surface. The rate of the extension is relatively low, however, whereas the large radial anisotropy observed in the middle crust requires strong alignment of mica crystals, implying large finite strain and

  7. Role of interface states on electron transport in a-Si:H/nc-Si:H multilayer structures

    Science.gov (United States)

    Yadav, Asha; Kumari, Juhi; Agarwal, Pratima

    2018-05-01

    In this paper we report, I-V characteristic of a-Si:H/nc-Si:H multilayer structures in lateral as well as transverse direction. In lateral geometry, where the interfaces are parallel to the direction of electronic transport, residual photo conductivity (persistent photoconductivity) is observed after the light was turned off. On the other hand, in transverse geometry, where interfaces are along the direction of electronic transport, the space charge limited currents are affected and higher density of states is obtained. The PPC was more in the structures where numbers of such interface were more. These results have been understood in terms of the charge carriers trapped at the interface, which influence the electronic transport.

  8. Interface Engineering for Precise Threshold Voltage Control in Multilayer-Channel Thin Film Transistors

    KAUST Repository

    Park, Jihoon

    2016-11-29

    Multilayer channel structure is used to effectively manipulate the threshold voltage of zinc oxide transistors without degrading its field-effect mobility. Transistors operating in enhancement mode with good mobility are fabricated by optimizing the structure of the multilayer channel. The optimization is attributed to the formation of additional channel and suppression of the diffusion of absorbed water molecules and oxygen vacancies.

  9. Interface Engineering for Precise Threshold Voltage Control in Multilayer-Channel Thin Film Transistors

    KAUST Repository

    Park, Jihoon; Alshammari, Fwzah Hamud; Wang, Zhenwei; Alshareef, Husam N.

    2016-01-01

    Multilayer channel structure is used to effectively manipulate the threshold voltage of zinc oxide transistors without degrading its field-effect mobility. Transistors operating in enhancement mode with good mobility are fabricated by optimizing the structure of the multilayer channel. The optimization is attributed to the formation of additional channel and suppression of the diffusion of absorbed water molecules and oxygen vacancies.

  10. Recent Developments in the X-Ray Reflectivity Analysis for Rough Surfaces and Interfaces of Multilayered Thin Film Materials

    Directory of Open Access Journals (Sweden)

    Yoshikazu Fujii

    2013-01-01

    Full Text Available X-ray reflectometry is a powerful tool for investigations on rough surface and interface structures of multilayered thin film materials. The X-ray reflectivity has been calculated based on the Parratt formalism, accounting for the effect of roughness by the theory of Nevot-Croce conventionally. However, in previous studies, the calculations of the X-ray reflectivity often show a strange effect where interference effects would increase at a rough surface. And estimated surface and interface roughnesses from the X-ray reflectivity measurements did not correspond to the TEM image observation results. The strange result had its origin in a used equation due to a serious mistake in which the Fresnel transmission coefficient in the reflectivity equation is increased at a rough interface because of a lack of consideration of diffuse scattering. In this review, a new accurate formalism that corrects this mistake is presented. The new accurate formalism derives an accurate analysis of the X-ray reflectivity from a multilayer surface of thin film materials, taking into account the effect of roughness-induced diffuse scattering. The calculated reflectivity by this accurate reflectivity equation should enable the structure of buried interfaces to be analyzed more accurately.

  11. Theoretical comparison of light scattering and guided wave coupling in multilayer coated optical components with random interface roughness

    International Nuclear Information System (INIS)

    Elson, J.M.

    1995-01-01

    In this work, we use first-order perturbation theory to calculate and then compare the (1) angular distribution of incident light scattered from a multilayer-coated optical component and (2) the angular distribution of incident light coupled into guided waves supported by the multilayer component. The incident beam is assumed to be a monochromatic plane wave and the scattering/coupling is assumed to be caused by roughness at the interfaces of the optical component. Numerical results show that for high quality (low root mean square roughness) optical components, comparison of the relative amounts of incident energy (1) scattered out of the specular beam and (2) coupled into guided waves are comparable. It follows that the guided wave energy will further contribute to the scattered field via radiative decay or be converted to heat. Thus, this work can help provide an estimation of when guided wave coupling can occur along with the expected magnitude. (orig.)

  12. Magnetic properties of Dy/Zr multilayers

    International Nuclear Information System (INIS)

    Luche, M.C.; Boyer, P.

    1992-01-01

    [Dy(xA)/Zr(30A)] n superlattices (x ≤ 30), were evaporated under ultra-high vacuum on Si(100) substrates. Magnetization measurements indicate that the antiferromagnetic transition occurring at 178K in bulk Dy is suppressed in the multilayers. This phenomenon is attributed to magnetoelastic effects induced by strains at Zr/Dy interfaces. A perpendicular magnetic anisotropy takes place for x ≤ 15. However, the magnetic anisotropy is found to depend markedly on the technique used for Dy deposition. (author). 11 refs., 4 figs

  13. Magnetic properties and structure of FePt/FeMn multilayers

    International Nuclear Information System (INIS)

    Phuoc, Nguyen N.; Suzuki, Takao

    2007-01-01

    A systematic study of the magnetic properties by ion beam sputter-deposition system, was conducted in conjunction with the structure of FePt/FeMn multilayers fabricated onto MgO(0 0 1) substrates. Both parallel and perpendicular exchange biases were observed in the multilayers and were found to decrease drastically, as the deposition temperature is higher than 350 deg. C, which is evidently due to the interdiffusion at the interface. The thickness dependence study shows that the perpendicular magnetic anisotropy observed in the multilayers originates from surface anisotropy, being consistent with the decrease of perpendicular magnetic anisotropy as the deposition temperature is increased. The difference between parallel and perpendicular blocking temperatures that was clearly observed, is possibly due to the spin canting out of plane at the interface

  14. Interface morphology of Mo/Si multilayer systems with varying Mo layer thickness studied by EUV diffuse scattering.

    Science.gov (United States)

    Haase, Anton; Soltwisch, Victor; Braun, Stefan; Laubis, Christian; Scholze, Frank

    2017-06-26

    We investigate the influence of the Mo-layer thickness on the EUV reflectance of Mo/Si mirrors with a set of unpolished and interface-polished Mo/Si/C multilayer mirrors. The Mo-layer thickness is varied in the range from 1.7 nm to 3.05 nm. We use a novel combination of specular and diffuse intensity measurements to determine the interface roughness throughout the multilayer stack and do not rely on scanning probe measurements at the surface only. The combination of EUV and X-ray reflectivity measurements and near-normal incidence EUV diffuse scattering allows to reconstruct the Mo layer thicknesses and to determine the interface roughness power spectral density. The data analysis is conducted by applying a matrix method for the specular reflection and the distorted-wave Born approximation for diffuse scattering. We introduce the Markov-chain Monte Carlo method into the field in order to determine the respective confidence intervals for all reconstructed parameters. We unambiguously detect a threshold thickness for Mo in both sample sets where the specular reflectance goes through a local minimum correlated with a distinct increase in diffuse scatter. We attribute that to the known appearance of an amorphous-to-crystallization transition at a certain thickness threshold which is altered in our sample system by the polishing.

  15. Influence of Pt thickness on magnetization reversal processes in (Pt/Co)3 multilayers with perpendicular anisotropy

    International Nuclear Information System (INIS)

    Belhi, R.; Adanlété Adjanoh, A.; Vogel, J.

    2012-01-01

    We present a detailed study of the magnetization reversal in perpendicularly magnetized (Pt/Co) 3 multilayers with different values of the platinum interlayer thickness t Pt . To study the magnetization reversal in our samples we combined measurements of relaxation curves with the direct visualization of domain structures. Magnetization reversal was dominated by domain wall propagation for t Pt =1 nm and by domain nucleation for t Pt =0.2 nm, while a mixed process was observed for t Pt =0.8 nm. We interpret our results within the framework of a model of thermally activated reversal where a distribution of activation energy barriers is taken into account. The reversal process was correlated with the energy barrier distribution. - Highlights: ► We show that the coercivity decreases with the Pt interlayer thickness. ► The reversal process is sensitively dependent on platinum interlayer thickness. ► We interpreted the results by taking into account of an energy barrier distribution. ► The reversal process was correlated with the energy barrier distribution width. ► The energy barrier distribution width varies linearly with the applied field.

  16. Effects of oxide replacement with fluoride at the CoFeB interface on interface magnetic anisotropy and its voltage control

    Science.gov (United States)

    Pankieiev, Mykhailo; Kita, Koji

    2018-05-01

    In this paper we report results of improving Co60Fe20B20 interface perpendicular magnetic anisotropy (PMA) by replacing neighbor oxide layer with fluoride one. We expected that fluorine as element with higher than oxide electronegativity could more effectively attract electrons from out-of-plane d orbitals of ferromagnetic, increasing role of in-plane orbitals. By this we wanted to increase PMA and its response to applied voltage bias. Polar magneto-optic Kerr effect measurement show decreasing of out-of-plane magnetic field needed to change magnetization to perpendicular in stacks with oxygen replaced by fluorine as well as increasing of coefficient of response to applied voltage α from < 10 fJ/Vm for CoFeB/Al2O3 interface to 20 fJ/Vm for CoFeB/AlF3/Al2O3 and 22 fJ/Vm for CoFeB/MgF2 stacks. Direct chemical interaction of Co with F was confirmed by x-ray photoelectron spectroscopy (XPS) measurement of Co2p core level region. Moreover angular-resolved XPS showed that F tends to stay at CoFeB interface rather than diffuse out of it.

  17. Origin of Colossal Ionic Conductivity in Oxide Multilayers: Interface Induced Sublattice Disorder

    International Nuclear Information System (INIS)

    Pennycook, Timothy J.; Pantelides, Sokrates T.; Beck, Matthew J.; Varga, Kalman; Varela, Maria; Pennycook, Stephen J.

    2010-01-01

    Oxide ionic conductors typically operate at high temperatures, which limits their usefulness. Colossal room-temperature ionic conductivity was recently discovered in multilayers of yttria-stabilized zirconia (YSZ) and SrTiO 3 . Here we report density-functional calculations that trace the origin of the effect to a combination of lattice-mismatch strain and O-sublattice incompatibility. Strain alone in bulk YSZ enhances O mobility at high temperatures by inducing extreme O disorder. In multilayer structures, O-sublattice incompatibility causes the same extreme disorder at room temperature.

  18. Study of interface correlation in W/C multilayer structure by specular and non-specular grazing incidence X-ray reflectivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, A., E-mail: arupb@barc.gov.in; Bhattacharyya, D.; Sahoo, N. K. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Maidul Haque, S.; Tripathi, S.; De, Rajnarayan [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, VIZAG Centre, Visakhapatnam 530012 (India); Rai, S. [Indus Synchrotron Utilization Division, Raja Raman Centre for Advanced Technology, Indore 452013 (India)

    2015-10-28

    W/C/W tri-layer thin film samples have been deposited on c-Si substrates in a home-built Ion Beam Sputtering system at 1.5 × 10{sup −3} Torr Ar working pressure and 10 mA grid current. The tri-layer samples have been deposited at different Ar{sup +} ion energies between 0.6 and 1.2 keV for W layer deposition and the samples have been characterized by specular and non-specular grazing incidence X-ray reflectivity (GIXR) measurements. By analyzing the GIXR spectra, various interface parameters have been obtained for both W-on-C and C-on-W interfaces and optimum Ar{sup +} ion energy for obtaining interfaces with low imperfections has been found. Subsequently, multilayer W/C samples with 5-layer, 7-layer, 9-layer, and 13-layer have been deposited at this optimum Ar{sup +} ion energy. By fitting the specular and diffused GIXR data of the multilayer samples with the parameters of each interface as fitting variables, different interface parameters, viz., interface width, in-plane correlation length, interface roughness, and interface diffusion have been estimated for each interface and their variation across the depth of the multilayers have been obtained. The information would be useful in realizing W/C multilayers for soft X-ray mirror application in the <100 Å wavelength regime. The applicability of the “restart of the growth at the interface” model in the case of these ion beam sputter deposited W/C multilayers has also been investigated in the course of this study.

  19. Capping layer-tailored interface magnetic anisotropy in ultrathin Co2FeAl films

    International Nuclear Information System (INIS)

    Belmeguenai, M.; Zighem, F.; Chérif, S. M.; Gabor, M. S.; Petrisor, T.; Tiusan, C.

    2015-01-01

    Co 2 FeAl (CFA) thin films of various thicknesses (2 nm ≤ d ≤ 50 nm) have been grown on (001) MgO single crystal substrates and then capped with Cr, V, and Ta. Their magnetic and structural properties have been studied by x-ray diffraction (XRD), vibrating sample magnetometry, and broadband microstrip ferromagnetic resonance (MS-FMR). The XRD revealed that the films are epitaxial with the cubic [001] CFA axis normal to the substrate plane and that the chemical order varies from the B2 phase to the A2 phase when decreasing the thickness. The deduced lattice parameters showed that the Cr-capped films exhibit a larger tetragonal distortion, as compared with the films capped with V or Ta. The presence of magnetic dead layers has been observed in CFA samples capped with V and Ta but not in the case of the Cr-capped ones. The effective magnetization, deduced from the fit of MS-FMR measurements, increases (decreases) linearly with the CFA inverse thickness (1/d) for the Cr-capped (Ta-capped) films while it is constant for the V-capped ones. This allows quantifying the perpendicular surface anisotropy coefficients of −0.46 erg/cm 2 and 0.74 erg/cm 2 for Cr and Ta-capped films, respectively. Moreover, the fourfold and the uniaxial anisotropy fields, measured in these films, showed different trends with a respect to the CFA inverse thickness. This allows inferring that a non-negligible part of the fourfold magnetocrystalline term is of interfacial origin

  20. Controlled lateral anisotropy in correlated manganite heterostructures by interface-engineered oxygen octahedral coupling

    NARCIS (Netherlands)

    Liao, Zhaoliang; Huijben, Mark; Zhong, Z.; Gauquelin, N.; Macke, S.; Green, R.J.; van Aert, S.; Verbeeck, J.; van Tendeloo, G.; Held, K.; Sawatzky, G.A.; Koster, Gertjan; Rijnders, Augustinus J.H.M.

    2016-01-01

    Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring the interface oxygen network could allow the development of correlated oxide-based magnetic tunnelling junctions with non-collinear magnetization, with possible practical applications as miniaturized

  1. Band alignment of ZnO/multilayer MoS{sub 2} interface determined by x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinke, E-mail: xkliu@szu.edu.cn, E-mail: liuwj@szu.edu.cn; He, Jiazhu; Chen, Le; Li, Kuilong; Jia, Fang; Zeng, Yuxiang; Lu, Youming; Zhu, Deliang; Liu, Wenjun, E-mail: xkliu@szu.edu.cn, E-mail: liuwj@szu.edu.cn [College of Materials Science and Engineering, Nanshan District Key Lab for Biopolymer and Safety Evaluation, Shenzhen University, 3688 Nanhai Ave, Shenzhen 518060 (China); Zhang, Yuan [School of Physics and Electronic Information, Hua Bei Normal University, 100 Dongshan Road, Huai Bei 235000 (China); Liu, Qiang; Yu, Wenjie [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Chang Ning Road, Shanghai 200050 (China); Wu, Jing [Institute of Materials research and Engineering (IMRE), 2 Fusionopolis Way, Innovis, #08-03, 138634 Singapore (Singapore); He, Zhubing [Department of Materials Science and Engineering, South University of Science and Technology of China, 1088 Xueyuan Road, Shenzhen 518055 (China); Ang, Kah-Wee [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore (Singapore)

    2016-08-15

    The energy band alignment between ZnO and multilayer (ML)-MoS{sub 2} was characterized using high-resolution x-ray photoelectron spectroscopy. The ZnO film was deposited using an atomic layer deposition tool, and ML-MoS{sub 2} was grown by chemical vapor deposition. A valence band offset (VBO) of 3.32 eV and a conduction band offset (CBO) of 1.12 eV were obtained for the ZnO/ML-MoS{sub 2} interface without any treatment. With CHF{sub 3} plasma treatment, a VBO and a CBO across the ZnO/ML-MoS{sub 2} interface were found to be 3.54 eV and 1.34 eV, respectively. With the CHF{sub 3} plasma treatment, the band alignment of the ZnO/ML-MoS{sub 2} interface has been changed from type II or staggered band alignment to type III or misaligned one, which favors the electron-hole pair separation. The band alignment difference is believed to be dominated by the down-shift in the core level of Zn 2p or the interface dipoles, which is caused by the interfacial layer rich in F.

  2. Photoelectric properties by interface effect of organic/inorganic(CuPc/PbTe) multilayer prepared by pulsed laser deposition and thermal evaporation

    CERN Document Server

    Lee, H Y; Choi, B C; Jeong, J H; Tabata, H; Kawai, T

    1999-01-01

    Highly crystallized CuPc/PbTe multilayer are prepared at substrate temperature from room temperature to 300 .deg. C by pulsed laser deposition and thermal evaporation method. From the measurement of AFM image, these all film exhibits composed of round grains and flat matrix. For observation the interface effect of multilayer, we measured the transverse current-voltage characteristics in the dark and under illumination. The photocarrier is generated in the CuPc layer and the electron-hole pairs are separated by the steep incline of the potential near the CuPc/PbTe interface. The CuPc/PbTe multilayers in the in-plane current-voltage curve exhibit larger photoconduction effect than that of CuPc single layer.

  3. Evolution of interface and surface structures of ZnO/Al2 O3 multilayers upon rapid thermal annealing

    Science.gov (United States)

    Liu, H. H.; Chen, Q. Y.; Chang, C. F.; Hsieh, W. C.; Wadekar, P. V.; Huang, H. C.; Liao, H. H.; Seo, H. W.; Chu, W. K.

    2015-03-01

    ZnO ∖Al2O3 multilayers were deposited on sapphires by atomic layer deposition at 85°C. This low substrate temperature ensures good interface smoothness useful for study of interfacial reaction or interdiffusion. Our study aimed at the effects of rapid thermal annealing at different annealing temperatures, times and PAr:PO2. XRR and XRD techniques were used to investigate the kinetics from which various terms of the activation energies could be determined. HR-TEM and electron diffraction were carried out to correlate the microstructures and interfacial alignments as a result of the reactions. AFM were used to assist SEM profiling of the surface morphological evolution in association with the TEM observations.

  4. Rheology at the Interface and the Role of the Interphase in Reactive Functionalized Multilayer Polymers in Coextrusion Process

    Science.gov (United States)

    Lamnawar, Khalid; Maazouz, Abderrahim

    2008-07-01

    Coextrusion technologies are commonly used to produce multilayered composite sheets or films for a large range of applications from food packaging to optics. The contrast of rheological properties between layers can lead to interfacial instabilities during flow. Important theoretical and experimental advances regarding the stability of compatible and incompatible polymers have, during the last decades, been made using a mechanical approach. However, few research efforts have been dedicated to the physicochemical affinity between the neighboring layers. The present study deals with the influence of this affinity on interfacial instabilities for functionalized incompatible polymers. Polyamide (PA6)/polyethylene grafted with glycidyl methacrylate (PE-GMA) was used as a reactive system and PE/PA6 as a non reactive one. Two grades of polyamide (PA6) were used in order to change the viscosity and elasticity ratios between PE (or PE-GMA) and PA6. It was experimentally confirmed, in this case, that weak disturbance can be predicted by considering an interphase of non-zero thickness (corresponding to an interdiffusion/reaction zone) instead of a purely geometrical interface between the two reactive layers. According to the rheological investigations from previous work which the interphase effect can be probed, an experimental strategy was here formulated to optimize the process by listing the parameters that controlled the stability of the reactive multilayer flows. Hence, based on this analysis, guidelines for a stable coextrusion of reactive functionalized polymers can be provided coupling the classical parameters (viscosity, elasticity and layer ratios) and the physicochemical affinity at the polymer/polymer interface.

  5. Origin of variation of shift field via annealing at 400°C in a perpendicular-anisotropy magnetic tunnel junction with [Co/Pt]-multilayers based synthetic ferrimagnetic reference layer

    Directory of Open Access Journals (Sweden)

    H. Honjo

    2017-05-01

    Full Text Available We investigated properties of perpendicular-anisotropy magnetic tunnel junctions (p-MTJs with [Co/Pt]-multilayer based synthetic ferrimagnetic reference (SyF layer at elevated annealing temperature Ta from 350°C to 400°C. Shift field HS defined as center field of minor resistance versus magnetic field curve of the MTJs increased with increase of Ta from 350°C to 400°C. The variation of HS is attributed to the variation of saturation magnetic moment in the SyF reference layer. Cross sectional energy dispersive X-ray spectroscopy analysis revealed that Fe element of CoFeB in the reference layer diffuses to Co/Pt multilayers in the SyF reference layer.

  6. The influence of polyanion molecular weight on polyelectrolyte multilayers at surfaces: elasticity and susceptibility to saloplasticity of strongly dissociated synthetic polymers at fluid-fluid interfaces.

    Science.gov (United States)

    Cramer, Ashley D; Dong, Wen-Fei; Benbow, Natalie L; Webber, Jessie L; Krasowska, Marta; Beattie, David A; Ferri, James K

    2017-09-13

    We studied the interfacial mechanical properties of polyelectrolyte multilayer assemblies of poly(diallylamine hydrochloride) (PAH) and poly(4-styrenesulfonate)sodium salt (PSS) at the air-water interface using axisymmetric drop shape analysis (ADSA) during hydrostatic inflation as a function of aqueous salt concentration and two different polyanion molecular weights (M w ∼ 13 and 70 kDa). Surface elastic moduli (G s ) ranged from 50 to 300 mN m -1 . Using the measured film thickness, the bulk moduli (G) ranged from 10 to 90 MPa consistent with elastomeric solids. This solid-like interface was evidenced by a systematic departure of the inflated shape from the Young-Laplace equation, which assumes a liquid-like interface. Surface elastic moduli increased and bulk elastic moduli decreased with increasing nanomembrane transverse dimension, and multilayers with the lower molecular weight anion were more transversely compact than those of higher molecular weight and displayed a larger elastic modulus. The bulk moduli of both types of multilayer assemblies asymptotically approach a constant value for films with more than two bilayers of polyelectrolyte, consistent with the observed transition from a 'glassy' to 'rubbery' state. Both types of multilayer assemblies displayed plasticization with increasing sodium chloride concentration in the adjoining aqueous phase, i.e. saloplasticity, and exhibited a transition from elastic to plastic response to deformation. The restored mobility of the polyelectrolyte resulting from the shift from intrinsic to extrinsic charge complexation, restores fluidity to the interface and is evidenced by experimental observation of a liquid-like interface when loaded. The higher molecular weight polyanion multilayers plasticized at lower salt concentrations suggesting that the lower melting point of the higher molecular weight polyanion assembly is attributable to a lesser extent of electrostatic cross-linking underscoring the unconventional

  7. Impact of multilayered compression bandages on sub-bandage interface pressure: a model.

    Science.gov (United States)

    Al Khaburi, J; Nelson, E A; Hutchinson, J; Dehghani-Sanij, A A

    2011-03-01

    Multi-component medical compression bandages are widely used to treat venous leg ulcers. The sub-bandage interface pressures induced by individual components of the multi-component compression bandage systems are not always simply additive. Current models to explain compression bandage performance do not take account of the increase in leg circumference when each bandage is applied, and this may account for the difference between predicted and actual pressures. To calculate the interface pressure when a multi-component compression bandage system is applied to a leg. Use thick wall cylinder theory to estimate the sub-bandage pressure over the leg when a multi-component compression bandage is applied to a leg. A mathematical model was developed based on thick cylinder theory to include bandage thickness in the calculation of the interface pressure in multi-component compression systems. In multi-component compression systems, the interface pressure corresponds to the sum of the pressures applied by individual bandage layers. However, the change in the limb diameter caused by additional bandage layers should be considered in the calculation. Adding the interface pressure produced by single components without considering the bandage thickness will result in an overestimate of the overall interface pressure produced by the multi-component compression systems. At the ankle (circumference 25 cm) this error can be 19.2% or even more in the case of four components bandaging systems. Bandage thickness should be considered when calculating the pressure applied using multi-component compression systems.

  8. Effect of interface intermixing on giant magnetoresistance in NiFe/Cu and Co/NiFe/Co/Cu multilayers

    International Nuclear Information System (INIS)

    Nagamine, L.C.C.M.; Biondo, A.; Pereira, L.G.; Mello, A.; Schmidt, J.E.; Chimendes, T.W.; Cunha, J.B.M.; Saitovitch, E.B.

    2003-01-01

    This article reports on the important influence of the spontaneously built-in paramagnetic interfacial layers on the magnetic and magnetoresistive properties of NiFe/Cu and Co/NiFe/Co/Cu multilayers grown by magnetron sputtering. A computational simulation, based on a semiclassical model, has been used to reproduce the variations of the resistivity and of the magnetoresistance (MR) amplitude with the thickness of the NiFe, Cu, and Co layers. We showed that the compositionally intermixed layers at NiFe/Cu interfaces, which are paramagnetic, reduce the flow of polarized electrons and produce a masking on the estimated mean-free path of both types of electrons due to the reduction of their effective values, mainly for small NiFe thickness. Moreover, the transmission coefficients for the electrons decrease when Fe buffer layers are replaced by NiFe ones. This result is interpreted in terms of the variations of the interfacial intermixing and roughness at the interfaces, leading to an increase of the paramagnetic interfacial layer thickness. The effect provoked by Co deposition at the NiFe 16 A/Cu interfaces has also been investigated. The maximum of the MR amplitudes was found at 5 A of Co, resulting in the quadruplication of the MR amplitude. This result is partially attributed to the interfacial spin-dependent scattering due to the increase of the magnetic order at interfaces. Another effect observed here was the increase of the spin-dependent scattering events in the bulk NiFe due to a larger effective NiFe thickness, since the paramagnetic interfacial layer thickness is decreased

  9. A Novel Multilayer Correlation Maximization Model for Improving CCA-Based Frequency Recognition in SSVEP Brain-Computer Interface.

    Science.gov (United States)

    Jiao, Yong; Zhang, Yu; Wang, Yu; Wang, Bei; Jin, Jing; Wang, Xingyu

    2018-05-01

    Multiset canonical correlation analysis (MsetCCA) has been successfully applied to optimize the reference signals by extracting common features from multiple sets of electroencephalogram (EEG) for steady-state visual evoked potential (SSVEP) recognition in brain-computer interface application. To avoid extracting the possible noise components as common features, this study proposes a sophisticated extension of MsetCCA, called multilayer correlation maximization (MCM) model for further improving SSVEP recognition accuracy. MCM combines advantages of both CCA and MsetCCA by carrying out three layers of correlation maximization processes. The first layer is to extract the stimulus frequency-related information in using CCA between EEG samples and sine-cosine reference signals. The second layer is to learn reference signals by extracting the common features with MsetCCA. The third layer is to re-optimize the reference signals set in using CCA with sine-cosine reference signals again. Experimental study is implemented to validate effectiveness of the proposed MCM model in comparison with the standard CCA and MsetCCA algorithms. Superior performance of MCM demonstrates its promising potential for the development of an improved SSVEP-based brain-computer interface.

  10. Effects of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers

    KAUST Repository

    Guo, Zaibing; Mi, W. B.; Aboljadayel, Razan; Zhang, Bei; Zhang, Q.; Gonzalez Barba, Priscila; Manchon, Aurelien; Zhang, Xixiang

    2012-01-01

    . By scaling surface scattering contribution with ρAHs∼ργss, the exponent γ has been found to decrease with the increase of surface scattering resistivity, which could account for the thickness-dependent anomalous Hall effect. Interface diffusion induced

  11. Dimensional behavior of the anisotropy in the mixed state of a-axis oriented EuBa{sub 2}Cu{sub 3}O{sub 7}/PrBa{sub 2}Cu{sub 3}O{sub 7} and EuBa{sub 2}Cu{sub 3}O{sub 7}/SrTiO{sub 3} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, E.M.; Gonzalez, J.M. [Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Ciencia de Materiales; Gomez, A.M. [Dept. de Fisica de Materiales, Univ. Nacional de Educacion a Distancia, Madrid (Spain); Vicent, J.L. [Dept. de Fisica de Materiales, Univ. Complutense, Madrid (Spain)

    1998-01-01

    Thin films and superconducting/insulating multilayers of the 123-high temperature superconductor (HTS) family have been grown by a sputtering technique. The samples are grown with the so-called a-axis orientation (CuO{sub 2} planes perpendicular to the substrate). The angular dependence of the onset of dissipation (resistivity) has been measured with applied magnetic fields up to 90 kOe. In the a-axis multilayers the artificially induced anisotropy oververcomes the intrinsic anisotropy in a broad angular interval, and the insulating layers break down the dimensional scaling laws above some critical angle ({theta}{sub c}). (orig.) 8 refs.

  12. Magnetic properties and interlayer coupling of sputtered Ni/V multilayers

    International Nuclear Information System (INIS)

    Benkirane, K.; Elkabil, R.; Lassri, M.; Abid, M.; Lassri, H.; Hamdoun, A.; Krishnan, R.

    2005-01-01

    The magnetic properties of sputtered Ni/V multilayers have been studied in a vibrating sample magnetometer, torque magnetometer and by ferromagnetic resonance (FMR). The magnetization decreases with decreasing Ni layer thickness, which is an indication of the structural imperfections at interface. The interface contribution to the magnetic anisotropy is practically negligible. The spin-waves resonance modes were observed for perpendicular geometry, which implied that spin waves were sustained by the whole film and propagated through V layers in some Ni/V multilayers. The relation of the resonance field H n with the mode number n obeys the so-called n 2 law and the interlayer exchange constants were determined

  13. Effect of antiferromagnetic interfacial coupling on spin-wave resonance frequency of multi-layer film

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Rong-ke, E-mail: rkqiu@163.com; Cai, Wei

    2017-08-15

    Highlights: • A quantum approach is developed to study the SWR of a bicomponent multi-layer films. • The comparison of the SWR in films with FM and AFM interfacial coupling has been made. • The present results show the method to enhance and adjust the SWR frequency of films. - Abstract: We investigate the spin-wave resonance (SWR) frequency in a bicomponent bilayer and triple-layer films with antiferromagnetic or ferromagnetic interfacial couplings, as function of interfacial coupling, surface anisotropy, interface anisotropy, thickness and external magnetic field, using the linear spin-wave approximation and Green’s function technique. The microwave properties for multi-layer magnetic film with antiferromagnetic interfacial coupling is different from those for multi-layer magnetic film with ferromagnetic interfacial coupling. For the bilayer film with antiferromagnetic interfacial couplings, as the lower (upper) surface anisotropy increases, only the SWR frequencies of the odd (even) number modes increase. The lower (upper) surface anisotropy does not affect the SWR frequencies of the even (odd) number modes{sub .} For the multi-layer film with antiferromagnetic interfacial coupling, the SWR frequency of modes m = 1, 3 and 4 decreases while that of mode m = 2 increases with increasing thickness of the film within a proper parameter region. The present results could be useful in enhancing our fundamental understanding and show the method to enhance and adjust the SWR frequency of bicomponent multi-layer magnetic films with antiferromagnetic or ferromagnetic interfacial coupling.

  14. Non-destructive spatial characterization of buried interfaces in multilayer stacks via two color picosecond acoustics

    Science.gov (United States)

    Faria, Jorge C. D.; Garnier, Philippe; Devos, Arnaud

    2017-12-01

    We demonstrate the ability to construct wide-area spatial mappings of buried interfaces in thin film stacks in a non-destructive manner using two color picosecond acoustics. Along with the extraction of layer thicknesses and sound velocities from acoustic signals, the morphological information presented is a powerful demonstration of phonon imaging as a metrological tool. For a series of heterogeneous (polymer, metal, and semiconductor) thin film stacks that have been treated with a chemical procedure known to alter layer properties, the spatial mappings reveal changes to interior thicknesses and chemically modified surface features without the need to remove uppermost layers. These results compare well to atomic force microscopy scans showing that the technique provides a significant advantage to current characterization methods for industrially important device stacks.

  15. Thermal variation of magnetization in Ni/V multilayers

    International Nuclear Information System (INIS)

    Benkirane, K.; Elkabil, R.; Hamdoun, A.; Lassri, M.; Abid, M.; Lassri, H.; Krishnan, R.

    2004-01-01

    The magnetic properties of Ni/V multilayers, prepared by the RF sputtering method, have been systematically studied by magnetic measurements. The magnetization decreases with a decrease in Ni layer thickness tNi and the analysis of the results at 5K indicates the presence of a dead Ni layer about 12A thick. The effective anisotropy Keff of Ni/V multilayers is obtained using a torque magnetometer. The interface contribution to the magnetic anisotropy is practically negligible. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction Jb, surface exchange interaction JS, and the interlayer coupling strength JI for various Ni layer thicknesses have been obtained

  16. Perpendicular magnetic anisotropy at the interface between ultrathin Fe film and MgO studied by angular-dependent x-ray magnetic circular dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Okabayashi, J. [Research Center for Spectrochemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Koo, J. W.; Mitani, S. [National Institute for Materials Science (NIMS), Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8577 (Japan); Sukegawa, H. [National Institute for Materials Science (NIMS), Tsukuba 305-0047 (Japan); Takagi, Y.; Yokoyama, T. [Institute of Molecular Science, Okazaki, Aichi 444-8585 (Japan)

    2014-09-22

    Interface perpendicular magnetic anisotropy (PMA) in ultrathin Fe/MgO (001) has been investigated using angular-dependent x-ray magnetic circular dichroism (XMCD). We found that anisotropic orbital magnetic moments deduced from the analysis of XMCD contribute to the large PMA energies, whose values depend on the annealing temperature. The large PMA energies determined from magnetization measurements are related to those estimated from the XMCD and the anisotropic orbital magnetic moments through the spin-orbit interaction. The enhancement of anisotropic orbital magnetic moments can be explained mainly by the hybridization between the Fe 3d{sub z}{sup 2} and O 2p{sub z} states.

  17. Probing buried solid-solid interfaces in magnetic multilayer structures and other nanostructures using spectroscopy excited by soft x-ray standing waves

    International Nuclear Information System (INIS)

    Yang, S.-H.; Mun, B.S.; Mannella, N.; Sell, B.; Ritchey, S.B.; Fadley, C.S.; Pham, L.; Nambu, A.; Watanabe, M.

    2004-01-01

    Full text: Buried solid-solid interfaces are becoming increasingly more important in all aspects of nanoscience, and we here dis- cuss the st applications of a new method for selectively studying them with the vuv/soft x-ray spectroscopies. As specific examples, magnetic multilayer structures represent key elements of current developments in spintronics, including giant magnetoresistance, exchange bias, and magnetic tunnel resistance. The buried interfaces in such structures are of key importance to their performance, but have up to now been difficult to study selectively with these spectroscopies. This novel method involves excitation of photoelectrons or fluorescent x-rays with soft x-ray standing waves created by Bragg reflection from a multilayer mirror substrate on which the sample is grown. We will discuss core and valence photoemission, as well soft x-ray emission, results from applying this method to multilayer structures relevant to both giant magnetoresistance (Fe/Cr-[2]) and magnetic tunnel junctions (Al 2 O 3 /FeCo) , including magnetic dichroism measurements. Work supported by the Director, Of e of Science, Of e of Basic Energy Sciences, Materials Science and Engineering Division, U.S. Department of Energy, Contract No. DE-AC03-76SF000

  18. Effect of heavy-metal insertions at Fe/MgO interfaces on electric-field-induced modification of magnetocrystalline anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, K.; Nomura, T. [Department of Physics Engineering, Mie University, Tsu, Mie 514-8507 (Japan); Pradipto, A.-M. [Department of Physics Engineering, Mie University, Tsu, Mie 514-8507 (Japan); Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Nawa, K.; Akiyama, T.; Ito, T. [Department of Physics Engineering, Mie University, Tsu, Mie 514-8507 (Japan)

    2017-05-01

    Magnetocrystalline anisotropy (MCA) at Fe/MgO interfaces with insertions of 3d (Co, Ni), 4d (Ru, Rh, Pd), and 5d (Os, Ir, Pt) elements in external electric fields was investigated from first-principles calculations. The MCA energy and the electric-field-induced MCA modification dramatically depend on the inserted elements. Large MCA modification may be achieved by heavy-metal insertions, in which the strength of spin-orbit coupling of inserted elements and the position of the Fermi level relative to d band level play key roles. - Highlights: • MCA at Fe/MgO interface dramatically depends on insertions of 3d, 4d, and 5d elements. • Large electric-field-induced MCA modification is achieved by heavy-metal insertions. • Position of Fermi level relative to d band level plays key role in determining MCA.

  19. First-principles investigation of the very large perpendicular magnetic anisotropy at Fe | MgO and Co | MgO interfaces

    KAUST Repository

    Yang, H. X.; Chshiev, M.; Dieny, B.; Lee, J. H.; Manchon, Aurelien; Shin, K. H.

    2011-01-01

    The perpendicular magnetic anisotropy (PMA) arising at the interface between ferromagnetic transition metals and metallic oxides was investigated via first-principles calculations. In this work very large values of PMA, up to 3 erg/cm2, at Fe|MgO interfaces are reported, in agreement with recent experiments. The origin of PMA is attributed to overlap between O-pz and transition metal dz2 orbitals hybridized with dxz(yz) orbitals with stronger spin-orbit coupling-induced splitting around the Fermi level for perpendicular magnetization orientation. Furthermore, it is shown that the PMA value weakens in the case of over- or underoxidation due to the fact that oxygen pz and transition metal dz2 orbital overlap is strongly affected by disorder, in agreement with experimental observations in magnetic tunnel junctions.

  20. First-principles investigation of the very large perpendicular magnetic anisotropy at Fe | MgO and Co | MgO interfaces

    KAUST Repository

    Yang, H. X.

    2011-08-01

    The perpendicular magnetic anisotropy (PMA) arising at the interface between ferromagnetic transition metals and metallic oxides was investigated via first-principles calculations. In this work very large values of PMA, up to 3 erg/cm2, at Fe|MgO interfaces are reported, in agreement with recent experiments. The origin of PMA is attributed to overlap between O-pz and transition metal dz2 orbitals hybridized with dxz(yz) orbitals with stronger spin-orbit coupling-induced splitting around the Fermi level for perpendicular magnetization orientation. Furthermore, it is shown that the PMA value weakens in the case of over- or underoxidation due to the fact that oxygen pz and transition metal dz2 orbital overlap is strongly affected by disorder, in agreement with experimental observations in magnetic tunnel junctions.

  1. FANTEN: a new web-based interface for the analysis of magnetic anisotropy-induced NMR data

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldelli, Mauro; Carlon, Azzurra; Ravera, Enrico; Parigi, Giacomo, E-mail: parigi@cerm.unifi.it; Luchinat, Claudio, E-mail: luchinat@cerm.unifi.it [University of Florence, CERM and Department of Chemistry “Ugo Schiff” (Italy)

    2015-01-15

    Pseudocontact shifts (PCSs) and residual dipolar couplings (RDCs) arising from the presence of paramagnetic metal ions in proteins as well as RDCs due to partial orientation induced by external orienting media are nowadays routinely measured as a part of the NMR characterization of biologically relevant systems. PCSs and RDCs are becoming more and more popular as restraints (1) to determine and/or refine protein structures in solution, (2) to monitor the extent of conformational heterogeneity in systems composed of rigid domains which can reorient with respect to one another, and (3) to obtain structural information in protein–protein complexes. The use of both PCSs and RDCs proceeds through the determination of the anisotropy tensors which are at the origin of these NMR observables. A new user-friendly web tool, called FANTEN (Finding ANisotropy TENsors), has been developed for the determination of the anisotropy tensors related to PCSs and RDCs and has been made freely available through the WeNMR ( http://fanten-enmr.cerm.unifi.it:8080 http://fanten-enmr.cerm.unifi.it:8080 ) gateway. The program has many new features not available in other existing programs, among which the possibility of a joint analysis of several sets of PCS and RDC data and the possibility to perform rigid body minimizations.

  2. Microscopic origin of the unidirectional anisotropy on the exchange-coupled CoO/Co interface; Mikroskopischer Ursprung der unidirektionalen Anisotropie an der austauschgekoppelten CoO/Co-Grenzflaeche

    Energy Technology Data Exchange (ETDEWEB)

    Ghadimi, M.R.

    2006-03-03

    Exchange coupling at the interface between an antiferromagnet (AFM) and a ferromagnet (FM) causes unidirectional anisotropy of the FM layer, which induces a shift of the hysteresis loop along the magnetic field axis. In order to understand the microscopic origin of EB, the domain state (DS) model was proposed. This model is based on the physics of diluted antiferromagnets in an external magnetic field (DAFF) and yields the description of the most salient EB features of any model to date. The intentional dilution is realized by implementing non-magnetic defects in the bulk of the AFM. Under certain conditions, DAFF develops in a metastable domain state after cooling below the Neel-temperature in an external magnetic field. These domains carry a remanent domain state magnetization. One part of the domain state magnetization, the so-called irreversible domain state magnetization, provides the exchange coupling field at the interface to the FM layer giving rise to the EB. The stability and the size of the domains in the AFM and therefore the EB can be controlled by the number of defects and their different types throughout the volume part of the AFM. In this work, the experimental evidences of a direct influence of different types of defects (twins and 3d-growth as structural defects and dilution as substitutional defects) on the EB in epitaxially grown CoO/Co bilayers are presented. Furthermore, the influence of the crystal orientation of the CoO layer on EB is demonstrated. (orig.)

  3. Dynamic study of a sliding interface wear process of TiAlN and CrN multi-layers by X-ray absorption

    DEFF Research Database (Denmark)

    Rasmussen, Inge Lise; Guibert, M.; Belin, M.

    reactions at the interface. The basic physical and chemical processes on the nano-scale are, however, not yet known fully. Thus, the work presented here is a contribution to the knowledge of the area. The main objectives of this dynamical investigation are to show that real time and in-situ tribology...... in France. The contact under investigation (TiAlN/CrN/TiAlN (2000nm/1000nm/2000nm) multi-layer system) was exposed to a reciprocating sliding motion under a normal load. Simultaneously, the contact zone was submitted to a direct, focused and monochromatic SR photon beam. In this way we have studied...

  4. Interfacial effects in multilayers

    International Nuclear Information System (INIS)

    Barbee, T.W. Jr.

    1998-01-01

    Interfacial structure and the atomic interactions between atoms at interfaces in multilayers or nano-laminates have significant impact on the physical properties of these materials. A technique for the experimental evaluation of interfacial structure and interfacial structure effects is presented and compared to experiment. In this paper the impact of interfacial structure on the performance of x-ray, soft x-ray and extreme ultra-violet multilayer optic structures is emphasized. The paper is concluded with summary of these results and an assessment of their implications relative to multilayer development and the study of buried interfaces in solids in general

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

    Directory of Open Access Journals (Sweden)

    Takeshi Tainosho

    2017-05-01

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

  6. Interface behavior of a multi-layer fluid configuration subject to acceleration in a microgravity environment, supplement 1. M.S. Thesis

    Science.gov (United States)

    Lyell, M. J.; Roh, Michael

    1991-01-01

    With the increasing opportunities for research in a microgravity environment, there arises a need for understanding fluid mechanics under such conditions. In particular, a number of material processing configurations involve fluid-fluid interfaces which may experience instabilities in the presence of external forcing. In a microgravity environment, these accelerations may be periodic or impulse-type in nature. This research investigates the behavior of a multi-layer idealized fluid configuration which is infinite in extent. The analysis is linear, and each fluid region is considered inviscid, incompressible, and immiscible. An initial parametric study of confiquration stability in the presence of a constant acceleration field is performed. The zero mean gravity limit case serves as the base state for the subsequent time-dependent forcing cases. A stability analysis of the multi-layer fluid system in the presence of periodic forcing is investigated. Floquet theory is utilized. A parameter study is performed, and regions of stability are identified. For the impulse-type forcing case, asymptotic stability is established for the configuration. Using numerical integration, the time response of the interfaces is determined.

  7. Interface-driven alloying and metallic glass formation in nano-multilayers in an immiscible Y-Nb system

    International Nuclear Information System (INIS)

    Chen, Y.G.; Liu, B.X.; Nanjing Univ.

    1999-01-01

    Several new amorphous alloys were obtained in an immiscible Y-Nb system by room temperature 190 keV xenon ion mixing of Y-Nb multilayered films, which were designed to include a sufficient fraction of interfacial atoms and thus possessed a high free energy comparable to that of the amorphous state. In addition, two metastable f.c.c. phases were formed in Y-rich and Nb-rich multilayered films, respectively. The growth kinetics of the f.c.c. phases and their effect on the composition range of amorphization are also discussed. To understand the observed unusual alloying behaviors, a Gibbs free-energy diagram was constructed based on Miedema's model. The diagram included the free-energy curves of all the involved phases as well as that of the Y-Nb multilayered films including the extra interfacial free energy and thus gave a qualitative and reasonable interpretation to the formation of metastable alloys upon ion mixing. Furthermore, some multilayered films with a sufficient fraction of interfacial atoms were subjected to steady-state thermal annealing, which also resulted in the formation of the Y-Nb amorphous phases, suggesting that alloying in this immiscible system was actually driven by the interfacial free energy

  8. Effects of layer interface slip on the response and performance of elastic multi-layered flexible airport pavement systems

    CSIR Research Space (South Africa)

    Maina, JW

    2007-08-01

    Full Text Available in this study. The new AASHTO pavement design guide for flexible pavements is shifting from an experience (or purely empirical) based design method to a mechanistic-empirical (M-E) design method. The latter approach requires an elastic multi-layered analysis...

  9. Capping layer-tailored interface magnetic anisotropy in ultrathin Co{sub 2}FeAl films

    Energy Technology Data Exchange (ETDEWEB)

    Belmeguenai, M., E-mail: belmeguenai.mohamed@univ-paris13.fr; Zighem, F.; Chérif, S. M. [LSPM (CNRS-UPR 3407), Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, 93430 Villetaneuse (France); Gabor, M. S., E-mail: mihai.gabor@phys.utcluj.ro; Petrisor, T. [Center for Superconductivity, Spintronics and Surface Science, Department of Physics and Chemistry, Technical University of Cluj-Napoca, Str. Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Tiusan, C. [Center for Superconductivity, Spintronics and Surface Science, Department of Physics and Chemistry, Technical University of Cluj-Napoca, Str. Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Lorraine Université, BP 70239, F-54506 Vandoeuvre (France)

    2015-01-14

    Co{sub 2}FeAl (CFA) thin films of various thicknesses (2 nm ≤ d ≤ 50 nm) have been grown on (001) MgO single crystal substrates and then capped with Cr, V, and Ta. Their magnetic and structural properties have been studied by x-ray diffraction (XRD), vibrating sample magnetometry, and broadband microstrip ferromagnetic resonance (MS-FMR). The XRD revealed that the films are epitaxial with the cubic [001] CFA axis normal to the substrate plane and that the chemical order varies from the B2 phase to the A2 phase when decreasing the thickness. The deduced lattice parameters showed that the Cr-capped films exhibit a larger tetragonal distortion, as compared with the films capped with V or Ta. The presence of magnetic dead layers has been observed in CFA samples capped with V and Ta but not in the case of the Cr-capped ones. The effective magnetization, deduced from the fit of MS-FMR measurements, increases (decreases) linearly with the CFA inverse thickness (1/d) for the Cr-capped (Ta-capped) films while it is constant for the V-capped ones. This allows quantifying the perpendicular surface anisotropy coefficients of −0.46 erg/cm{sup 2} and 0.74 erg/cm{sup 2} for Cr and Ta-capped films, respectively. Moreover, the fourfold and the uniaxial anisotropy fields, measured in these films, showed different trends with a respect to the CFA inverse thickness. This allows inferring that a non-negligible part of the fourfold magnetocrystalline term is of interfacial origin.

  10. Spin-Orbit Torques in Co/Pd Multilayer Nanowires

    KAUST Repository

    Jamali, Mahdi; Narayanapillai, Kulothungasagaran; Qiu, Xuepeng; Loong, Li Ming; Manchon, Aurelien; Yang, Hyunsoo

    2013-01-01

    Current induced spin-orbit torques have been studied in ferromagnetic nanowires made of 20 nm thick Co/Pd multilayers with perpendicular magnetic anisotropy. Using Hall voltage and lock-in measurements, it is found that upon injection of an electric current both in-plane (Slonczewski-like) and perpendicular (fieldlike) torques build up in the nanowire. The torque efficiencies are found to be as large as 1.17 and 5 kOe at 108  A/cm2 for the in-plane and perpendicular components, respectively, which is surprisingly comparable to previous studies in ultrathin (∼1  nm) magnetic bilayers. We show that this result cannot be explained solely by spin Hall effect induced torque at the outer interfaces, indicating a probable contribution of the bulk of the Co/Pd multilayer.

  11. Spin-Orbit Torques in Co/Pd Multilayer Nanowires

    KAUST Repository

    Jamali, Mahdi

    2013-12-09

    Current induced spin-orbit torques have been studied in ferromagnetic nanowires made of 20 nm thick Co/Pd multilayers with perpendicular magnetic anisotropy. Using Hall voltage and lock-in measurements, it is found that upon injection of an electric current both in-plane (Slonczewski-like) and perpendicular (fieldlike) torques build up in the nanowire. The torque efficiencies are found to be as large as 1.17 and 5 kOe at 108  A/cm2 for the in-plane and perpendicular components, respectively, which is surprisingly comparable to previous studies in ultrathin (∼1  nm) magnetic bilayers. We show that this result cannot be explained solely by spin Hall effect induced torque at the outer interfaces, indicating a probable contribution of the bulk of the Co/Pd multilayer.

  12. Analysis of buried interfaces in multilayer device structures with hard XPS (HAXPES) using a CrKα source

    DEFF Research Database (Denmark)

    Renault, O.; Martinez, E.; Zborowski, C.

    2018-01-01

    Applications of laboratory hard X-ray photoelectron spectroscopy on buried interfaces in devices are presented. We use a novel spectrometer fitted with a monochromated CrKα source (photon energy: 5414.9 eV) and a high-voltage analyzer. Elements buried at depths as deep as 25 nm underneath various...

  13. Wedged multilayer Laue lens

    International Nuclear Information System (INIS)

    Conley, Ray; Liu Chian; Qian Jun; Kewish, Cameron M.; Macrander, Albert T.; Yan Hanfei; Maser, Joerg; Kang, Hyon Chol; Stephenson, G. Brian

    2008-01-01

    A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures

  14. Experimental study of multilayer solid epitaxy: two-dimensional critical behavior of a quantum solid/superfluid interface

    International Nuclear Information System (INIS)

    Ramesh, S.

    1985-01-01

    This thesis constitutes the first precise, quantitative experimental study of layering transitions, two-dimensional critical temperatures, and their relation to surface roughening. The experiments used superfluid fourth sound to probe the liquid solid 4 He interface, by coupling with surface waves unique to this interface. An annular resonator with electric transducers was used to measure the fourth sound velocity c 4 in an exfoliated graphite (Grafoil) superleak. Measurements of the pressure dependence of the fourth sound resonance frequencies (and attenuation) from ∼6 bar to ∼26 bar were made along eight isotherms from 1.0 K to 1.7 K. Plots of fourth sound resonance frequency versus coverage clearly indicate layer-by-layer solid nucleation and epitaxal growth of hcp solid 4 He on the basal plane of graphite. Further analysis yielded solid adsorption isotherms and a kinetic growth coefficient for the 4 He crystal surface and also indicated the existence of a critical temperature region and also indicated the existence of a critical temperature region around 1.0-1.2 K (the region of a bulk roughening transition). The acoustical theory for the experimental system was worked out using a parallel waveguide model; Landau's thermohydrodynamic equations were reformulated by including the mass- and heat-exchange effects occurring in the system; the equations were solved to obtain expressions for the velocity of sound propagation and attenuation

  15. Magnetic metallic multilayers

    International Nuclear Information System (INIS)

    Hood, R.Q.

    1994-04-01

    Utilizing self-consistent Hartree-Fock calculations, several aspects of multilayers and interfaces are explored: enhancement and reduction of the local magnetic moments, magnetic coupling at the interfaces, magnetic arrangements within each film and among non-neighboring films, global symmetry of the systems, frustration, orientation of the various moments with respect to an outside applied field, and magnetic-field induced transitions. Magnetoresistance of ferromagnetic-normal-metal multilayers is found by solving the Boltzmann equation. Results explain the giant negative magnetoresistance encountered in these systems when an initial antiparallel arrangement is changed into a parallel configuration by an external magnetic field. The calculation depends on (1) geometric parameters (thicknesses of layers), (2) intrinsic metal parameters (number of conduction electrons, magnetization, and effective masses in layers), (3) bulk sample properties (conductivity relaxation times), (4) interface scattering properties (diffuse scattering versus potential scattering at the interfaces, and (5) outer surface scattering properties (specular versus diffuse surface scattering). It is found that a large negative magnetoresistance requires considerable asymmetry in interface scattering for the two spin orientations. Features of the interfaces that may produce an asymmetrical spin-dependent scattering are studied: varying interfacial geometric random roughness with no lateral coherence, correlated (quasi-periodic) roughness, and varying chemical composition of the interfaces. The interplay between these aspects of the interfaces may enhance or suppress the magnetoresistance, depending on whether it increases or decreases the asymmetry in the spin-dependent scattering of the conduction electrons

  16. Utilizing ultrathin DNA/poly-lysine multilayer films to create liquid/liquid interfaces: spectroscopic characterization, interfacial reactions and nanoparticle adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hye Jin; Wark, Alastair W; Corn, Robert M [Department of Chemistry, University of California-Irvine, Irvine, CA 92697 (United States)

    2007-09-19

    Alternating electrostatic multilayer adsorption of poly-L-lysine (pLys) and DNA is used to create well-defined biopolymer multilayers for use as an ultrathin aqueous phase in liquid-liquid interfacial measurements. The molecular structure and thickness of the polyelectrolyte multilayers are determined using a combination of polarization modulation FT-IR reflection-absorption spectroscopy (PM-FTIRRAS) and FT-surface plasmon resonance (FT-SPR) thickness measurements. Electroactive species such as ferri/ferrocyanide ions can be incorporated into the DNA/pLys polyelectrolyte multilayers. The ion transport activity of these electroactive films when in contact with 1,2-dichoroethane is verified by electrochemical measurements. Micron-sized patterns of these multilayers are created by either photopatterning, vapour-deposited spot patterning or microfluidic stencil processing, and are used in conjunction with fluorescence and surface plasmon resonance imaging (SPRI) to monitor (i) the intercalation of dye molecules into DNA/pLys ultrathin films, (ii) the electrostatic adsorption of gold nanoparticles onto DNA/pLys multilayers and (iii) the spatially controlled incorporation and reaction of enzymes into patterned biopolymer multilayers.

  17. Anisotropic in-plane thermal conductivity in multilayer silicene

    Science.gov (United States)

    Zhou, Yang; Guo, Zhi-Xin; Chen, Shi-You; Xiang, Hong-Jun; Gong, Xin-Gao

    2018-06-01

    We systematically study thermal conductivity of multilayer silicene by means of Boltzmann Transportation Equation (BTE) method. We find that their thermal conductivity strongly depends on the surface structures. Thermal conductivity of bilayer silicene varies from 3.31 W/mK to 57.9 W/mK with different surface structures. Also, the 2 × 1 surface reconstruction induces unusual large thermal conductivity anisotropy, which reaches 70% in a four-layer silicene. We also find that the anisotropy decreases with silicene thickness increasing, owing to the significant reduction of thermal conductivity in the zigzag direction and its slight increment in the armchair direction. Finally, we find that both the phonon-lifetime anisotropy and the phonon-group-velocity anisotropy contribute to the thermal conductivity anisotropy of multilayer silicene. These findings could be helpful in the field of heat management, thermoelectric applications involving silicene and other multilayer nanomaterials with surface reconstructions in the future.

  18. Anomalous Hall effect and magnetoresistance behavior in Co/Pd1−xAgx multilayers

    KAUST Repository

    Guo, Z. B.

    2013-02-13

    In this paper, we report anomalous Hall effect (AHE) correlated with the magnetoresistance behavior in [Co/Pd1-xAg x]n multilayers. For the multilayers with n = 6, the increase in Ag content from x = 0 to 0.52 induces the change in AHE sign from negative surface scattering-dominated AHE to positive interface scattering-dominated AHE, which is accompanied with the transition from anisotropy magnetoresistance (AMR) dominated transport to giant magnetoresistance (GMR) dominated transport. For n = 80, scaling analysis with Rs ∝ρ xx γ yields γ ∼ 3.44 for x = 0.52 which presents GMR-type transport, in contrast to γ ∼ 5.7 for x = 0 which presents AMR-type transport. © 2013 American Institute of Physics.

  19. Structure and magnetic properties of Co/Pd multilayers prepared on porous nanotubular TiO{sub 2} substrate

    Energy Technology Data Exchange (ETDEWEB)

    Maximenko, A. [Institute of Nuclear Physics Polish Academy of Sciences, PL 31-342 Krakow (Poland); Research Institute for Nuclear Problems of Belarusian State University, Bobruiskaya str. 11, 220030 Minsk (Belarus); Marszałek, M., E-mail: marta.marszalek@ifj.edu.pl [Institute of Nuclear Physics Polish Academy of Sciences, PL 31-342 Krakow (Poland); Fedotova, J. [Research Institute for Nuclear Problems of Belarusian State University, Bobruiskaya str. 11, 220030 Minsk (Belarus); Zarzycki, A.; Zabila, Y. [Institute of Nuclear Physics Polish Academy of Sciences, PL 31-342 Krakow (Poland); Kupreeva, O.; Lazarouk, S. [Belarusian State University of Informatics and Radioelectronics, P.Brovka str. 6, 220013 Minsk (Belarus); Kasiuk, J. [Research Institute for Nuclear Problems of Belarusian State University, Bobruiskaya str. 11, 220030 Minsk (Belarus); Zavadski, S. [Belarusian State University of Informatics and Radioelectronics, P.Brovka str. 6, 220013 Minsk (Belarus)

    2017-07-15

    Highlights: • nanotubular templates of TiO{sub 2} were applied for fabrication of Co/Pd antidot arrays. • morphology of porous multilayers followed the features of the initial template. • the formation of Co0.4Pd0.6 alloy at the Co/Pd interface. • the conservation of perpendicular magnetic anisotropy in the CoPd porous film. • change of the magnetization reversal from domain wall motion to coherent rotation. - Abstract: We used porous nanotubular templates of TiO{sub 2} for fabrication of Co/Pd antidot arrays with strong perpendicular magnetic anisotropy. The morphology of porous multilayers followed the features of the initial template demonstrating a pronounced relief consisting of the cells with periodic pores with small inclination. We confirmed the formation of Co{sub 0.4}Pd{sub 0.6} alloy at the Co/Pd interface. We observed the conservation of perpendicular magnetic anisotropy in the Co/Pd porous film with coercive field H{sub C} = 2.7 kOe, enhanced with respect to the continuous film due to the pinning of magnetic moments on the nanopore edges. From angular dependence of the coercive field H{sub C} we deduced the change of the magnetization reversal mechanism from domain wall motion in the continuous film to the predominantly coherent rotation mechanism in the porous film.

  20. Magnetic properties of Co/Pt-Pd multilayer thin film media

    Energy Technology Data Exchange (ETDEWEB)

    Inaba, N.; Igarashi, S.; Fujita, F.; Koike, K.; Kato, H. [Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Kirino, F. [National University of Fine Arts and Music, Taitou-ku, Tokyo 110-8714 (Japan)

    2007-12-15

    We investigated the dependence of magnetic properties for Co/Pt{sub 100-x}Pd{sub x} multilayer thin films on the concentration in the Pt-Pd alloy layers. Perpendicular magneto anisotropy constant K {sub p} increases with increasing Pt concentration in the Pt-Pd layer, since the interface anisotropy between the Co and the Pt-Pd layers is enhanced by the increase of the Pt concentration. The Curie temperature and the temperature dependence of K{sub p} for the specimens increase with increasing the amount of Pt in the Pt-Pd layer. These results may indicate that the lattice distortion of the Co layer caused by the interface from the Pt-Pd layer becomes larger and the increase of the distortion enhances the interface anisotropy, since the lattice misfit between the Pt-Pd and the Co increases with increasing the Pt concentration. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Solution pH and oligoamine molecular weight dependence of the transition from monolayer to multilayer adsorption at the air-water interface from sodium dodecyl sulfate/oligoamine mixtures.

    Science.gov (United States)

    Halacheva, S S; Penfold, J; Thomas, R K; Webster, J R P

    2013-05-14

    Neutron reflectivity and surface tension have been used to investigate the solution pH and oligoamine molecular weight dependence of the adsorption of sodium dodecyl sulfate (SDS)/oligoamine mixtures at the air-water interface. For diethylenetriamine, triamine, or triethylenetetramine, tetramine mixed with SDS, there is monolayer adsorption at pH 7 and 10, and multilayer adsorption at pH 3. For the slightly higher molecular weight tetraethylenepentamine, pentamine, and pentaethylenehexamine, hexamine, the adsorption is in the form of a monolayer at pH 3 and multilayers at pH 7 and 10. Hence, there is a pH driven transition from monolayer to multilayer adsorption, which shifts from low pH to higher pH as the oligoamine molecular weight increases from tetramine to pentamine. This results from the relative balance between the electrostatic attraction between the SDS and amine nitrogen group which decreases as the charge density decreases with increasing pH, the ion-dipole interaction between the amine nitrogen and SDS sulfate group which is dominant at higher pH, and the hydrophobic interalkyl chain interaction between bound SDS molecules which changes with oligoamine molecular weight.

  2. Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

    International Nuclear Information System (INIS)

    Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng; Wu, Zheng-Long; Feng, Chun; Li, Ming-Hua; Yu, Guang-Hua

    2016-01-01

    Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO_x (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K_C_o_F_e_B_/_M_g_O). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained

  3. Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Wu, Zheng-Long [Analytical and Testing Center, Beijing Normal University, Beijing 100875 (China); Feng, Chun, E-mail: fengchun@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Li, Ming-Hua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (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)

    2016-03-01

    Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO{sub x} (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K{sub CoFeB/MgO}). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained.

  4. Influence of layer thickness on the structure and the magnetic properties of Co/Pd epitaxial multilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Tobari, Kousuke, E-mail: tobari@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo 112-8551 (Japan); Ohtake, Mitsuru; Nagano, Katsumasa; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo 112-8551 (Japan)

    2012-03-15

    Co/Pd epitaxial multilayer films were prepared on Pd(111){sub fcc} underlayers hetero-epitaxially grown on MgO(111){sub B1} single-crystal substrates at room temperature by ultra-high vacuum RF magnetron sputtering. In-situ reflection high energy electron diffraction shows that the in-plane lattice spacing of Co on Pd layer gradually decreases with increasing the Co layer thickness, whereas that of Pd on Co layer remains unchanged during the Pd layer formation. The CoPd alloy phase formation is observed around the Co/Pd interface. The atomic mixing is enhanced for thinner Co and Pd layers in multilayer structure. With decreasing the Co and the Pd layer thicknesses and increasing the repetition number of Co/Pd multilayer film, stronger perpendicular magnetic anisotropy is observed. The relationships between the film structure and the magnetic properties are discussed. - Highlights: Black-Right-Pointing-Pointer Epitaxial Co/Pd multilayer films are prepared on Pd(111){sub fcc} underlayers. Black-Right-Pointing-Pointer Lattice strain in Co layer and CoPd-alloy formation are noted around the interface. Black-Right-Pointing-Pointer Magnetic property dependence on layer thickness is reported.

  5. A multi-physics modelling framework to describe the behaviour of nano-scale multilayer systems undergoing irradiation damage

    International Nuclear Information System (INIS)

    Villani, Aurelien

    2015-01-01

    using the finite elements method. Simulations of biaxial creep of polycrystalline aggregates coupled with vacancy diffusion are performed for the first time, and predict strongly heterogeneous viscoplastic strain fields. The classical macroscopic strain rate dependence on the stress and grain size is also retrieved. Void denuded zones close to the multilayer interfaces are obtained in irradiation simulations of a multilayer, in agreement with experimental observations. Finally, tensile tests of Cu-Nb multilayers are simulated in 3D, where it is shown that the effect of elastic anisotropy is negligible, and evidencing a complex deformation mode. (author)

  6. Band alignment of HfO{sub 2}/multilayer MoS{sub 2} interface determined by x-ray photoelectron spectroscopy: Effect of CHF{sub 3} treatment

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinke; He, Jiazhu; Tang, Dan; Jia, Fang; Lu, Youming, E-mail: ymlu@szu.edu.cn; Zhu, Deliang; Liu, Wenjun; Cao, Peijiang; Han, Sun [College of Materials Science and Engineering, Shenzhen Engineering Laboratory for Advanced Technology of Ceramics, Nanshan District Key Lab for Biopolymer and Safety Evaluation, Shenzhen University, 3688 Nanhai Ave, Shenzhen 518060 (China); Liu, Qiang; Wen, Jiao; Yu, Wenjie, E-mail: casan@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS,865 Chang Ning Road, Shanghai 200050 (China); Pan, Jisheng [Institute of Materials Research and Engineering, Agency for Science Technology and Research, Singapore 117602 (Singapore); He, Zhubing [Department of Materials Science and Engineering, South University of Science and Technology of China, 1088 Xueyuan Road, Shenzhen 518055 (China); Ang, Kah-Wee [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583 (Singapore)

    2015-09-07

    The energy band alignment between HfO{sub 2}/multilayer (ML)-MoS{sub 2} was characterized using high-resolution x-ray photoelectron spectroscopy. The HfO{sub 2} was deposited using an atomic layer deposition tool, and ML-MoS{sub 2} was grown by chemical vapor deposition. A valence band offset (VBO) of 1.98 eV and a conduction band offset (CBO) of 2.72 eV were obtained for the HfO{sub 2}/ML-MoS{sub 2} interface without any treatment. With CHF{sub 3} plasma treatment, a VBO and a CBO across the HfO{sub 2}/ML-MoS{sub 2} interface were found to be 2.47 eV and 2.23 eV, respectively. The band alignment difference is believed to be dominated by the down-shift in the core level of Hf 4d and up-shift in the core level of Mo 3d, or the interface dipoles, which caused by the interfacial layer in rich of F.

  7. Anomalous magnetoresistance in Fibonacci multilayers.

    Energy Technology Data Exchange (ETDEWEB)

    Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A. (Materials Science Division); (Universidade Federal do Rio Grande do Norte)

    2012-01-01

    We theoretically investigated magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely, [110] and [100]. We considered identical ferromagnetic layers separated by nonmagnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear coupling, and biquadratic coupling. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case, there is a different behavior for structures based on even and odd Fibonacci generations, and, more interesting, (ii) for the [100] case, we found magnetic field ranges for which the magnetoresistance increases with magnetic field.

  8. Porous germanium multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Garralaga Rojas, Enrique; Hensen, Jan; Brendel, Rolf [Institut fuer Solarenergieforschung Hameln (ISFH), Emmerthal (Germany); Carstensen, Juergen; Foell, Helmut [Chair for General Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany)

    2011-06-15

    We present the reproducible fabrication of porous germanium (PGe) single- and multilayers. Mesoporous layers form on heavily doped 4'' p-type Ge wafers by electrochemical etching in highly concentrated HF-based electrolytes with concentrations in a range of 30-50 wt.%. Direct PGe formation is accompanied by a constant dissolution of the already-formed porous layer at the electrolyte/PGe interface, hence yielding a thinner substrate after etching. This effect inhibits multilayer formation as the starting layer is etched while forming the second layer. We avoid dissolution of the porous layer by alternating the etching bias from anodic to cathodic. PGe formation occurs during anodic etching whereas the cathodic step passivates pore walls with H-atoms and avoids electropolishing. The passivation lasts a limited time depending on the etching current density and electrolyte concentration, necessitating a repetition of the cathodic step at suitable intervals. With optimized alternating bias mesoporous multilayer production is possible. We control the porosity of each single layer by varying the etching current density and the electrolyte (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Transfer matrices for multilayer structures

    International Nuclear Information System (INIS)

    Baquero, R.

    1988-08-01

    We consider four of the transfer matrices defined to deal with multilayer structures. We deduce algorithms to calculate them numerically, in a simple and neat way. We illustrate their application to semi-infinite systems using SGFM formulae. These algorithms are of fast convergence and allow a calculation of bulk-, surface- and inner-layers band structure in good agreement with much more sophisticated calculations. Supermatrices, interfaces and multilayer structures can be calculated in this way with a small computational effort. (author). 10 refs

  10. Amorphous FeCoSiB for exchange bias coupled and decoupled magnetoelectric multilayer systems: Real-structure and magnetic properties

    International Nuclear Information System (INIS)

    Hrkac, V.; Strobel, J.; Kienle, L.; Lage, E.; Köppel, G.; McCord, J.; Quandt, E.; Meyners, D.

    2014-01-01

    The effect of field annealing for exchanged biased multilayer films is studied with respect to the resultant structural and magnetic film properties. The presented multilayer stacks comprise repeating sequences of Ta/Cu/(1 1 1) textured antiferromagnetic Mn 70 Ir 30 /amorphous ferromagnetic Fe 70.2 Co 7.8 Si 12 B 10 . Within the ferromagnetic layers crystalline filaments are observed. An additional Ta layer between the antiferromagnet and ferromagnet is used in order to investigate and separate the influence of the common Mn 70 Ir 30 /Fe 70.2 Co 7.8 Si 12 B 10 interface on the occurring filaments and structural changes. In situ and ex situ transmission electron microscopy is used for a comprehensive structure characterization of multilayer stacks for selected temperature stages. Up to 250 °C, the multilayers are structurally unaltered and preserve the as-deposited condition. A deliberate increase to 350 °C exhibits different crystallization processes for the films, depending on the presence of crystal nuclei within the amorphous ferromagnetic layer. The influence of volume-to-surface ratio of the multilayer stacks to the crystallization process is emphasized by the comparison of in situ and ex situ investigations as the respective specimen thickness is changed. Complementary magnetic studies reveal a defined exchange bias obtained at the first annealing step and a decrease of total anisotropy field with partial crystallization after the subsequent annealing at 350 °C.

  11. Mechanical properties of highly textured Cu/Ni multilayers

    International Nuclear Information System (INIS)

    Liu, Y.; Bufford, D.; Wang, H.; Sun, C.; Zhang, X.

    2011-01-01

    We report on the synthesis of highly (1 1 1) and (1 0 0) textured Cu/Ni multilayers with individual layer thicknesses, h, varying from 1 to 200 nm. When, h, decreases to 5 nm or less, X-ray diffraction spectra show epitaxial growth of Cu/Ni multilayers. High resolution transmission electron microscopy studies show the coexistence of nanotwins and coherent layer interfaces in highly (1 1 1) textured Cu/Ni multilayers with smaller h. Hardnesses of multilayer films increase with decreasing h, approach a maximum at h of a few nanometers, and show softening thereafter at smaller h. The influence of layer interfaces as well as twin interfaces on strengthening mechanisms of multilayers and the formation of twins in Ni in multilayers are discussed.

  12. Elastic anisotropy of crystals

    Directory of Open Access Journals (Sweden)

    Christopher M. Kube

    2016-09-01

    Full Text Available An anisotropy index seeks to quantify how directionally dependent the properties of a system are. In this article, the focus is on quantifying the elastic anisotropy of crystalline materials. Previous elastic anisotropy indices are reviewed and their shortcomings discussed. A new scalar log-Euclidean anisotropy measure AL is proposed, which overcomes these deficiencies. It is based on a distance measure in a log-Euclidean space applied to fourth-rank elastic tensors. AL is an absolute measure of anisotropy where the limiting case of perfect isotropy yields zero. It is a universal measure of anisotropy applicable to all crystalline materials. Specific examples of strong anisotropy are highlighted. A supplementary material provides an anisotropy table giving the values of AL for 2,176 crystallite compounds.

  13. Magnetic multilayer structure

    Science.gov (United States)

    Herget, Philipp; O'Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2016-07-05

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  14. Tunable anomalous hall effect induced by interfacial catalyst in perpendicular multilayers

    Science.gov (United States)

    Zhang, J. Y.; Peng, W. L.; Sun, Q. Y.; Liu, Y. W.; Dong, B. W.; Zheng, X. Q.; Yu, G. H.; Wang, C.; Zhao, Y. C.; Wang, S. G.

    2018-04-01

    The interfacial structures, playing a critical role on the transport properties and the perpendicular magnetic anisotropy in thin films and multilayers, can be modified by inserting an ultrathin functional layer at the various interfaces. The anomalous Hall effect (AHE) in the multilayers with core structure of Ta/CoFeB/X/MgO/Ta (X: Hf or Pt) is tuned by interfacial catalytic engineering. The saturation anomalous Hall resistance (RAH) is increased by 16.5% with 0.1 nm Hf insertion compared with the reference sample without insertion. However, the RAH value is decreased by 9.0% with 0.1 nm Pt insertion. The interfacial states were characterized by the X-ray photoelectron spectroscopy (XPS). The XPS results indicate that a strong bonding between Hf and O for Hf insertion, but no bonding between Pt and O for Pt insertion. The bonding between metal and oxygen leads to various oxygen migration behavior at the interfaces. Therefore, the opposite behavior about the RAH originates from the different oxygen behavior due to various interfacial insertion. This work provides a new approach to manipulate spin transport property for the potential applications.

  15. Exciton ionization in multilayer transition-metal dichalcogenides

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm; Latini, Simone; Thygesen, Kristian Sommer

    2016-01-01

    Photodetectors and solar cells based on materials with strongly bound excitons rely crucially on field-assisted exciton ionization. We study the ionization process in multilayer transition-metal dichalcogenides (TMDs) within the Mott-Wannier model incorporating fully the pronounced anisotropy...

  16. Shape anisotropy: tensor distance to anisotropy measure

    Science.gov (United States)

    Weldeselassie, Yonas T.; El-Hilo, Saba; Atkins, M. S.

    2011-03-01

    Fractional anisotropy, defined as the distance of a diffusion tensor from its closest isotropic tensor, has been extensively studied as quantitative anisotropy measure for diffusion tensor magnetic resonance images (DT-MRI). It has been used to reveal the white matter profile of brain images, as guiding feature for seeding and stopping in fiber tractography and for the diagnosis and assessment of degenerative brain diseases. Despite its extensive use in DT-MRI community, however, not much attention has been given to the mathematical correctness of its derivation from diffusion tensors which is achieved using Euclidean dot product in 9D space. But, recent progress in DT-MRI has shown that the space of diffusion tensors does not form a Euclidean vector space and thus Euclidean dot product is not appropriate for tensors. In this paper, we propose a novel and robust rotationally invariant diffusion anisotropy measure derived using the recently proposed Log-Euclidean and J-divergence tensor distance measures. An interesting finding of our work is that given a diffusion tensor, its closest isotropic tensor is different for different tensor distance metrics used. We demonstrate qualitatively that our new anisotropy measure reveals superior white matter profile of DT-MR brain images and analytically show that it has a higher signal to noise ratio than fractional anisotropy.

  17. Effect of double layer thickness on magnetoelectric coupling in multiferroic BaTiO3-Bi0.95Gd0.05FeO3 multilayers

    Science.gov (United States)

    Hohenberger, S.; Lazenka, V.; Temst, K.; Selle, S.; Patzig, C.; Höche, T.; Grundmann, M.; Lorenz, M.

    2018-05-01

    The effect of double-layer thickness and partial substitution of Bi3+ by Gd3+ is demonstrated for multiferroic BaTiO3–BiFeO3 2–2 heterostructures. Multilayers of 15 double layers of BaTiO3 and Bi0.95Gd0.05FeO3 were deposited onto (0 0 1) oriented SrTiO3 substrates by pulsed laser deposition with various double layer thicknesses. X-ray diffraction and high resolution transmission electron microscopy investigations revealed a systematic strain tuning with layer thickness via coherently strained interfaces. The multilayers show increasingly enhanced magnetoelectric coupling with reduced double layer thickness. The maximum magnetoelectric coupling coefficient was measured to be as high as 50.8 V cm‑1 Oe‑1 in 0 T DC bias magnetic field at room temperature, and 54.9 V cm‑1 Oe‑1 above 3 T for the sample with the thinnest double layer thickness of 22.5 nm. This enhancement is accompanied by progressively increasing perpendicular magnetic anisotropy and compressive out-of-plane strain. To understand the origin of the enhanced magnetoelectric coupling in such multilayers, the temperature and magnetic field dependency of is discussed. The magnetoelectric performance of the Gd3+ substituted samples is found to be slightly enhanced when compared to unsubstituted BaTiO3–BiFeO3 multilayers of comparable double-layer thickness.

  18. Modeling Delamination of Interfacial Corner Cracks in Multilayered Structures

    DEFF Research Database (Denmark)

    Veluri, Badrinath (Badri); Jensen, Henrik Myhre

    2013-01-01

    Multilayered electronic components, typically of heterogeneous materials, delaminate under thermal and mechanical loading. A phenomenological model focused on modeling the shape of such interface cracks close to corners in layered interconnect structures for calculating the critical stress...

  19. Magnetic and transport properties of sputtered Gd-Y multilayers

    International Nuclear Information System (INIS)

    Freitas, P.P.; From, M.; Melo, L.V.

    1991-01-01

    Gd-Y-Gd multilayers were prepared that show a magnetoresistance enhancement for an Y layer separation of 30 A. This magnetoresistance enhancement is an interface effect and occurs in samples where some degree of antiferromagnetic coupling is present

  20. Structural and magnetic properties of granular CoPd multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Vivas, L.G.; Figueroa, A.I.; Bartolomé, F. [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Dept. de Física de la Materia Condensada, E-50009 Zaragoza (Spain); Rubín, J. [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Dept. de Ciencia y Tecnología de Materiales y Fluidos, E-50018 Zaragoza (Spain); García, L.M. [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Dept. de Física de la Materia Condensada, E-50009 Zaragoza (Spain); Deranlot, C.; Petroff, F. [Unité Mixte de Physique CNRS/Thales, F-91767 Palaiseau Cedex, France and Université Paris-Sud, F-191405 Orsay Cedex (France); Ruiz, L.; González-Calbet, J.M [Dept. de Química Inorgánica, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Brookes, N.B.; Wilhelm, F.; Rogalev, A. [European Synchrotron Radiation Facility (ESRF), CS40220, F-38043 Grenoble Cedex 9 (France); Bartolomé, J. [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Dept. de Física de la Materia Condensada, E-50009 Zaragoza (Spain)

    2016-02-15

    Multilayers of bimetallic CoPd alloyed and assembled nanoparticles, prepared by room temperature sequential sputtering deposition on amorphous alumina, were studied by means of high-resolution transmission electron microscopy, x-ray diffraction, SQUID-based magnetometry and x-ray magnetic circular dichroism. Alloying between Co and Pd in these nanoparticles gives rise to a high perpendicular magnetic anisotropy. Their magnetic properties are temperature dependent: at low temperature, the multilayers are ferromagnetic with a high coercive field; at intermediate temperature the behavior is of a soft-ferromagnet, and at higher temperature, the perpendicular magnetic anisotropy in the nanoparticles disappears. The magnetic orbital moment to spin moment ratio is enhanced compared with Co bare nanoparticles and Co fcc bulk. - Highlights: • CoPd granular nanolayers show perpendicular magnetic anisotropy. • Three magnetic phases are detected: hard-ferro, soft-ferro and superparamagnetism. • The nanoparticles have Co-core and CoPd alloy shell morphology.

  1. Structural and magnetic properties of granular CoPd multilayers

    International Nuclear Information System (INIS)

    Vivas, L.G.; Figueroa, A.I.; Bartolomé, F.; Rubín, J.; García, L.M.; Deranlot, C.; Petroff, F.; Ruiz, L.; González-Calbet, J.M; Brookes, N.B.; Wilhelm, F.; Rogalev, A.; Bartolomé, J.

    2016-01-01

    Multilayers of bimetallic CoPd alloyed and assembled nanoparticles, prepared by room temperature sequential sputtering deposition on amorphous alumina, were studied by means of high-resolution transmission electron microscopy, x-ray diffraction, SQUID-based magnetometry and x-ray magnetic circular dichroism. Alloying between Co and Pd in these nanoparticles gives rise to a high perpendicular magnetic anisotropy. Their magnetic properties are temperature dependent: at low temperature, the multilayers are ferromagnetic with a high coercive field; at intermediate temperature the behavior is of a soft-ferromagnet, and at higher temperature, the perpendicular magnetic anisotropy in the nanoparticles disappears. The magnetic orbital moment to spin moment ratio is enhanced compared with Co bare nanoparticles and Co fcc bulk. - Highlights: • CoPd granular nanolayers show perpendicular magnetic anisotropy. • Three magnetic phases are detected: hard-ferro, soft-ferro and superparamagnetism. • The nanoparticles have Co-core and CoPd alloy shell morphology.

  2. Multilayer scaffolds in orthopaedic tissue engineering.

    Science.gov (United States)

    Atesok, Kivanc; Doral, M Nedim; Karlsson, Jon; Egol, Kenneth A; Jazrawi, Laith M; Coelho, Paulo G; Martinez, Amaury; Matsumoto, Tomoyuki; Owens, Brett D; Ochi, Mitsuo; Hurwitz, Shepard R; Atala, Anthony; Fu, Freddie H; Lu, Helen H; Rodeo, Scott A

    2016-07-01

    The purpose of this study was to summarize the recent developments in the field of tissue engineering as they relate to multilayer scaffold designs in musculoskeletal regeneration. Clinical and basic research studies that highlight the current knowledge and potential future applications of the multilayer scaffolds in orthopaedic tissue engineering were evaluated and the best evidence collected. Studies were divided into three main categories based on tissue types and interfaces for which multilayer scaffolds were used to regenerate: bone, osteochondral junction and tendon-to-bone interfaces. In vitro and in vivo studies indicate that the use of stratified scaffolds composed of multiple layers with distinct compositions for regeneration of distinct tissue types within the same scaffold and anatomic location is feasible. This emerging tissue engineering approach has potential applications in regeneration of bone defects, osteochondral lesions and tendon-to-bone interfaces with successful basic research findings that encourage clinical applications. Present data supporting the advantages of the use of multilayer scaffolds as an emerging strategy in musculoskeletal tissue engineering are promising, however, still limited. Positive impacts of the use of next generation scaffolds in orthopaedic tissue engineering can be expected in terms of decreasing the invasiveness of current grafting techniques used for reconstruction of bone and osteochondral defects, and tendon-to-bone interfaces in near future.

  3. Status and limitations of multilayer X-ray interference structures

    International Nuclear Information System (INIS)

    Kortright, J.B.

    1996-01-01

    Trends in the performance of x-ray multilayer interference structures with periods ranging from 9 to 130 (angstrom) are reviewed. Analysis of near-normal incidence reflectance data vs photon energy reveals that the effective interface with σ in a static Debye-Waller model, describing interdiffusion and roughness, decreases as the multilayer period decreases, and reaches a lower limit of roughly 2 (angstrom). Specular reflectance and diffuse scattering from uncoated and multilayer-coated substrates having different roughness suggest that this lower limit results largely from substrate roughness. The increase in interface width with period thus results from increasing roughness of interdiffusion as the layer thickness increases

  4. Nanoconstriction spin-Hall oscillator with perpendicular magnetic anisotropy

    Science.gov (United States)

    Divinskiy, B.; Demidov, V. E.; Kozhanov, A.; Rinkevich, A. B.; Demokritov, S. O.; Urazhdin, S.

    2017-07-01

    We experimentally study spin-Hall nano-oscillators based on [Co/Ni] multilayers with perpendicular magnetic anisotropy. We show that these devices exhibit single-frequency auto-oscillations at current densities comparable to those for in-plane magnetized oscillators. The demonstrated oscillators exhibit large magnetization precession amplitudes, and their oscillation frequency is highly tunable by the electric current. These features make them promising for applications in high-speed integrated microwave circuits.

  5. Refractive index contrast in porous silicon multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Nava, R.; Mora, M.B. de la; Tagueena-Martinez, J. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Rio, J.A. del [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Centro Morelense de Innovacion y Transferencia Tecnologica, Consejo de Ciencia y Tecnologia del Estado de Morelos (Mexico)

    2009-07-15

    Two of the most important properties of a porous silicon multilayer for photonic applications are flat interfaces and a relative large refractive index contrast between layers in the optical wavelength range. In this work, we studied the effect of the current density and HF electrolyte concentration on the refractive index of porous silicon. With the purpose of increasing the refractive index contrast in a multilayer, the refractive index of porous silicon produced at low current was studied in detail. The current density applied to produce the low porosity layers was limited in order to keep the electrolyte flow through the multilayer structure and to avoid deformation of layer interfaces. We found that an electrolyte composed of hydrofluoric acid, ethanol and glycerin in a ratio of 3:7:1 gives a refractive index contrast around 1.3/2.8 at 600 nm. Several multilayer structures with this refractive index contrast were fabricated, such as dielectric Bragg mirrors and microcavities. Reflectance spectra of the structures show the photonic quality of porous silicon multilayers produced under these electrochemical conditions. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Modeling elastic anisotropy in strained heteroepitaxy.

    Science.gov (United States)

    Dixit, Gopal Krishna; Ranganathan, Madhav

    2017-09-20

    Using a continuum evolution equation, we model the growth and evolution of quantum dots in the heteroepitaxial Ge on Si(0 0 1) system in a molecular beam epitaxy unit. We formulate our model in terms of evolution due to deposition, and due to surface diffusion which is governed by a free energy. This free energy has contributions from surface energy, curvature, wetting effects and elastic energy due to lattice mismatch between the film and the substrate. In addition to anisotropy due to surface energy which favors facet formation, we also incorporate elastic anisotropy due to an underlying crystal lattice. The complicated elastic problem of the film-substrate system subjected to boundary conditions at the free surface, interface and the bulk substrate is solved by perturbation analysis using a small slope approximation. This permits an analysis of effects at different orders in the slope and sheds new light on the observed behavior. Linear stability analysis shows the early evolution of the instability towards dot formation. The elastic anisotropy causes a change in the alignment of dots in the linear regime, whereas the surface energy anisotropy changes the dot shapes at the nonlinear regime. Numerical simulation of the full nonlinear equations shows the evolution of the surface morphology. In particular, we show, for parameters of the [Formula: see text] [Formula: see text] on Si(0 0 1), the surface energy anisotropy dominates the shapes of the quantum dots, whereas their alignment is influenced by the elastic energy anisotropy. The anisotropy in elasticity causes a further elongation of the islands whose coarsening is interrupted due to [Formula: see text] facets on the surface.

  7. Modeling elastic anisotropy in strained heteroepitaxy

    Science.gov (United States)

    Krishna Dixit, Gopal; Ranganathan, Madhav

    2017-09-01

    Using a continuum evolution equation, we model the growth and evolution of quantum dots in the heteroepitaxial Ge on Si(0 0 1) system in a molecular beam epitaxy unit. We formulate our model in terms of evolution due to deposition, and due to surface diffusion which is governed by a free energy. This free energy has contributions from surface energy, curvature, wetting effects and elastic energy due to lattice mismatch between the film and the substrate. In addition to anisotropy due to surface energy which favors facet formation, we also incorporate elastic anisotropy due to an underlying crystal lattice. The complicated elastic problem of the film-substrate system subjected to boundary conditions at the free surface, interface and the bulk substrate is solved by perturbation analysis using a small slope approximation. This permits an analysis of effects at different orders in the slope and sheds new light on the observed behavior. Linear stability analysis shows the early evolution of the instability towards dot formation. The elastic anisotropy causes a change in the alignment of dots in the linear regime, whereas the surface energy anisotropy changes the dot shapes at the nonlinear regime. Numerical simulation of the full nonlinear equations shows the evolution of the surface morphology. In particular, we show, for parameters of the Ge0.25 Si0.75 on Si(0 0 1), the surface energy anisotropy dominates the shapes of the quantum dots, whereas their alignment is influenced by the elastic energy anisotropy. The anisotropy in elasticity causes a further elongation of the islands whose coarsening is interrupted due to facets on the surface.

  8. Anisoft - Advanced Treatment of Magnetic Anisotropy Data

    Science.gov (United States)

    Chadima, M.

    2017-12-01

    Since its first release, Anisoft (Anisotropy Data Browser) has gained a wide popularity in magnetic fabric community mainly due to its simple and user-friendly interface enabling very fast visualization of magnetic anisotropy tensors. Here, a major Anisoft update is presented transforming a rather simple data viewer into a platform offering an advanced treatment of magnetic anisotropy data. The updated software introduces new enlarged binary data format which stores both in-phase and out-of-phase (if measured) susceptibility tensors (AMS) or tensors of anisotropy of magnetic remanence (AMR) together with their respective confidence ellipses and values of F-tests for anisotropy. In addition to the tensor data, a whole array of specimen orientation angles, orientation of mesoscopic foliation(s) and lineation(s) is stored for each record enabling later editing or corrections. The input data may be directly acquired by AGICO Kappabridges (AMS) or Spinner Magnetometers (AMR); imported from various data formats, including the long-time standard binary ran-format; or manually created. Multiple anisotropy files can be combined together or split into several files by manual data selection or data filtering according to their values. Anisotropy tensors are conventionally visualized as principal directions (eigenvectors) in equal-area projection (stereoplot) together with a wide array of quantitative anisotropy parameters presented in histograms or in color-coded scatter plots showing mutual relationship of up to three quantitative parameters. When dealing with AMS in variable low fields, field-independent and field-dependent components of anisotropy can be determined (Hrouda 2009). For a group of specimens, individual principal directions can be contoured, or a mean tensor and respective confidence ellipses of its principal directions can be calculated using either the Hext-Jelinek (Jelinek 1978) statistics or the Bootstrap method (Constable & Tauxe 1990). Each graphical

  9. Critical currents in multilayered superconducting films

    International Nuclear Information System (INIS)

    Raffy, Helene

    1977-01-01

    The superconducting critical currents Isub(c) were measured as a function of magnetic field H and temperature T, on multilayered films. These films consist of alternating layers of two different superconductors S 1 and S 2 being a weaker superconductor acting as a flux pinning barrier region. A strong anisotropy was observed between the two situations where the magnetic field H is applied parallel or perpendicular to the layers. In the case discussed, there is a peak effect in the curves Isub(c)H well defined at the highest temperatures, and disappearing at low temperatures. The anisotropy of the critical current at constant field presents a maximum at a temperature T* close to the critical temperature Tsub(c 2 ) of S 2 [fr

  10. Magnetic pinning in superconductor-ferromagnet multilayers

    International Nuclear Information System (INIS)

    Bulaevskii, L. N.; Chudnovsky, E. M.; Maley, M. P.

    2000-01-01

    We argue that superconductor/ferromagnet multilayers of nanoscale period should exhibit strong pinning of vortices by the magnetic domain structure in magnetic fields below the coercive field when ferromagnetic layers exhibit strong perpendicular magnetic anisotropy. The estimated maximum magnetic pinning energy for single vortex in such a system is about 100 times larger than the pinning energy by columnar defects. This pinning energy may provide critical currents as high as 10 6 -10 7 A/cm 2 at high temperatures (but not very close to T c ) at least in magnetic fields below 0.1 T. (c) 2000 American Institute of Physics

  11. Magnetic pinning in superconductor-ferromagnet multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bulaevskii, L. N. [Department of Physics and Astronomy, CUNY Lehman College 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chudnovsky, E. M. [Department of Physics and Astronomy, CUNY Lehman College, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Maley, M. P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2000-05-01

    We argue that superconductor/ferromagnet multilayers of nanoscale period should exhibit strong pinning of vortices by the magnetic domain structure in magnetic fields below the coercive field when ferromagnetic layers exhibit strong perpendicular magnetic anisotropy. The estimated maximum magnetic pinning energy for single vortex in such a system is about 100 times larger than the pinning energy by columnar defects. This pinning energy may provide critical currents as high as 10{sup 6}-10{sup 7} A/cm{sup 2} at high temperatures (but not very close to T{sub c}) at least in magnetic fields below 0.1 T. (c) 2000 American Institute of Physics.

  12. Perpendicular magnetic anisotropy in Co2FeAl0.5Si0.5/MgO bottom electrodes for magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Li, X.Q.; Wu, Y.; Gao, S.; Xu, X.G.; Miao, J.; Jiang, Y.

    2013-01-01

    Perpendicular magnetic anisotropy (PMA) was achieved in annealed Co 2 FeAl 0.5 Si 0.5 (CFAS)/MgO-based multilayers with good thermal stability up to 400 °C and a large anisotropy energy density K u over 2.0 × 10 5 J/m 3 . The thickness of the full-Heusler CFAS film to maintain PMA is up to 4.8 nm in which the co-existence of disordered A2, ordered B2 and fully ordered L2 1 structures is observed. X-ray photoelectron spectroscopy analysis demonstrates that the origin of the PMA is the hybridization between Co 3d and O 2p orbitals at the CFAS/MgO interface. - Highlights: • We achieved perpendicular magnetic anisotropy (PMA) in Co 2 FeAl 0.5 Si 0.5 (4.8 nm) film; • L2 1 , B2 and A2 phases coexist in perpendicular magnetic anisotropic Co 2 FeAl 0.5 Si 0.5 ; • Magnetic properties have strong dependence on the annealing temperature; • The PMA is induced by the hybridization between Co-3d and O-2p orbitals

  13. Fabrication of multilayer nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Jasveer, E-mail: kaurjasveer89@gmail.com; Singh, Avtar; Kumar, Davinder [Department of Physics, Punjabi University Patiala, 147002, Punjab (India); Thakur, Anup; Kaur, Raminder, E-mail: raminder-k-saini@yahoo.com [Department of Basic and Applied Sciences, Punjabi University Patiala, 147002, Punjab (India)

    2016-05-06

    Multilayer nanowires were fabricated by potentiostate ectrodeposition template synthesis method into the pores of polycarbonate membrane. In present work layer by layer deposition of two different metals Ni and Cu in polycarbonate membrane having pore size of 600 nm were carried out. It is found that the growth of nanowires is not constant, it varies with deposition time. Scanning electron microscopy (SEM) is used to study the morphology of fabricated multilayer nanowires. An energy dispersive X-ray spectroscopy (EDS) results confirm the composition of multilayer nanowires. The result shows that multilayer nanowires formed is dense.

  14. Fabrication of multilayer nanowires

    International Nuclear Information System (INIS)

    Kaur, Jasveer; Singh, Avtar; Kumar, Davinder; Thakur, Anup; Kaur, Raminder

    2016-01-01

    Multilayer nanowires were fabricated by potentiostate ectrodeposition template synthesis method into the pores of polycarbonate membrane. In present work layer by layer deposition of two different metals Ni and Cu in polycarbonate membrane having pore size of 600 nm were carried out. It is found that the growth of nanowires is not constant, it varies with deposition time. Scanning electron microscopy (SEM) is used to study the morphology of fabricated multilayer nanowires. An energy dispersive X-ray spectroscopy (EDS) results confirm the composition of multilayer nanowires. The result shows that multilayer nanowires formed is dense.

  15. Oblique roughness replication in strained SiGe/Si multilayers

    NARCIS (Netherlands)

    Holy, V.; Darhuber, A.A.; Stangl, J.; Bauer, G.; Nützel, J.-F.; Abstreiter, G.

    1998-01-01

    The replication of the interface roughness in SiGe/Si multilayers grown on miscut Si(001) substrates has been studied by means of x-ray reflectivity reciprocal space mapping. The interface profiles were found to be highly correlated and the direction of the maximal replication was inclined with

  16. Study on the depth profile analysis of Fe/Co intermixing in [SmCo{sub 5}/Fe]{sub 11} magnetic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, P., E-mail: psdrdo@gmail.com [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Hsu, Jen-Hwa, E-mail: jhhsu@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Perumal, A.; Gayen, Anabil [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Reddy, G.L.N.; Kumar, Sanjiv [National Centre for Compositional Characterization of Materials, Bhabha Atomic Research Centre, ECIL Post, Hyderabad 500062 (India); Kamat, S.V. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)

    2014-09-01

    Multilayer films were sputtered on Si (1 0 0) substrate by following a layer sequence of Cr (10 nm)/[Fe (4 nm)/SmCo{sub 5} (20 nm)]{sub 11}/Cr (90 nm) at room temperature and subsequently, subjected to two-stage annealing. The phase composition, the extent of inter-diffusion at the SmCo{sub 5}/Fe interfaces and the magnetic properties of multilayered samples were investigated by X-ray diffraction (XRD), RBS and super-conducting quantum interference device (SQUID), respectively. The XRD studies showed the crystallization of SmCo{sub 5}-phase in the hard layer along with a bcc-Fe (Co)-phase in the soft layer, while the RBS depth profile analysis revealed the changes that occur in the effective Fe-layer thickness and diffused Co-content as minimal for the Fe-layer index, n{sub Fe}≤5. A single-phase behavior associated with strong in-plane anisotropy was evidenced with the SQUID measurements. The observed remanence enhancement (1020 kA/m) and energy product value (286 kJ/m{sup 3}) in these multilayers are discussed in the context of Fe-layer thickness and diffused Co-content.

  17. EUV multilayer mirrors with enhanced stability

    Science.gov (United States)

    Benoit, Nicolas; Yulin, Sergiy; Feigl, Torsten; Kaiser, Norbert

    2006-08-01

    The application of multilayer optics in EUV lithography requires not only the highest possible normal-incidence reflectivity but also a long-term thermal and radiation stability at operating temperatures. This requirement is most important in the case of the collector mirror of the illumination system close to the EUV source where a short-time decrease in reflectivity is most likely. Mo/Si multilayer mirrors, designed for high normal reflectivity at the wavelength of 13.5 nm and deposited by dc magnetron sputtering, were directly exposed to EUV radiation without mitigation system. They presented a loss of reflectivity of more than 18% after only 8 hours of irradiation by a Xe-discharge source. Another problem of Mo/Si multilayers is the instability of reflectivity and peak wavelength under high heat load. It becomes especially critical at temperatures above 200°C, where interdiffusion between the molybdenum and the silicon layers is observed. The development of high-temperature multilayers was focused on two alternative Si-based systems: MoSi II/Si and interface engineered Mo/C/Si/C multilayer mirrors. The multilayer designs as well as the deposition parameters of all systems were optimized in terms of high peak reflectivity (>= 60 %) at a wavelength of 13.5 nm and high thermal stability. Small thermally induced changes of the MoSi II/Si multilayer properties were found but they were independent of the annealing time at all temperatures examined. A wavelength shift of -1.7% and a reflectivity drop of 1.0% have been found after annealing at 500°C for 100 hours. The total degradation of optical properties above 650°C can be explained by a recrystallization process of MoSi II layers.

  18. Magnetic properties of sputtered Permalloy/molybdenum multilayers

    International Nuclear Information System (INIS)

    Romera, M.; Ciudad, D.; Maicas, M.; Aroca, C.; Ranchal, R.

    2011-01-01

    In this work, we report the magnetic properties of sputtered Permalloy (Py: Ni 80 Fe 20 )/molybdenum (Mo) multilayer thin films. We show that it is possible to maintain a low coercivity and a high permeability in thick sputtered Py films when reducing the out-of-plane component of the anisotropy by inserting thin film spacers of a non-magnetic material like Mo. For these kind of multilayers, we have found coercivities which are close to those for single layer films with no out-of-plane anisotropy. The coercivity is also dependent on the number of layers exhibiting a minimum value when each single Py layer has a thickness close to the transition thickness between Neel and Bloch domain walls.

  19. Structural and magnetic properties of granular CoPd multilayers

    Science.gov (United States)

    Vivas, L. G.; Figueroa, A. I.; Bartolomé, F.; Rubín, J.; García, L. M.; Deranlot, C.; Petroff, F.; Ruiz, L.; González-Calbet, J. M.; Brookes, N. B.; Wilhelm, F.; Rogalev, A.; Bartolomé, J.

    2016-02-01

    Multilayers of bimetallic CoPd alloyed and assembled nanoparticles, prepared by room temperature sequential sputtering deposition on amorphous alumina, were studied by means of high-resolution transmission electron microscopy, x-ray diffraction, SQUID-based magnetometry and x-ray magnetic circular dichroism. Alloying between Co and Pd in these nanoparticles gives rise to a high perpendicular magnetic anisotropy. Their magnetic properties are temperature dependent: at low temperature, the multilayers are ferromagnetic with a high coercive field; at intermediate temperature the behavior is of a soft-ferromagnet, and at higher temperature, the perpendicular magnetic anisotropy in the nanoparticles disappears. The magnetic orbital moment to spin moment ratio is enhanced compared with Co bare nanoparticles and Co fcc bulk.

  20. Plasma sheet pressure anisotropies

    International Nuclear Information System (INIS)

    Stiles, G.S.; Hones, E.W. Jr; Bame, S.J.; Asbridge, J.R.

    1978-01-01

    The ecliptic plane components of the pressure tensors for low-energy ( or =1.2 approximately 25% of the time. Due to the low energy density of the electrons, however, this anisotropy is not itself sufficient to balance the tension of the magnetic field

  1. CMB anisotropies interpolation

    NARCIS (Netherlands)

    Zinger, S.; Delabrouille, Jacques; Roux, Michel; Maitre, Henri

    2010-01-01

    We consider the problem of the interpolation of irregularly spaced spatial data, applied to observation of Cosmic Microwave Background (CMB) anisotropies. The well-known interpolation methods and kriging are compared to the binning method which serves as a reference approach. We analyse kriging

  2. Technique for etching monolayer and multilayer materials

    Science.gov (United States)

    Bouet, Nathalie C. D.; Conley, Raymond P.; Divan, Ralu; Macrander, Albert

    2015-10-06

    A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi.sub.2/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF.sub.3, Cl.sub.2, and O.sub.2 with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.

  3. Multilayer Brain Networks

    Science.gov (United States)

    Vaiana, Michael; Muldoon, Sarah Feldt

    2018-01-01

    The field of neuroscience is facing an unprecedented expanse in the volume and diversity of available data. Traditionally, network models have provided key insights into the structure and function of the brain. With the advent of big data in neuroscience, both more sophisticated models capable of characterizing the increasing complexity of the data and novel methods of quantitative analysis are needed. Recently, multilayer networks, a mathematical extension of traditional networks, have gained increasing popularity in neuroscience due to their ability to capture the full information of multi-model, multi-scale, spatiotemporal data sets. Here, we review multilayer networks and their applications in neuroscience, showing how incorporating the multilayer framework into network neuroscience analysis has uncovered previously hidden features of brain networks. We specifically highlight the use of multilayer networks to model disease, structure-function relationships, network evolution, and link multi-scale data. Finally, we close with a discussion of promising new directions of multilayer network neuroscience research and propose a modified definition of multilayer networks designed to unite and clarify the use of the multilayer formalism in describing real-world systems.

  4. A refined model for characterizing x-ray multilayers

    International Nuclear Information System (INIS)

    Oren, A.L.; Henke, B.L.

    1987-12-01

    The ability to quickly and accurately characterize arbitrary multilayers is very valuable for not only can we use the characterizations to predict the reflectivity of a multilayer for any soft x-ray wavelength, we also can generalize the results to apply to other multilayers of the same type. In addition, we can use the characterizations as a means of evaluating various sputtering environments and refining sputtering techniques to obtain better multilayers. In this report we have obtained improved characterizations for sample molybdenum-silicon and vanadium-silicon multilayers. However, we only examined five crystals overall, so the conclusions that we could draw about the structure of general multilayers is limited. Research involving many multilayers manufactured under the same sputtering conditions is clearly in order. In order to best understand multilayer structures it may be necessary to further refine our model, e.g., adopting a Gaussian form for the interface regions. With such improvements we can expect even better agreement with experimental values and continued concurrence with other characterization techniques. 18 refs., 30 figs., 7 tabs

  5. Development of a tensile-stress-induced anisotropy in amorphous magnetic thin films

    International Nuclear Information System (INIS)

    Mandal, K.; Vazquez, M.; Garcia, D.; Castano, F.J.; Prados, C.; Hernando, A.

    2000-01-01

    Magnetic anisotropy was induced in positive magnetostrictive Fe 80 B 20 and negative magnetostrictive Co 75 Si 15 B 10 thin films by developing a tensile stress within the samples. The films were grown on the concave surfaces of mechanically bowed glass substrates. On releasing the substrates from the substrate holders, a tensile stress was developed within the samples that modified the domain structure. As a result of it, a magnetic easy axis parallel to the direction of the stress was induced in FeB sample whereas in CoSiB sample the induced easy axis was perpendicular to the direction of the developed stress. To produce magnetic multilayers with crossed anisotropy, FeB/CoSiB bilayers and FeB/Cu/CoSiB trilayers were grown on bowed substrates. The study of magnetic properties of the multilayers indicates the development of crossed anisotropy within them, particularly when the magnetic layers are separated by a nonmagnetic Cu layer

  6. Elastic Anisotropy of Basalt

    Science.gov (United States)

    Becker, K.; Shapiro, S.; Stanchits, S.; Dresen, G.; Kaselow, A.; Vinciguerra, S.

    2005-12-01

    Elastic properties of rocks are sensitive to changes of the in-situ stress and damage state. In particular, seismic velocities are strongly affected by stress-induced formation and deformation of cracks or shear-enhanced pore collapse. The effect of stress on seismic velocities as a result of pore space deformation in isotropic rock at isostatic compression may be expressed by the equation: A+K*P-B*exp (-D*P) (1), where P=Pc-Pp is the effective pressure, the pure difference between confining pressure and pore pressure. The parameter A, K, B and D describe material constants determined using experimental data. The physical meaning of the parameters is given by Shapiro (2003, in Geophysics Vol.68(Nr.2)). Parameter D is related to the stress sensitivity of the rock. A similar relation was derived by Shapiro and Kaselow (2005, in Geophysics in press) for weak anisotropic rocks under arbitrary load. They describe the stress dependent anisotropy in terms of Thomson's (1986, in Geophysics, Vol. 51(Nr.10)) anisotropy parameters ɛ and γ as a function of stress in the case of an initially isotropic rock: ɛ ∝ E2-E3, γ ∝ E3-E2 (2) with Ei=exp (D*Pi). The exponential terms Ei are controlled by the effective stress components Pi. To test this relation, we have conducted a series of triaxial compression tests on dry samples of initially isotropic Etnean Basalt in a servo-controlled MTS loading frame equipped with a pressure cell. Confining pressure was 60, 40 and 20 MPa. Samples were 5 cm in diameter and 10 cm in length. Elastic anisotropy was induced by axial compression of the samples through opening and growth of microcracks predominantly oriented parallel to the sample axis. Ultrasonic P- and S- wave velocities were monitored parallel and normal to the sample axis by an array of 20 piezoceramic transducers glued to the surface. Preamplified full waveform signals were stored in two 12 channel transient recorders. According to equation 2 the anisotropy parameters are

  7. Covalently attached multilayer assemblies of diazo-resins and binuclear cobalt phthalocyanines

    International Nuclear Information System (INIS)

    Li Xiaofang; Zhao Shuang; Yang Min; Sun Changqing; Guo, Liping

    2005-01-01

    By using the ionic self-assembly technique, ordered multilayer thin films composed of diazo-resin (DAR) as polycation and water-soluble binuclear cobalt phthalocyaninehexasulfonate (Bi-CoPc) as polyanion were alternately fabricated on quartz, CaF 2 and glassy carbon electrodes (GCEs). Upon ultraviolet irradiation, the adjacent interface of the multilayer films reacted to form a covalently cross-linking structure. The obtained thin films were characterized by ultraviolet (UV)-vis, Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), atomic force microscope (AFM), surface photovoltage spectra (SPS), and cyclic voltammetry. The results show that the uniform, highly stable and ordered multilayer thin films were formed. The linkage nature between the adjacent interface of the multilayer films converts from ionic to covalent, and, as a result, the stability of the multilayer thin films dramatically improved. The multilayer thin films on GCEs also exhibited excellent electrochemical behavior

  8. Covalently attached multilayer assemblies of diazo-resins and binuclear cobalt phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaofang [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130023 (China); Zhao Shuang [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130023 (China); Yang Min [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130023 (China); Sun Changqing [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130023 (China)]. E-mail: sunchq@mail.jlu.edu.cn; Guo, Liping [Department of Chemistry, Northeast Normal University, Changchun 130024 (China)

    2005-05-01

    By using the ionic self-assembly technique, ordered multilayer thin films composed of diazo-resin (DAR) as polycation and water-soluble binuclear cobalt phthalocyaninehexasulfonate (Bi-CoPc) as polyanion were alternately fabricated on quartz, CaF{sub 2} and glassy carbon electrodes (GCEs). Upon ultraviolet irradiation, the adjacent interface of the multilayer films reacted to form a covalently cross-linking structure. The obtained thin films were characterized by ultraviolet (UV)-vis, Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), atomic force microscope (AFM), surface photovoltage spectra (SPS), and cyclic voltammetry. The results show that the uniform, highly stable and ordered multilayer thin films were formed. The linkage nature between the adjacent interface of the multilayer films converts from ionic to covalent, and, as a result, the stability of the multilayer thin films dramatically improved. The multilayer thin films on GCEs also exhibited excellent electrochemical behavior.

  9. Emergent magnetism at transition-metal–nanocarbon interfaces

    Science.gov (United States)

    Al Ma’Mari, Fatma; Rogers, Matthew; Alghamdi, Shoug; Moorsom, Timothy; Lee, Stephen; Prokscha, Thomas; Luetkens, Hubertus; Valvidares, Manuel; Flokstra, Machiel; Stewart, Rhea; Ali, Mannan; Burnell, Gavin; Hickey, B. J.

    2017-01-01

    Charge transfer at metallo–molecular interfaces may be used to design multifunctional hybrids with an emergent magnetization that may offer an eco-friendly and tunable alternative to conventional magnets and devices. Here, we investigate the origin of the magnetism arising at these interfaces by using different techniques to probe 3d and 5d metal films such as Sc, Mn, Cu, and Pt in contact with fullerenes and rf-sputtered carbon layers. These systems exhibit small anisotropy and coercivity together with a high Curie point. Low-energy muon spin spectroscopy in Cu and Sc–C60 multilayers show a quick spin depolarization and oscillations attributed to nonuniform local magnetic fields close to the metallo–carbon interface. The hybridization state of the carbon layers plays a crucial role, and we observe an increased magnetization as sp3 orbitals are annealed into sp2−π graphitic states in sputtered carbon/copper multilayers. X-ray magnetic circular dichroism (XMCD) measurements at the carbon K edge of C60 layers in contact with Sc films show spin polarization in the lowest unoccupied molecular orbital (LUMO) and higher π*-molecular levels, whereas the dichroism in the σ*-resonances is small or nonexistent. These results support the idea of an interaction mediated via charge transfer from the metal and dz–π hybridization. Thin-film carbon-based magnets may allow for the manipulation of spin ordering at metallic surfaces using electrooptical signals, with potential applications in computing, sensors, and other multifunctional magnetic devices. PMID:28507160

  10. Emergent magnetism at transition-metal-nanocarbon interfaces.

    Science.gov (United States)

    Al Ma'Mari, Fatma; Rogers, Matthew; Alghamdi, Shoug; Moorsom, Timothy; Lee, Stephen; Prokscha, Thomas; Luetkens, Hubertus; Valvidares, Manuel; Teobaldi, Gilberto; Flokstra, Machiel; Stewart, Rhea; Gargiani, Pierluigi; Ali, Mannan; Burnell, Gavin; Hickey, B J; Cespedes, Oscar

    2017-05-30

    Charge transfer at metallo-molecular interfaces may be used to design multifunctional hybrids with an emergent magnetization that may offer an eco-friendly and tunable alternative to conventional magnets and devices. Here, we investigate the origin of the magnetism arising at these interfaces by using different techniques to probe 3d and 5d metal films such as Sc, Mn, Cu, and Pt in contact with fullerenes and rf-sputtered carbon layers. These systems exhibit small anisotropy and coercivity together with a high Curie point. Low-energy muon spin spectroscopy in Cu and Sc-C 60 multilayers show a quick spin depolarization and oscillations attributed to nonuniform local magnetic fields close to the metallo-carbon interface. The hybridization state of the carbon layers plays a crucial role, and we observe an increased magnetization as sp 3 orbitals are annealed into sp 2 -π graphitic states in sputtered carbon/copper multilayers. X-ray magnetic circular dichroism (XMCD) measurements at the carbon K edge of C 60 layers in contact with Sc films show spin polarization in the lowest unoccupied molecular orbital (LUMO) and higher π*-molecular levels, whereas the dichroism in the σ*-resonances is small or nonexistent. These results support the idea of an interaction mediated via charge transfer from the metal and dz -π hybridization. Thin-film carbon-based magnets may allow for the manipulation of spin ordering at metallic surfaces using electrooptical signals, with potential applications in computing, sensors, and other multifunctional magnetic devices.

  11. Spin reorientation transition in Co/Au multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Quispe-Marcatoma, J., E-mail: jquispem@unmsm.edu.pe [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, P.O. Box 14-0149, Lima 14, Perú (Peru); Tarazona, H. [Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, P.O. Box 14-0149, Lima 14, Perú (Peru); Pandey, B. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Department of Applied Science, Symbiosis Institute of Technology, SIU, Lavale, Pune 412 115, India. (India); Sousa, M.A. de [Instituto de Física, Universidade Federal de Goiás, Goiânia 74001-970 (Brazil); Carvalho, M. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Landauro, C.V. [Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, P.O. Box 14-0149, Lima 14, Perú (Peru); Pelegrini, F. [Instituto de Física, Universidade Federal de Goiás, Goiânia 74001-970 (Brazil); Baggio Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil)

    2014-10-01

    We report a study about the spin reorientation transition (SRT) from perpendicular easy axis to in-plane easy axis of magnetization in Co/Au multilayers. A series of multilayers of Si/Au(100 Å)/{[Co(t_C_o)/Au(20 Å)]_2_0}/Au(50 Å) family were studied, with Co layer thickness varying between 6 Å to 30 Å. The thickness of the Au layer was chosen large enough in order to minimize the interlayer exchange coupling between Co layers. In such thick Au-layer samples the magnetic properties are mainly the result of competition between interlayer magnetostatic coupling due to stray field, perpendicular magnetic anisotropy and shape anisotropy. The effective anisotropy constant K{sub eff} and the second order anisotropy K{sub 2} were deduced from the fit of the resonant magnetic field obtained from out of plane dependence Ferromagnetic Resonance (FMR) experiments. To study the SRT, we have plotted the phase diagram between K{sub eff} and K{sub 2}. The results show that SRT occurs through the metastable region with K{sub 2} ≤ −½ K{sub eff}, (K{sub eff} > 0). It is interesting to note that FMR shows the coexistence of two modes with different anisotropy for small Co thickness, while for thick Co layers the modes have the same anisotropy. Moreover, in thick Co layer samples, volume and surface spin wave resonance (SWR) modes were also excited by the microwave field, around the perpendicular FMR geometry, giving a clear evidence of a magnetic coupling between the Co layers. - Highlights: • Co/Au multilayers with varying Co layer thickness are prepared by DC-magnetron sputtering. • The spin reorientation transition (SRT) and flipping of magnetic moment are studied. • Effective anisotropy constant (K) and 2nd order anisotropy constant (K{sub 2}) are calculated. • K Vs K{sub 2} plot showed that SRT occurs through the metastable region with K{sub 2} ≤ −½ K, (K > 0). • Ferromagnetic Resonance spectra showed the coexistence of two resonance modes.

  12. Quarkonium dissociation by anisotropy

    Science.gov (United States)

    Chernicoff, Mariano; Fernández, Daniel; Mateos, David; Trancanelli, Diego

    2013-01-01

    We compute the screening length for quarkonium mesons moving through an anisotropic, strongly coupled mathcal{N} = 4 super Yang-Mills plasma by means of its gravity dual. We present the results for arbitrary velocities and orientations of the mesons, as well as for arbitrary values of the anisotropy. The anisotropic screening length can be larger or smaller than the isotropic one, and this depends on whether the comparison is made at equal temperatures or at equal entropy densities. For generic motion we find that: (i) mesons dissociate above a certain critical value of the anisotropy, even at zero temperature; (ii) there is a limiting velocity for mesons in the plasma, even at zero temperature; (iii) in the ultra-relativistic limit the screening length scales as (1 - v 2)ɛ with ɛ = 1 /2, in contrast with the isotropic result ɛ = 1 /4.

  13. Structural and magnetic properties of Ce/Fe and Ce/FeCoV multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Tixier, S; Boeni, P [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Mannix, D; Stirling, W G [Liverpool Univ. (United Kingdom); Lander, G H

    1997-09-01

    Ce/Fe and Ce/FeCoV multilayers have been grown by magnetron sputtering. The interfaces are well defined and the layers are crystalline down to an individual layer thickness of 20 A. Ce/FeCoV multilayers show sharper interfaces than Ce/Fe but some loss of crystallinity is observed. Hysteresis loops obtained by SQUID show different behaviour of the bulk magnetisation as a function of the layer thickness. Fe moments are found by Moessbauer spectroscopy to be perpendicular to the interfaces for multilayers with small periodicity. (author) 2 figs., 2 refs.

  14. Supernovae anisotropy power spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Ghodsi, Hoda; Baghram, Shant [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Habibi, Farhang, E-mail: h.ghodsi@mehr.sharif.ir, E-mail: baghram@sharif.edu, E-mail: habibi@lal.in2p3.fr [LAL-IN2P3/CNRS, BP 34, 91898 Orsay Cedex (France)

    2017-10-01

    We contribute another anisotropy study to this field of research using Type Ia supernovae (SNe Ia). In this work, we utilise the power spectrum calculation method and apply it to both the current SNe Ia data and simulation. Using the Union2.1 data set at all redshifts, we compare the spectrum of the residuals of the observed distance moduli to that expected from an isotropic universe affected by the Union2.1 observational uncertainties at low multipoles. Through this comparison we find a dipolar anisotropy with tension of less that 2σ towards l = 171° ± 21° and b = −26° ± 28° which is mainly induced by anisotropic spatial distribution of the SNe with z > 0.2 rather than being a cosmic effect. Furthermore, we find a tension of ∼ 4σ at ℓ = 4 between the two spectra. Our simulations are constructed with the characteristics of the upcoming surveys like the Large Synoptic Survey Telescope (LSST), which shall bring us the largest SNe Ia collection to date. We make predictions for the amplitude of a possible dipolar anisotropy that would be detectable by future SNe Ia surveys.

  15. Achieving perpendicular anisotropy in half-metallic Heusler alloys for spin device applications

    Science.gov (United States)

    Munira, Kamaram; Romero, Jonathon; Butler, William H.

    2014-05-01

    Various full Heusler alloys are interfaced with MgO and the magnetic properties of the Heusler-MgO junctions are studied. Next to MgO, the cubic Heusler system distorts to a tetragonal one, thereby inducing an anisotropy. The half-metallicity and nature of anisotropy (in-plane or perpendicular) in the Heusler-MgO system is governed mostly by the interface Heusler layers. There is a trend that Mn-O bonding near the MgO-Heusler junction results in perpendicular anisotropy. The ability to remain half-metallic and have perpendicular anisotropy makes some of these alloys potential candidates as free-layers in Spin Transfer Torque Random Access Memory (STT-RAM) devices, particularly, Cr2MnAs-MgO system with MnAs interface layers and Co2MnSi-MgO system with Mn2 interface layers.

  16. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    Kumar, N.; Radhika, R.; Kozakov, A.T.; Pandian, R.; Chakravarty, S.; Ravindran, T.R.; Dash, S.; Tyagi, A.K.

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient

  17. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N., E-mail: niranjan@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Radhika, R. [Crystal Growth Centre, Anna University, Chennai (India); Kozakov, A.T. [Research Institute of Physics, Southern Federal University, Rostov-on-Don (Russian Federation); Pandian, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Chakravarty, S. [UGC-DAE CSR, Kalpakkam (India); Ravindran, T.R.; Dash, S.; Tyagi, A.K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

  18. Magnetization states and magnetization processes in nanostructures: from a single layer to multilayers

    Czech Academy of Sciences Publication Activity Database

    Maziewski, A.; Fassbender, J.; Kisielewski, J.; Kisielewski, M.; Kurant, Z.; Mazalski, P.; Stobiecki, F.; Stupakiewicz, A.; Sveklo, I.; Tekielak, M.; Wawro, A.; Zablotskyy, Vitaliy A.

    2014-01-01

    Roč. 211, č. 5 (2014), s. 1005-1018 ISSN 1862-6300 R&D Projects: GA ČR GA13-18993S Institutional support: RVO:68378271 Keywords : light and ions irradiation effects * magnetic anisotropy * magnetic domains * magnetic ordering * magnetic ultrathin films and multilayers Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.616, year: 2014

  19. Transmission fingerprints in quasiperiodic magnonic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, I.P. [Departamento de Ensino Superior, Instituto Federal de Educacao, Ciencia e Tecnologia do Maranhao, Imperatriz-MA 65919-050 (Brazil); Departamento de Fisica, Universidade Federal do Rio Grande do Norte, Natal-RN 59072-970 (Brazil); Vasconcelos, M.S. [Escola de Ciencias e Tecnologia, Universidade Federal do Rio Grande do Norte, Natal-RN 59072-970 (Brazil); Bezerra, C.G., E-mail: cbezerra@dfte.ufrn.br [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, Natal-RN 59072-970 (Brazil)

    2011-12-15

    In this paper we investigated the influence of mirror symmetry on the transmission spectra of quasiperiodic magnonic multilayers arranged according to Fibonacci, Thue-Morse and double period quasiperiodic sequences. We consider that the multilayers composed of two simple cubic Heisenberg ferromagnets with bulk exchange constants J{sub A} and J{sub B} and spin quantum numbers S{sub A} and S{sub B}, respectively. The multilayer structure is surrounded by two semi-infinite slabs of a third Heisenberg ferromagnetic material with exchange constant J{sub C} and spin quantum number S{sub C}. For simplicity, the lattice constant has the same value a in each material, corresponding to epitaxial growth at the interfaces. The transfer matrix treatment was used for the exchange-dominated regime, taking into account the random phase approximation (RPA). Our numerical results illustrate the effects of mirror symmetry on (i) transmission spectra and (ii) transmission fingerprints. - Highlights: > We model quasiperiodic magnetic multilayers presenting mirror symmetry. > We investigated the allowed and forbidden bands of magnonic transmission. > Transmission return maps show the influence of mirror symmetry. > Mirror symmetry has no effect on the Fibonacci case. > Mirror symmetry does have effect on the Thue-Morse and double period cases.

  20. Transmission fingerprints in quasiperiodic magnonic multilayers

    International Nuclear Information System (INIS)

    Coelho, I.P.; Vasconcelos, M.S.; Bezerra, C.G.

    2011-01-01

    In this paper we investigated the influence of mirror symmetry on the transmission spectra of quasiperiodic magnonic multilayers arranged according to Fibonacci, Thue-Morse and double period quasiperiodic sequences. We consider that the multilayers composed of two simple cubic Heisenberg ferromagnets with bulk exchange constants J A and J B and spin quantum numbers S A and S B , respectively. The multilayer structure is surrounded by two semi-infinite slabs of a third Heisenberg ferromagnetic material with exchange constant J C and spin quantum number S C . For simplicity, the lattice constant has the same value a in each material, corresponding to epitaxial growth at the interfaces. The transfer matrix treatment was used for the exchange-dominated regime, taking into account the random phase approximation (RPA). Our numerical results illustrate the effects of mirror symmetry on (i) transmission spectra and (ii) transmission fingerprints. - Highlights: → We model quasiperiodic magnetic multilayers presenting mirror symmetry. → We investigated the allowed and forbidden bands of magnonic transmission. → Transmission return maps show the influence of mirror symmetry. → Mirror symmetry has no effect on the Fibonacci case. → Mirror symmetry does have effect on the Thue-Morse and double period cases.

  1. Magnetostatics and dynamics of ion irradiatied NiFe/Ta multilayer films studied by vector network analyzer ferromagnetic resonance

    International Nuclear Information System (INIS)

    Marko, Daniel

    2010-01-01

    In the present work, the implications of ion irradiation on the magnetostatic and dynamic properties of soft magnetic Py/Ta (Py=Permalloy: Ni 80 Fe 20 ) single and multilayer films have been investigated with the main objective of finding a way to determine their saturation magnetization. Both polar magneto-optical Kerr effect (MOKE) and vector network analyzer ferromagnetic resonance (VNA-FMR) measurements have proven to be suitable methods to determine μ 0 M S , circumventing the problem of the unknown effective magnetic volume that causes conventional techniques such as SQUID or VSM to fail. Provided there is no perpendicular anisotropy contribution in the samples, the saturation magnetization can be determined even in the case of strong interfacial mixing due to an inherently high number of Py/Ta interfaces and/or ion irradiation with high fluences. Another integral part of this work has been to construct a VNA-FMR spectrometer capable of performing both azimuthal and polar angle-dependent measurements using a magnet strong enough to saturate samples containing iron. Starting from scratch, this comprised numerous steps such as developing a suitable coplanar waveguide design, and writing the control, evaluation, and fitting software. With both increasing ion fluence and number of Py/Ta interfaces, a decrease of saturation magnetization has been observed. In the case of the 10 x Py samples, an immediate decrease of μ 0 M S already sets in at small ion fluences. However, for the 1 x Py and 5 x Py samples, the saturation magnetization remains constant up to a certain ion fluence, but then starts to rapidly decrease. Ne ion irradiation causes a mixing and broadening of the interfaces. Thus, the Py/Ta stacks undergo a transition from being polycrystalline to amorphous at a critical fluence depending on the number of interfaces. The saturation magnetization is found to vanish at a Ta concentration of about 10-15 at.% in the Py layers. The samples possess a small

  2. Magnetostatics and dynamics of ion irradiatied NiFe/Ta multilayer films studied by vector network analyzer ferromagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Marko, Daniel

    2010-11-25

    In the present work, the implications of ion irradiation on the magnetostatic and dynamic properties of soft magnetic Py/Ta (Py=Permalloy: Ni{sub 80}Fe{sub 20}) single and multilayer films have been investigated with the main objective of finding a way to determine their saturation magnetization. Both polar magneto-optical Kerr effect (MOKE) and vector network analyzer ferromagnetic resonance (VNA-FMR) measurements have proven to be suitable methods to determine {mu}{sub 0}M{sub S}, circumventing the problem of the unknown effective magnetic volume that causes conventional techniques such as SQUID or VSM to fail. Provided there is no perpendicular anisotropy contribution in the samples, the saturation magnetization can be determined even in the case of strong interfacial mixing due to an inherently high number of Py/Ta interfaces and/or ion irradiation with high fluences. Another integral part of this work has been to construct a VNA-FMR spectrometer capable of performing both azimuthal and polar angle-dependent measurements using a magnet strong enough to saturate samples containing iron. Starting from scratch, this comprised numerous steps such as developing a suitable coplanar waveguide design, and writing the control, evaluation, and fitting software. With both increasing ion fluence and number of Py/Ta interfaces, a decrease of saturation magnetization has been observed. In the case of the 10 x Py samples, an immediate decrease of {mu}{sub 0}M{sub S} already sets in at small ion fluences. However, for the 1 x Py and 5 x Py samples, the saturation magnetization remains constant up to a certain ion fluence, but then starts to rapidly decrease. Ne ion irradiation causes a mixing and broadening of the interfaces. Thus, the Py/Ta stacks undergo a transition from being polycrystalline to amorphous at a critical fluence depending on the number of interfaces. The saturation magnetization is found to vanish at a Ta concentration of about 10-15 at.% in the Py layers

  3. Perpendicular magnetic anisotropy in Ta|Co40Fe40B20|MgAl2O4 structures and perpendicular CoFeB|MgAl2O4|CoFeB magnetic tunnel junction

    KAUST Repository

    Tao, B. S.

    2014-09-08

    Magnetic properties of Co40Fe40B20(CoFeB) thin films sandwiched between Ta and MgAl2O4layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl2O4structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy Ki=1.22erg/cm2, which further increases to 1.30erg/cm2after annealing, while MgAl2O4/CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0nm, while that for top CoFeB layer is between 0.8 and 1.4nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl2O4/CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.

  4. Perpendicular magnetic anisotropy in Ta|Co40Fe40B20|MgAl2O4 structures and perpendicular CoFeB|MgAl2O4|CoFeB magnetic tunnel junction

    KAUST Repository

    Tao, B. S.; Li, D. L.; Yuan, Z. H.; Liu, H. F.; Ali, S. S.; Feng, J. F.; Wei, H. X.; Han, X. F.; Liu, Y.; Zhao, Y. G.; Zhang, Q.; Guo, Zaibing; Zhang, Xixiang

    2014-01-01

    Magnetic properties of Co40Fe40B20(CoFeB) thin films sandwiched between Ta and MgAl2O4layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl2O4structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy Ki=1.22erg/cm2, which further increases to 1.30erg/cm2after annealing, while MgAl2O4/CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0nm, while that for top CoFeB layer is between 0.8 and 1.4nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl2O4/CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.

  5. Magnetic-plasmonic multilayered nanorods

    Science.gov (United States)

    Thumthan, Orathai

    Multilayered nanorods which consist of alternating magnetic layers separated by Au layers combine two distinctive properties, magnetic properties and surface plasmonic resonance (SPR) properties into one nano-entity. Their magnetic properties are tunable by changing the layer thickness, varying from single domain to superparamagnetic state. Superparamagnetic is a key requirement for magnetic nanoparticles for bioapplications. Superparamagnetic nanoparticles exhibit high magnetic moments at low applied magnetic field while retain no magnetic moments when magnetic field is removed preventing them from aggregation due to magnetic attraction. Au layers in the nanorods provide anchorage sites for functional group attachment. Also, Au nanodisks exhibit SPR properties. The SPR peak can be tuned from 540 nm to 820 nm by controlling the thickness of magnetic segments while keeping Au thickness constant. In this research, there are three types of multilayered nanorod have been fabricated: Au/NiFe nanorods, Au/Fe nanorods, and Au/Co nanorods. These magnetic nanorods were fabricated by templated electrodeposition into the channels in Anodic Aluminum Oxide (AAO) membrane. The setup for AAO fabrication was developed as a part of this research. Our fabricated AAO membrane has channels with a diameter ranging from 40nm to 80 nm and a thickness of 10um to 12um. Magnetic properties of nanorods such as saturation field, saturation moment, coercivity and remanence are able to manipulate through their shape anisotropy. The magnetization will be easier in long axis rather than short axis of particle. In addition, Au nanodisks in the nanorod structure are not only serving as anchorage sites for functional groups but also provide SPR properties. Under irradiation of light Au nanodisks strongly absorb light at SPR frequency which ranging from 540 nm to 820 nm by controlling the thickness of magnetic segments while keeping Au thickness constant. The SPR tunability of nanorods in near

  6. Degradation of periodic multilayers as seen by small-angle x-ray scattering and x-ray diffraction

    CERN Document Server

    Rafaja, D; Simek, D; Zdeborova, L; Valvoda, V

    2002-01-01

    The capabilities of small-angle x-ray scattering (SAXS) and wide-angle x-ray diffraction (XRD) to recognize structural changes in periodic multilayers were compared on Fe/Au multilayers with different degrees of structural degradation. Experimental results have shown that both methods are equally sensitive to the multilayer degradation, i.e., to the occurrence of non-continuous interfaces, to short-circuits in the multilayer structure and to the multilayer precipitation. XRD yielded additional information on the multilayer crystallinity, whilst SAXS could better recognize fragments of a long-range periodicity (remnants of the original multilayer structure). Changes in the multilayer structure were initiated by successive annealing at 200 and 300 deg. C. Experimental data were complemented by numerical simulations performed using a combination of optical theory and the distorted wave Born approximation for SAXS or the kinematical Born approximation for XRD.

  7. Extended asymmetric-cut multilayer X-ray gratings.

    Science.gov (United States)

    Prasciolu, Mauro; Haase, Anton; Scholze, Frank; Chapman, Henry N; Bajt, Saša

    2015-06-15

    The fabrication and characterization of a large-area high-dispersion blazed grating for soft X-rays based on an asymmetric-cut multilayer structure is reported. An asymmetric-cut multilayer structure acts as a perfect blazed grating of high efficiency that exhibits a single diffracted order, as described by dynamical diffraction throughout the depth of the layered structure. The maximum number of grating periods created by cutting a multilayer deposited on a flat substrate is equal to the number of layers deposited, which limits the size of the grating. The size limitation was overcome by depositing the multilayer onto a substrate which itself is a coarse blazed grating and then polish it flat to reveal the uniformly spaced layers of the multilayer. The number of deposited layers required is such that the multilayer thickness exceeds the step height of the substrate structure. The method is demonstrated by fabricating a 27,060 line pairs per mm blazed grating (36.95 nm period) that is repeated every 3,200 periods by the 120-μm period substrate structure. This preparation technique also relaxes the requirements on stress control and interface roughness of the multilayer film. The dispersion and efficiency of the grating is demonstrated for soft X-rays of 13.2 nm wavelength.

  8. Flow stress anisotropy

    DEFF Research Database (Denmark)

    Winther, G.

    1996-01-01

    stress Variation in the rolling plane, which may be as high as 20%, are presented. The traditional Taylor model is applied to the data to account for the effect of texture. However, texture effects alone are not enough to explain all of the observed anisotropy. New models which take the combined effects...... of texture and deformation microstructure into account are presented. The models are based on the Taylor and Sachs models but modified with an anisotropic critical shear stress to account for the effect of the microstructure. The agreement between experimental data and model predictions is definitely better...

  9. Automation Enhancement of Multilayer Laue Lenses

    Energy Technology Data Exchange (ETDEWEB)

    Lauer K. R.; Conley R.

    2010-12-01

    X-ray optics fabrication at Brookhaven National Laboratory has been facilitated by a new, state of the art magnetron sputtering physical deposition system. With its nine magnetron sputtering cathodes and substrate carrier that moves on a linear rail via a UHV brushless linear servo motor, the system is capable of accurately depositing the many thousands of layers necessary for multilayer Laue lenses. I have engineered a versatile and automated control program from scratch for the base system and many subsystems. Its main features include a custom scripting language, a fully customizable graphical user interface, wireless and remote control, and a terminal-based interface. This control system has already been successfully used in the creation of many types of x-ray optics, including several thousand layer multilayer Laue lenses.Before reaching the point at which a deposition can be run, stencil-like masks for the sputtering cathodes must be created to ensure the proper distribution of sputtered atoms. Quality of multilayer Laue lenses can also be difficult to measure, given the size of the thin film layers. I employ my knowledge of software and algorithms to further ease these previously painstaking processes with custom programs. Additionally, I will give an overview of an x-ray optic simulator package I helped develop during the summer of 2010. In the interest of keeping my software free and open, I have worked mostly with the multiplatform Python and the PyQt application framework, utilizing C and C++ where necessary.

  10. Controlling light with plasmonic multilayers

    DEFF Research Database (Denmark)

    Orlov, Alexey A.; Zhukovsky, Sergei; Iorsh, Ivan V.

    2014-01-01

    metamaterials and describe their use for light manipulation at the nanoscale. While demonstrating the recently emphasized hallmark effect of hyperbolic dispersion, we put special emphasis to the comparison between multilayered hyperbolic metamaterials and more broadly defined plasmonic-multilayer metamaterials...

  11. Magnetoresistant Co/Cu multilayers: effect of crystallographic orientation of the layers

    International Nuclear Information System (INIS)

    Boher, P.; Giron, F.; Houdy, P.; Beauvillain, P.; Chappert, C.; Veillet, P.

    1992-01-01

    In the last few years ferromagnetic/non-ferromagnetic multilayers have received considerable attention due to their great interest formagnetoresistive applications. Giant magnetoresistance has been observed in the Cu/Co system but with quite high saturation field (>>1 kOe). In this paper we report on an original way to enhance this characterisitc, using unusual fcc left angle 100 right angle cristallographic orientation. Special preparation of the right angle 100 right angle silicon substrates is investigated using in-situ kinetic ellipsometry, RHEED, grazing X-ray reflection and X-ray diffraction. We show that good quality fcc right angle 100 right angle pseudo-epitaxial copper surface can be obtained only when two conditions are fulfilled: first the silicon surface must be completely free of native oxide and second the copper buffer layer must be annealed under ultrahigh vacuum. Perfectly clean silicon surfaces are obtained by chemical etching followed by flash heating under ultrahigh vacuum. The copper buffer layer reacts with silicon and gives a textured fcc right angle 100 right angle Cu phase with a 45 rotation of the Cu left angle 100 right angle lattice with regards to the Si right angle 100 right angle one. Additional annealing leads to an homogencous interface silicide layer and improves the cristallinity of the Cu buffer layer. Cu/Co multilayers deposited on this kind of substrate show a well-defined fcc right angle 100 right angle texture for a large range of layer thickness. Oscillation of magnetoresistance with the copper thickness is observed with a period of about 10 A. The maximum of magnetoresistance is found for 20.9 A of Cu (ΔR/R∼6%), and the differential magnetoresistance is very high (ΔR/RΔH = 1.4 kOe -1 ). Combination of antiferromagnetic coupling and quadratic in-plane anisotropy of this special cristallographic orientation is responsible for this improvement. (orig.)

  12. Topographical Anisotropy and Wetting of Ground Stainless Steel Surfaces

    Directory of Open Access Journals (Sweden)

    Cornelia Bellmann

    2012-12-01

    Full Text Available Microscopic and physico-chemical methods were used for a comprehensive surface characterization of different mechanically modified stainless steel surfaces. The surfaces were analyzed using high-resolution confocal microscopy, resulting in detailed information about the topographic properties. In addition, static water contact angle measurements were carried out to characterize the surface heterogeneity of the samples. The effect of morphological anisotropy on water contact angle anisotropy was investigated. The correlation between topography and wetting was studied by means of a model of wetting proposed in the present work, that allows quantifying the air volume of the interface water drop-stainless steel surface.

  13. Symmetry mismatch-driven perpendicular magnetic anisotropy for perovskite/brownmillerite heterostructures.

    Science.gov (United States)

    Zhang, Jing; Zhong, Zhicheng; Guan, Xiangxiang; Shen, Xi; Zhang, Jine; Han, Furong; Zhang, Hui; Zhang, Hongrui; Yan, Xi; Zhang, Qinghua; Gu, Lin; Hu, Fengxia; Yu, Richeng; Shen, Baogen; Sun, Jirong

    2018-05-15

    Grouping different transition metal oxides together by interface engineering is an important route toward emergent phenomenon. While most of the previous works focused on the interface effects in perovskite/perovskite heterostructures, here we reported on a symmetry mismatch-driven spin reorientation toward perpendicular magnetic anisotropy in perovskite/brownmillerite heterostructures, which is scarcely seen in tensile perovskite/perovskite heterostructures. We show that alternately stacking perovskite La 2/3 Sr 1/3 MnO 3 and brownmillerite LaCoO 2.5 causes a strong interface reconstruction due to symmetry discontinuity at interface: neighboring MnO 6 octahedra and CoO 4 tetrahedra at the perovskite/brownmillerite interface cooperatively relax in a manner that is unavailable for perovskite/perovskite interface, leading to distinct orbital reconstructions and thus the perpendicular magnetic anisotropy. Moreover, the perpendicular magnetic anisotropy is robust, with an anisotropy constant two orders of magnitude greater than the in-plane anisotropy of the perovskite/perovskite interface. The present work demonstrates the great potential of symmetry engineering in designing artificial materials on demand.

  14. SnO2/PPy Screen-Printed Multilayer CO2 Gas Sensor

    Directory of Open Access Journals (Sweden)

    S.A. WAGHULEY

    2007-05-01

    Full Text Available Tin dioxide (SnO2 plays a dominant role in solid state gas sensors and exhibit sensitivity towards oxidizing and reducing gases by a variation of its electrical properties. The electrical conducting polymer-polypyrrole (PPy has high anisotropy of electrical conduction and used as a gas sensor. SnO2/PPy multilayer, pure SnO2, pure PPy sensors were prepared by screen-printing method on Al2O3 layer followed by glass substrate. The sensors were used for different concentration (ppm of CO2 gas investigation at room temperature (303 K. The sensitivity of SnO2/PPy multilayer sensor was found to be higher, compared with pure SnO2 and pure PPy sensors. The multilayer sensor exhibited improved stability. The response and recovery time of multilayer sensor were found to be ~2 min and ~10 min respectively.

  15. The characterization of multilayers analyzers: Models and measurements

    International Nuclear Information System (INIS)

    Henke, B.L.; Vejio, J.Y.; Tackaberry, R.E.; Yamada, H.T.

    1985-01-01

    A procedure is described for the detailed characterization of multilayer analyzers which can be effectively applied to their design, optimization and application for absolute x-ray spectrometry. An accurate analytical model has been developed that is based upon a simple modification of the dynamical Darwin-Prins theory to extend its application to finite multilayer systems. Its equivalence to the optical E and M solution of the Fresnel equations at each interface is demonstrated by detailed calculation comparisons for the reflectivity of a multilayer throughout the angular range of incidence of 0 to 90 0 . A special spectrograph and experimental method is described for the measurement of the absolute reflectivity characteristics of the multilayer. The experimental measurements at three photon energies in the 100-200 eV region are fit by the analytical modified Darwin-Prins equation (MDP) for I(θ), generating a detailed characterization of two ''state of the art'' multilayers, a sputtered tungsten-carbon of 2d ≅ 70 A and a molecular lead separate of 2d ≅ 100 A. The fitting parameters that are determined in this procedure are applied to help establish the structural characteristics of the particular multilayer

  16. Polymerization of vinyl stearate multilayers by electron beam irradiation

    International Nuclear Information System (INIS)

    Nishii, Masanobu; Hatada, Motoyoshi

    1975-01-01

    Studies on the radiation-induced polymerization of vinyl stearate (VST) multilayers were carried out. The VST multilayers built-up on an aluminum plated glass plate by Langmuir-Blodgett technique were irradiated with electron beams from a Van de Graaff electron accelerator in nitrogen atmosphere. The structure of the multilayers and the effects of irradiation were investigated by X-ray diffractometry, contact angle measurement, multireflection infrared spectroscopy, and scanning electron microscopy. The VST multilayers became insoluble to methanol by the irradiation, and the multi-reflection infrared spectrum of the VST multilayers turned into that of poly (VST) with increasing dosage. The polymerization proceeded during the irradiation at the temperature range between -10 0 and 10 0 C, and the conversion attained to 90% within 2.5 minutes (total dose, 5.6 Mrads). The multilayers irradiated above 13 Mrads turned into the polymer film insoluble to benzene, indicating that the polymer chains were cross-linked by the irradiation. Stearic acid which was formed by the irradiation of VST at nitrogen-water interface as a hydrolysis product was not detected in this system. (auth.)

  17. Evolution of topological skyrmions across the spin reorientation transition in Pt/Co/Ta multilayers

    Science.gov (United States)

    He, Min; Li, Gang; Zhu, Zhaozhao; Zhang, Ying; Peng, Licong; Li, Rui; Li, Jianqi; Wei, Hongxiang; Zhao, Tongyun; Zhang, X.-G.; Wang, Shouguo; Lin, Shi-Zeng; Gu, Lin; Yu, Guoqiang; Cai, J. W.; Shen, Bao-gen

    2018-05-01

    Magnetic skyrmions in multilayers are particularly appealing as next generation memory devices due to their topological compact size, the robustness against external perturbations, the capability of electrical driving and detection, and the compatibility with the existing spintronic technologies. To date, Néel-type skyrmions at room temperature (RT) have been studied mostly in multilayers with easy-axis magnetic anisotropy. Here, we systematically broadened the evolution of magnetic skyrmions with sub-50-nm size in a series of Pt/Co/Ta multilayers where the magnetic anisotropy is tuned continuously from easy axis to easy plane by increasing the ferromagnetic Co layer thickness. The existence of nontrivial skyrmions is identified via the combination of in situ Lorentz transmission electron microscopy (L-TEM) and Hall transport measurements. A high density of magnetic skyrmions over a wide temperature range is observed in the multilayers with easy-plane anisotropy, which will stimulate further exploration for new materials and accelerate the development of skyrmion-based spintronic devices.

  18. Nano-sized Adsorbate Structure Formation in Anisotropic Multilayer System

    Science.gov (United States)

    Kharchenko, Vasyl O.; Kharchenko, Dmitrii O.; Yanovsky, Vladimir V.

    2017-05-01

    In this article, we study dynamics of adsorbate island formation in a model plasma-condensate system numerically. We derive the generalized reaction-diffusion model for adsorptive multilayer system by taking into account anisotropy in transfer of adatoms between neighbor layers induced by electric field. It will be found that with an increase in the electric field strength, a structural transformation from nano-holes inside adsorbate matrix toward separated nano-sized adsorbate islands on a substrate is realized. Dynamics of adsorbate island sizes and corresponding distributions are analyzed in detail. This study provides an insight into details of self-organization of adatoms into nano-sized adsorbate islands in anisotropic multilayer plasma-condensate systems.

  19. Preferential orientation of magnetization and interfacial disorder in Co/Au multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Quispe-Marcatoma, J., E-mail: justinianoqm@gmail.com [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, P.O. Box 14–0149, Lima 14, Perú (Peru); Pandey, B. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Alayo, W. [Departamento de Física, Universidade Federal de Pelotas, Campus Universitário, 96010-900 Pelotas, RS (Brazil); Sousa, M.A. de; Pelegrini, F. [Instituto de Física, Universidade Federal de Goiás, Goiânia 74001-970 (Brazil); Saitovitch, E. Baggio [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil)

    2013-10-15

    Two families of Co/Au multilayer films with different interlayer magnetostatic coupling were grown by the DC magnetron sputtering technique. The structure of these films was analyzed by X-ray diffraction (XRD), and the magnetic properties by vibrating sample magnetometer (VSM) and ferromagnetic resonance (FMR) spectroscopy. All these techniques give complementary information about the structure of the multilayers and the magnetization direction as a function of thickness of the Co layers. The structural analysis shows a decrease of the interfacial disorder for increasing Co layer thickness in both groups of samples. This behavior has been correlated with a transition of the magnetization direction from perpendicular to parallel to the films plane. Thin Co layer samples gave high remnant magnetization with very low saturation field while thick Co layer samples showed low remnant magnetization with high value of saturation field. In the FMR study, the spectra showed two resonance modes, which were associated to the internal and interfacial Co atoms. Volume (K{sub v}) and surface (K{sub s}) anisotropy constants were deduced from the FMR experiments and are in good agreement with the reported values for Co/Au multilayers. - Highlights: • We find a competition between the magnetostatic coupling and magnetic anisotropy. • We find two resonant modes associated to different environments of Co atoms. • The main mode shows perpendicular magnetic anisotropy for samples with t{sub Co}<10 Å. • The secondary mode shows in-plane anisotropy for samples with t{sub Co}<10 Å.

  20. Magnetic studies in evaporated Ni/Pd multilayers

    International Nuclear Information System (INIS)

    Chafai, K.; Salhi, H.; Lassri, H.; Yamkane, Z.; Lassri, M.; Abid, M.; Hlil, E.K.; Krishnan, R.

    2011-01-01

    The magnetic properties of Ni/Pd multilayers, prepared by sequential evaporation in ultrahigh vacuum, have been studied. The Ni thickness dependence of the magnetization and magnetic anisotropy is discussed. The temperature dependence of the spontaneous magnetization is well described by a T 3/2 law in all multilayers. A spin-wave theory has been used to explain the temperature dependence of the spontaneous magnetization, and the approximate values for the exchange interactions for various Ni layer thicknesses have been obtained. - Research highlights: → The magnetic properties of Ni/Pd multilayers, prepared by sequential evaporation in ultrahigh vacuum, have been studied. → The temperature dependence of the spontaneous magnetization is well described by a T 3/2 law in Ni/Pd multilayers. → The spin-wave constant B was observed to depend on t Ni nonmonotonically. → A spin-wave theory has been used to explain the temperature dependence of the spontaneous magnetization. → The approximate values for the exchange interactions for various Ni layer thicknesses have been obtained.

  1. Effects of Co layer thickness and annealing temperature on the magnetic properties of inverted [Pt/Co] multilayers

    International Nuclear Information System (INIS)

    Lee, Tae Young; Chan Won, Young; Su Son, Dong; Lee, Seong-Rae; Ho Lim, Sang

    2013-01-01

    The effects of Co layer thickness and annealing temperature on the perpendicular magnetic anisotropy (PMA) properties of inverted [Pt (0.2 nm)/Co (t Co )] 6 multilayers (where t Co indicates the thickness of the Co layer) have been investigated. The cross-sectional microstructure, as observed from the high-resolution transmission electron microscope images, shows a clear layered structure with atomically flat interfaces both in the as-deposited state as well as after annealing, indicating the interface effects for PMA. The effective PMA energy density (K eff ) increases significantly with an increase in t Co from 0.2 to 0.28 nm and then becomes almost saturated with further increases in t Co , followed by a slight reduction at the highest Co thickness, t Co  = 0.6 nm. In order to explain the t Co dependence on K eff , the intrinsic PMA energy density (K i ) is calculated by additionally measuring a similar set of results for the saturation magnetization. The K i value increases nearly linearly with the increase in t Co from 0.2 to 0.5 nm, followed by saturation at a higher t Co value of 0.6 nm. Owing to a close relationship between K i and the quality of the interfaces, these results indicate a similar t Co dependence on the quality of the interfaces. This is further supported from the magnetic measurements of the samples annealed at the highest temperature of 500 °C, where a second phase is formed, which show a similar t Co dependence on the amount of the second phase. The K i value is nearly independent of the annealing temperature at t Co  ≤ 0.4 nm, above which a substantial reduction is observed, when the annealing temperature exceeds 500 °C

  2. Consequences of elastic anisotropy in patterned substrate heteroepitaxy.

    Science.gov (United States)

    Dixit, Gopal Krishna; Ranganathan, Madhav

    2018-06-13

    The role of elastic anisotropy on quantum dot formation and evolution on a pre-patterned substrate is evaluated within the framework of a continuum model. We first extend the formulation for surface evolution to take elastic anisotropy into account. Using a small slope approximation, we derive the evolution equation and show how it can be numerically implemented up to linear and second order for stripe and egg-carton patterned substrates using an accurate and efficient procedure. The semi--infinite nature of the substrate is used to solve the elasticity problem subject to other boundary conditions at the free surface and at the film--substrate interface. The positioning of the quantum dots with respect to the peaks and valleys of the pattern is explained by a competition between the length scale of the pattern and the wavelength of the Asaro--Tiller--Grinfeld instability, which is also affected by the elastic anisotropy. The alignment of dots is affected by a competition between the elastic anisotropy of the film and the pattern orientation. A domain of pattern inversion, wherein the quantum dots form exclusively in the valleys of the patterns is identified as a function of the average film thickness and the elastic anisotropy, and the time--scale for this inversion as function of height is analyzed. © 2018 IOP Publishing Ltd.

  3. Role of the magnetic anisotropy in organic spin valves

    Directory of Open Access Journals (Sweden)

    V. Kalappattil

    2017-09-01

    Full Text Available Magnetic anisotropy plays an important role in determining the magnetic functionality of thin film based electronic devices. We present here, the first systematic study of the correlation between magnetoresistance (MR response in organic spin valves (OSVs and magnetic anisotropy of the bottom ferromagnetic electrode over a wide temperature range (10 K–350 K. The magnetic anisotropy of a La0.67Sr0.33MnO3 (LSMO film epitaxially grown on a SrTiO3 (STO substrate was manipulated by reducing film thickness from 200 nm to 20 nm. Substrate-induced compressive strain was shown to drastically increase the bulk in-plane magnetic anisotropy when the LSMO became thinner. In contrast, the MR response of LSMO/OSC/Co OSVs for many organic semiconductors (OSCs does not depend on either the in-plane magnetic anisotropy of the LSMO electrodes or their bulk magnetization. All the studied OSV devices show a similar temperature dependence of MR, indicating a similar temperature-dependent spinterface effect irrespective of LSMO thickness, resulting from the orbital hybridization of carriers at the OSC/LSMO interface.

  4. High spin-polarization in ultrathin Co2MnSi/CoPd multilayers

    Science.gov (United States)

    Galanakis, I.

    2015-03-01

    Half-metallic Co2MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co2MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co2MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices.

  5. Dependence of Magnetic Properties of Co/Pt Multilayers on Deposition Temperature of Pt Buffer Layers

    Science.gov (United States)

    Shiomi, Shigeru; Nishimura, Tomotaka; Kobayashi, Tadashi; Masuda, Morio

    1993-04-01

    A 15-nm-thick Pt buffer layer was deposited on a glass slide at temperature Ts(Ptbuf) ranging from 30 to 300°C by e-gun evaporation. Following the cooling in vacuum to ambient temperature, Co and Pt layers have been alternately deposited on it. Very large perpendicular anisotropy and coercivity have been obtained at Ts(Ptbuf) higher than 200°C. The (111) preferred orientation of the Co/Pt multilayer as well as the Pt buffer layer became more pronounced with elevating Ts(Ptbuf), to which the enhancement of perpendicular anisotropy with elevating Ts(Ptbuf) might be ascribable.

  6. Thickness and angular dependent magnetic anisotropy of La0.67Sr0.33MnO3 thin films by Vectorial Magneto Optical Kerr Magnetometry

    Science.gov (United States)

    Chaluvadi, S. K.; Perna, P.; Ajejas, F.; Camarero, J.; Pautrat, A.; Flament, S.; Méchin, L.

    2017-10-01

    We investigate the in-plane magnetic anisotropy in La0.67Sr0.33MnO3 thin films grown on SrTiO3 (001) substrate using angular dependent room temperature Vectorial Magneto-Optical Kerr Magnetometry. The experimental data reveals that the magnetic anisotropy symmetry landscape significantly changes depending upon the strain and thickness. At low film thickness (12 and 25 nm) the dominant uniaxial anisotropy is due to interface effects, step edges due to mis-cut angle of SrTiO3 substrate. At intermediate thickness, the magnetic anisotropy presents a competition between magnetocrystalline (biaxial) and substrate step induced (uniaxial) anisotropy. Depending upon their relative strengths, a profound biaxial or uniaxial or mixed anisotropy is favoured. Above the critical thickness, magnetocrystalline anisotropy dominates all other effects and shows a biaxial anisotropy.

  7. Digital multilayer tomography

    International Nuclear Information System (INIS)

    Dueber, C.; Klose, K.J.; Thelen, M.

    1991-01-01

    With digital multilayer tomography a sequence of projection images is recorded by an image intensifier television system and stored as digital data during a linear run of a layer sequence. Using this data record, tomograms of the examined body region can be computed for any layer thickness by shifts and superimposition of the single projections later at a digital workstation. The qualities of digital and conventional tomograms are basically comparable. A drawback of digital tomography is its lower local resolution (512 x 512 image matrix), advantages are a lower radiation exposure, a shorter patient examination time, and the facilities of digital image processing (later processing, archive setup, transmission). (orig.) [de

  8. Interfacial behaviour of biopolymer multilayers

    NARCIS (Netherlands)

    Corstens, Meinou N.; Osorio Caltenco, Lilia A.; Vries, de Renko; Schroën, Karin; Berton-Carabin, Claire C.

    2017-01-01

    Although multilayered emulsions have been related to reduced lipolysis, the involved interfacial phenomena have never been studied directly. In this work, we systematically built multilayers of whey protein and pectin, which we further subjected to digestive conditions, using two different

  9. Compositionally Graded Multilayer Ceramic Capacitors.

    Science.gov (United States)

    Song, Hyun-Cheol; Zhou, Jie E; Maurya, Deepam; Yan, Yongke; Wang, Yu U; Priya, Shashank

    2017-09-27

    Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. Here, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (filters and power converters.

  10. Anisotropy in the deep Earth

    Science.gov (United States)

    Romanowicz, Barbara; Wenk, Hans-Rudolf

    2017-08-01

    Seismic anisotropy has been found in many regions of the Earth's interior. Its presence in the Earth's crust has been known since the 19th century, and is due in part to the alignment of anisotropic crystals in rocks, and in part to patterns in the distribution of fractures and pores. In the upper mantle, seismic anisotropy was discovered 50 years ago, and can be attributed for the most part, to the alignment of intrinsically anisotropic olivine crystals during large scale deformation associated with convection. There is some indication for anisotropy in the transition zone, particularly in the vicinity of subducted slabs. Here we focus on the deep Earth - the lower mantle and core, where anisotropy is not yet mapped in detail, nor is there consensus on its origin. Most of the lower mantle appears largely isotropic, except in the last 200-300 km, in the D″ region, where evidence for seismic anisotropy has been accumulating since the late 1980s, mostly from shear wave splitting measurements. Recently, a picture has been emerging, where strong anisotropy is associated with high shear velocities at the edges of the large low shear velocity provinces (LLSVPs) in the central Pacific and under Africa. These observations are consistent with being due to the presence of highly anisotropic MgSiO3 post-perovskite crystals, aligned during the deformation of slabs impinging on the core-mantle boundary, and upwelling flow within the LLSVPs. We also discuss mineral physics aspects such as ultrahigh pressure deformation experiments, first principles calculations to obtain information about elastic properties, and derivation of dislocation activity based on bonding characteristics. Polycrystal plasticity simulations can predict anisotropy but models are still highly idealized and neglect the complex microstructure of polyphase aggregates with strong and weak components. A promising direction for future progress in understanding the origin of seismic anisotropy in the deep mantle

  11. Surface energy anisotropy of tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R; Grenga, H E [Georgia Inst. of Tech., Atlanta (USA). School of Chemical Engineering

    1976-10-01

    Field-ion microscopy was used to study the faceting behavior and/or surface energy anisotropy of tungsten in vacuum and in hydrogen. In vacuum below 1700 K the activation energy for (110) facet growth agreed with values previously reported for surface diffusion on tungsten. The observed anisotropy values at 0.5 Tsub(m), where Tsub(m) is the absolute melting temperature of tungsten (approximately 3680 K), were different from those previously reported at higher temperatures and more nearly agreed with broken bond calculations based on Mie potential using m=5, n=8, and a 1.5% lattice expansion. Hydrogen appeared to have a negligible effect on surface energy anisotropy, but did preferentially increase surface diffusion rates on (310) regions.

  12. High temperature interface superconductivity

    International Nuclear Information System (INIS)

    Gozar, A.; Bozovic, I.

    2016-01-01

    Highlight: • This review article covers the topic of high temperature interface superconductivity. • New materials and techniques used for achieving interface superconductivity are discussed. • We emphasize the role played by the differences in structure and electronic properties at the interface with respect to the bulk of the constituents. - Abstract: High-T_c superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T_c Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  13. Hot-rolled Process of Multilayered Composite Metal Plate

    Directory of Open Access Journals (Sweden)

    YU Wei

    2017-02-01

    Full Text Available For multi-layer plate, it is a difficult problem to increase product yield rate and improve bonding interface quality. A high yield hot-rolled method of multilayered plate was proposed. The raw strips and plate were fixed by argon arc welding. The combined billet was put into a metal box and vacuum pumped, and then heated and rolled by multi passes at the temperature of 1000-1200℃. The 67 layered plate with the thickness of 2.5mm was successfully produced. The interfacial microstructures and diffusion behavior were investigated and analyzed by optical microscopy and scan electronic microscopy. The tensile and shear strength were tested,and the shear fractures were analyzed. The results show that the multilayered plate yield rate is more than 90% by two steps billet combination method and rolling process optimization. The good bonding interface quality is obtained, the shear strength of multilayered plate reaches 241 MPa. Nickel interlayer between 9Cr18 and 1Cr17 can not only prevent the diffusion of carbon, but also improve the microstructure characteristics.

  14. Ultrahard Multilayer Coatings

    International Nuclear Information System (INIS)

    Chrzan, D.C.; Dugger, M.; Follstaedt, D.M.; Friedman, Lawrence H.; Friedmann, T.A.; Knapp, J.A.; McCarty, K.F.; Medlin, D.L.; Mirkarimi, P.B.; Missert, N.; Newcomer, P.P.; Sullivan, J.P.; Tallant, D.R.

    1999-01-01

    We have developed a new multilayer a-tC material that is thick stress-free, adherent, low friction, and with hardness and stiffness near that of diamond. The new a-tC material is deposited by J pulsed-laser deposition (PLD) at room temperature, and fully stress-relieved by a short thermal anneal at 600 ampersand deg;C. A thick multilayer is built up by repeated deposition and annealing steps. We measured 88 GPa hardness, 1100 GPa Young's modulus, and 0.1 friction coefficient (under high load). Significantly, these results are all well within the range reported for crystalline diamond. In fact, this material, if considered separate from crystalline diamond, is the 2nd hardest material known to man. Stress-free a-tC also has important advantages over thin film diamond; namely, it is smooth, processed at lower temperature, and can be grown on a much broader range of substrates. This breakthrough will enable a host of applications that we are actively pursuing in MEMs, sensors, LIGA, etc

  15. Wrapped Multilayer Insulation

    Science.gov (United States)

    Dye, Scott A.

    2015-01-01

    New NASA vehicles, such as Earth Departure Stage (EDS), Orion, landers, and orbiting fuel depots, need improved cryogenic propellant transfer and storage for long-duration missions. Current cryogen feed line multilayer insulation (MLI) performance is 10 times worse per area than tank MLI insulation. During each launch, cryogenic piping loses approximately 150,000 gallons (equivalent to $300,000) in boil-off during transfer, chill down, and ground hold. Quest Product Development Corp., teaming with Ball Aerospace, developed an innovative advanced insulation system, Wrapped MLI (wMLI), to provide improved thermal insulation for cryogenic feed lines. wMLI is high-performance multilayer insulation designed for cryogenic piping. It uses Quest's innovative discrete-spacer technology to control layer spacing/ density and reduce heat leak. The Phase I project successfully designed, built, and tested a wMLI prototype with a measured heat leak 3.6X lower than spiral-wrapped conventional MLI widely used for piping insulation. A wMLI prototype had a heat leak of 7.3 W/m2, or 27 percent of the heat leak of conventional MLI (26.7 W/m2). The Phase II project is further developing wMLI technology with custom, molded polymer spacers and advancing the product toward commercialization via a rigorous testing program, including developing advanced vacuuminsulated pipe for ground support equipment.

  16. Momentum anisotropy at freeze out

    International Nuclear Information System (INIS)

    Feld, S.; Borghini, N.; Lang, C.

    2017-01-01

    The transition from a hydrodynamical modeling to a particle-based approach is a crucial element of the description of high-energy heavy-ion collisions. Assuming this “freeze out” happens instantaneously at each point of the expanding medium, we show that the local phase-space distribution of the emitted particles is asymmetric in momentum space. This suggests the use of anisotropic hydrodynamics for the last stages of the fluid evolution. We discuss how observables depend on the amount of momentum-space anisotropy at freeze out and how smaller or larger anisotropies allow for different values of the freeze-out temperature. (paper)

  17. Study of domain wall propagation in nanostructured CoPt multilayers by using antisymmetric magnetoresistance

    International Nuclear Information System (INIS)

    Rodriguez-Rodriguez, G; Perez-Junquera, A; Hierro-Rodriguez, A; Montenegro, N; Alameda, J M; Velez, M; Menendez, J L; Ravelosona, D

    2010-01-01

    Domain wall propagation has been studied in perpendicular anisotropy CoPt multilayers patterned by e-beam lithography into 5 μm wide wires. Positive and negative peaks appear in time resolved magnetoresistance curves, associated to the different directions of domain wall propagation along the wires. The field dependence of domain wall velocity is well described by a creep model of a 1D wall in the presence of weak disorder with critical exponent μ=1/4.

  18. The effect of polymer charge density and charge distribution on the formation of multilayers

    CERN Document Server

    Voigt, U; Tauer, K; Hahn, M; Jäger, W; Klitzing, K V

    2003-01-01

    Polyelectrolyte multilayers which are built up by alternating adsorption of polyanions and polycations from aqueous solutions at a solid interface are investigated by reflectometry and ellipsometry. Below a degree of charge of about 70% the adsorption stops after a certain number of dipping cycles and no multilayer formation occurs. This indicates an electrostatically driven adsorption process. Below a charge density of 70% an adsorption can take place if the charged segments are combined as a block of the polymer.

  19. Nanostructure multilayer dielectric materials for capacitors and insulators

    Science.gov (United States)

    Barbee, Jr., Troy W.; Johnson, Gary W.

    1998-04-21

    A capacitor is formed of at least two metal conductors having a multilayer dielectric and opposite dielectric-conductor interface layers in between. The multilayer dielectric includes many alternating layers of amorphous zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3). The dielectric-conductor interface layers are engineered for increased voltage breakdown and extended service life. The local interfacial work function is increased to reduce charge injection and thus increase breakdown voltage. Proper material choices can prevent electrochemical reactions and diffusion between the conductor and dielectric. Physical vapor deposition is used to deposit the zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3) in alternating layers to form a nano-laminate.

  20. Mechanism of tailored magnetic anisotropy in amorphous Co{sub 68}Fe{sub 24}Zr{sub 8} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Yu, E-mail: yu.fu@uni-due.de, E-mail: cangcangzhulin@gmail.com; Meckenstock, R.; Farle, M. [Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universität Duisburg-Essen, 47057 Duisburg (Germany); Barsukov, I., E-mail: ibarsuko@uci.edu [Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universität Duisburg-Essen, 47057 Duisburg (Germany); Physics and Astronomy, University of California, Irvine, California 92697 (United States); Lindner, J. [Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universität Duisburg-Essen, 47057 Duisburg (Germany); Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstr. 400, 01328 Dresden (Germany); Raanaei, H. [Department of Physics, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Hjörvarsson, B. [Department of Physics and Astronomy, Uppsala University, Box 516 SE-75120 Uppsala (Sweden)

    2014-02-17

    The mechanism of tailored magnetic anisotropy in amorphous Co{sub 68}Fe{sub 24}Zr{sub 8} thin films was investigated by ferromagnetic resonance (FMR) on samples deposited without an applied magnetic field, with an out-of-plane field and an in-plane field. Analysis of FMR spectra profiles, high frequency susceptibility calculations, and statistical simulations using a distribution of local uniaxial magnetic anisotropy reveal the presence of atomic configurations with local uniaxial anisotropy, of which the direction can be tailored while the magnitude remains at an intrinsically constant value of 3.0(2) kJ/m{sup 3}. The in-plane growth field remarkably sharpens the anisotropy distribution and increases the sample homogeneity. The results benefit designing multilayer spintronic devices based on highly homogeneous amorphous layers with tailored magnetic anisotropy.

  1. Some device implications of voltage controlled magnetic anisotropy in Co/Gd2O3 thin films through REDOX chemistry

    Science.gov (United States)

    Hao, Guanhua; Noviasky, Nicholas; Cao, Shi; Sabirianov, Ildar; Yin, Yuewei; Ilie, Carolina C.; Kirianov, Eugene; Sharma, Nishtha; Sokolov, Andrei; Marshall, Andrew; Xu, Xiaoshan; Dowben, Peter A.

    2018-04-01

    The effect of intermediate interfacial oxidation on the in-plane magnetization of multilayer stack Pt/Co/Gd2O3, on a p-type silicon substrate, has been investigated by magneto-optical Kerr effect (MOKE) measurements, the anomalous Hall effect, and magnetoresistance measurements. While voltage controlled perpendicular magnetic anisotropy of a metal/oxide heterostructure is known, this heterostructure displays an inverse relationship between voltage and coercivity. The anomalous Hall effect demonstrates a significant change in hysteresis, with the applied bias sign. There is a higher perpendicular magnetic anisotropy with positive bias exposure.

  2. Preferential growth in FeCoV/Ti:N multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, D.; Senthil Kumar, M.; Boeni, P.; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    The preferential growth in Fe{sub 0.50}Co{sub 0.48}V{sub 0.02}/Ti:N multilayers was studied by X-ray diffraction. X-ray specular reflectometry and subsequent simulation of the spectra was used to extract information about the thickness and interface roughness of individual layers. The investigation gives structural information about the material combination and its potential for the use of neutron polarizers. (author) 2 figs., 1 tab., 2 refs.

  3. Modeling release of chemicals from multilayer materials into food

    Directory of Open Access Journals (Sweden)

    Huang Xiu-Ling

    2016-01-01

    Full Text Available The migration of chemicals from materials into food is predictable by various mathematical models. In this article, a general mathematical model is developed to quantify the release of chemicals through multilayer packaging films based on Fick's diffusion. The model is solved numerically to elucidate the effects of different diffusivity values of different layers, distribution of chemical between two adjacent layers and between material and food, mass transfer at the interface of material and food on the migration process.

  4. Flow stress anisotropy in aluminium

    DEFF Research Database (Denmark)

    Juul Jensen, D.; Hansen, N.

    1990-01-01

    The plastic anisotropy of cold-rolled high purity aluminum (99.996%) and commercially pure aluminum (99.6%) has been investigated. Sample parameters were the initial grain size and the degree of plastic strain (ϵ < 3.00). Flow stresses (0.2% offset) were measured at room temperature by uniaxial t...

  5. The Cosmic Microwave Background Anisotropy

    Science.gov (United States)

    Bennett, C. L.

    1994-12-01

    The properties of the cosmic microwave background radiation provide unique constraints on the history and evolution of the universe. The first detection of anisotropy of the microwave radiation was reported by the COBE Team in 1992, based on the first year of flight data. The latest analyses of the first two years of COBE data are reviewed in this talk, including the amplitude of the microwave anisotropy as a function of angular scale and the statistical nature of the fluctuations. The two-year results are generally consistent with the earlier first year results, but the additional data allow for a better determination of the key cosmological parameters. In this talk the COBE results are compared with other observational anisotropy results and directions for future cosmic microwave anisotropy observations will be discussed. The National Aeronautics and Space Administration/Goddard Space Flight Center (NASA/GSFC) is responsible for the design, development, and operation of the Cosmic Background Explorer (COBE). Scientific guidance is provided by the COBE Science Working Group.

  6. Neutron optics with multilayer monochromators

    International Nuclear Information System (INIS)

    Saxena, A.M.; Majkrzak, C.F.

    1984-01-01

    A multilayer monochromator is made by depositing thin films of two materials in an alternating sequence on a glass substrate. This makes a multilayer periodic in a direction perpendicular to the plane of the films, with a d-spacing equal to the thickness of one bilayer. Neutrons of wavelength λ incident on a multilayer will be reflected at an angle phi given by the Bragg relation nλ = 2d sinphi, where n is the order of reflection. The use of thin-film multilayers for monochromating neutrons is discussed. Because of the low flux of neutrons, the samples have to be large, and the width of the incident beam can be as much as 2 cm. Multilayers made earlier were fabricated by resistive heating of the materials in a vacuum chamber. Because of geometrical constraints imposed by the size of the vacuum chamber, limits on the amount of material that can be loaded in a boat, and finite life of the boats, this method of preparation limits the length of a multilayer to ∼ 15 cm and the total number of bilayers in a multilayer to about 200. This paper discusses a thin-film deposition system using RF sputtering for depositing films

  7. Surface alignment of liquid crystal multilayers evaporated on a photoaligned polyimide film observed by surface profiler

    International Nuclear Information System (INIS)

    Oo, T.N.; Iwata, T.; Kimura, M.; Akahane, T.

    2005-01-01

    The investigation of the surface alignment of liquid crystal (LC) multilayers evaporated on a photoaligned polyimide vertical alignment (PI-VA) film was carried out by means of a novel three-dimensional (3-D) surface profiler. The photoinduced anisotropy of the partially UV-exposed PI-VA film can be visualized as a topological image of LC multilayers. It seems that the topology of LC multilayers is indicating the orientational distribution of LC molecules on the treated film. Moreover, it was shown that the surface profiler can be used to produce non-contact images with high vertical resolution (∼ 0.01 nm). Copyright (2003) AD-TECH - International Foundation for the Advancement of Technology Ltd

  8. High spin-polarization in ultrathin Co{sub 2}MnSi/CoPd multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Galanakis, I., E-mail: galanakis@upatras.gr

    2015-03-01

    Half-metallic Co{sub 2}MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co{sub 2}MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co{sub 2}MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices. - Highlights: • Ab-initio study of ultrathin Co{sub 2}MnSi/CoPd multilayers. • Large values of spin-polarization at the Fermi are retained. • Route for novel spintronic/magnetoelectronic devices.

  9. High spin-polarization in ultrathin Co2MnSi/CoPd multilayers

    International Nuclear Information System (INIS)

    Galanakis, I.

    2015-01-01

    Half-metallic Co 2 MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co 2 MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co 2 MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices. - Highlights: • Ab-initio study of ultrathin Co 2 MnSi/CoPd multilayers. • Large values of spin-polarization at the Fermi are retained. • Route for novel spintronic/magnetoelectronic devices

  10. Multilayer optics for x-ray analysis: design - fabrication - application

    International Nuclear Information System (INIS)

    Dietsch, R.; Holz, Th.; Bruegemann, L.

    2002-01-01

    Full text: The use of multilayer optics induced a decisive extension of opportunities in laboratory based X-ray analysis. With the growing number of different applications, more and more dedicated X-ray optics are required, optimized for the spectral range they are intended to be used for. Both the characteristic of the used X-ray source and the design of the multilayer optics finally define the performance of the conditioned incident beam for the application. In any case, qualified spacer and absorber materials have to be selected for the deposition of the multilayer in respect to the designated X-ray wavelength. X-ray optical devices based on uniform multilayers have the advantage of a wide acceptance angle but show chromatic aberrations. This effect can be avoided by synthesizing a multilayer with a lateral thickness gradient. The gradient ensures that any beam of a certain wavelength emitted from an infinite narrow X-ray source impinging the multilayer optics fulfills the Bragg condition. Three different types of curvature of laterally graded multilayer mirrors are used for X-ray analysis experiments: parabolic, elliptic and planar, which result in parallel, focusing and divergent beam conditions, respectively. Furthermore, the X-ray beam characteristics: intensity, monochromasy, divergence, beam width and brilliance can be additionally conditioned by combining one multilayer optics with either a different optic and/or with a crystal monochromator. The deposition of nanometer-multilayers, used as X-ray optical components, result in extraordinary requirements of the deposition process concerning precision, reproducibility and long term stability. Across a stack of more than 150 individual layers with thicknesses in the range between 1 to 10 nm, a variation of single layer thickness considerably lower than σ D = 0.1 nm and an interface roughness below σ R = 0.25 nm have to be achieved. Thickness homogeneity Δd/d -8 have to be guaranteed across macroscopic

  11. Exploring the magnetization dynamics of NiFe/Pt multilayers in flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Corrêa, M.A., E-mail: marciocorrea@dfte.ufrn.br [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Dutra, R.; Marcondes, T.L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil); Mori, T.J.A. [Laboratório Nacional de Luz Síncrotron, Rua Giuseppe Máximo Scolfaro, 1000, Guará, 13083-100 Campinas, SP (Brazil); Bohn, F. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Sommer, R.L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil)

    2016-09-15

    Highlights: • Magnetic properties of multilayers grown onto flexible substrates were investigated. • Experimental and theoretical magnetization dynamics results are presented. • The flexible substrates become promising candidate for rf-frequency devices. - Abstract: We investigate the structural and magnetic properties, and the magnetization dynamics in Ni{sub 81}Fe{sub 19}/Pt multilayer systems grown onto rigid and flexible substrates. The structural characterization shows evidence of a superlattice behavior, while the quasi-static magnetization characterization reveal a weak magnetic anisotropy induced in the multilayers. The magnetization dynamics is investigated through the magnetoimpedance effect. We employ a theoretical approach to describe the experimental magnetoimpedance effect and verify the influence of the effective damping parameter on the magnetization dynamics. Experimental data and theoretical results are in agreement and suggest that the multilayers present high effective damping parameter. Moreover, our experiments raise an interesting issue on the possibility of achieving considerable MI% values, even for systems with weak magnetic anisotropy and high damping parameter grown onto flexible substrates.

  12. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  13. Dipole radiation in a multilayer geometry

    International Nuclear Information System (INIS)

    Reed, C.E.; Giergiel, J.; Hemminger, J.C.; Ushioda, S.

    1987-01-01

    There are several kinds of experiments that can be done with multilayer stacks of dielectric media which require an understanding of light emission by sources within the stack for their analysis. These experiments may involve, for example, light-emitting tunnel junctions, Raman scattering in Kretschmann and other multilayered geometries, and Rayleigh scattering by small amounts of surface or interface roughness, either alone or in combination with other processes. A set of electromagnetic Green's functions for a multilayer stack of isotropic dielectric media [D. L. Mills and A. A. Maradudin, Phys. Rev. B 12, 2943 (1975)] gives the electric fields produced everywhere by a point source of current oscillating at a frequency f. These Green's functions can thus be used to solve this type of problem. In this paper we show how these Green's functions can be written in terms of 2 x 2 transfer matrices of the type commonly used to find the fields in a dielectric stack due to an incident plane wave. With this simplification we can easily evaluate the Green's functions for a stack with an arbitrary number of layers. We further show that, when the electric fields generated by a point source within the stack are evaluated far away, they can be written directly in terms of the electric fields that would be generated at the location of the current source by plane waves incident from the direction of the observation point. We show that this follows from the Lorentz reciprocity theorem. Thus, in this case the formalism of Green's functions is not needed

  14. Integrated Multilayer Insulation

    Science.gov (United States)

    Dye, Scott

    2009-01-01

    Integrated multilayer insulation (IMLI) is being developed as an improved alternative to conventional multilayer insulation (MLI), which is more than 50 years old. A typical conventional MLI blanket comprises between 10 and 120 metallized polymer films separated by polyester nets. MLI is the best thermal- insulation material for use in a vacuum, and is the insulation material of choice for spacecraft and cryogenic systems. However, conventional MLI has several disadvantages: It is difficult or impossible to maintain the desired value of gap distance between the film layers (and consequently, it is difficult or impossible to ensure consistent performance), and fabrication and installation are labor-intensive and difficult. The development of IMLI is intended to overcome these disadvantages to some extent and to offer some additional advantages over conventional MLI. The main difference between IMLI and conventional MLI lies in the method of maintaining the gaps between the film layers. In IMLI, the film layers are separated by what its developers call a micro-molded discrete matrix, which can be loosely characterized as consisting of arrays of highly engineered, small, lightweight, polymer (typically, thermoplastic) frames attached to, and placed between, the film layers. The term "micro-molded" refers to both the smallness of the frames and the fact that they are fabricated in a process that forms precise small features, described below, that are essential to attainment of the desired properties. The term "discrete" refers to the nature of the matrix as consisting of separate frames, in contradistinction to a unitary frame spanning entire volume of an insulation blanket.

  15. Deformation mechanisms in Ti/TiN multilayer under compressive loading

    International Nuclear Information System (INIS)

    Yang, Wei; Ayoub, Georges; Salehinia, Iman; Mansoor, Bilal; Zbib, Hussein

    2017-01-01

    The promising mechanical, physical and chemical properties of nano-scale metal/ceramic multilayers (MCMs) are of high interest for extreme environment applications. Understanding the plastic deformation mechanisms and the variables affecting those properties is therefore essential. The interface characteristics and the plastic deformation mechanisms under compressive loading in a Ti/TiN multilayer with a semi-coherent interface are numerically investigated. The interface structure of the Ti/TiN interface and the interface misfit dislocation were characterized using molecular dynamic simulations combined with atomically informed Frank-Bilby method. Three possible atomic stacking interface structures are identified according to the crystallographic analysis of the interface. Upon relaxation, large interface areas are occupied with the energetically stable configuration. Furthermore, the higher energy stacking are transformed into misfit dislocations or dislocation nodes. The molecular dynamic compressive stress strain response of the Ti/TiN multilayers exhibited three distinctive peaks. The first peak was generated by the dislocation dissociation of perfect dislocation into pairs of partials dislocation around extended nodes region at the interface. Upon further compression the second peak, identified as the first yielding, resulted from the activation of pyramidal slip planes in the Ti layer. Finally, a third peak identified as the second yielding, occurred when dislocation nucleated/transmitted in/into the TiN layer.

  16. Anisotropy of acoustic properties in paratellurite

    International Nuclear Information System (INIS)

    Parygin, Vladimir N.

    1996-01-01

    One of the peculiarities of the TeO 2 crystal consists of its strong acoustic anisotropy. This anisotropy demonstrates itself by acoustic energy walk-off and anisotropic distortion of an acoustic beam. Four constants completely characterise the acoustic anisotropy of the medium. In this paper these constants are calculated for various directions of the acoustic beam in crystal. (authors)

  17. Characterization of molybdenum/silicon X-ray multilayers

    CERN Document Server

    Nayak, M; Lodha, G S; Shrivastava, A K; Tripathi, P; Sinha, A K; Sawhney, K J S; Nandedkar, R V

    2003-01-01

    Mo/Si multilayers (MLs) with variable Mo thickness were fabricated using electron beam evaporator. Percolation thickness for Mo was determined experimentally. MLs with Mo thickness below percolation show low reflectivity due to discontinuous nature of Mo film. As the number of layer pair increases, the interfacial roughness increases, due to increase in correlated roughness. Extreme ultra violet reflectivity was measured using synchrotron radiation. The fitting result reveals that the graded interface layer exists at each interface. Cross-sectional transmission electron microscopy has been done on some of these MLs.

  18. Finite element analysis of multilayer coextrusion.

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, Matthew Morgan; Schunk, Peter Randall; Baer, Thomas A. (Proctor & Gamble Company, West Chester, OH); Mrozek, Randy A. (Army Research Laboratory, Adelphi, MD); Lenhart, Joseph Ludlow (Army Research Laboratory, Adelphi, MD); Rao, Rekha Ranjana; Collins, Robert (Oak Ridge National Laboratory); Mondy, Lisa Ann

    2011-09-01

    Multilayer coextrusion has become a popular commercial process for producing complex polymeric products from soda bottles to reflective coatings. A numerical model of a multilayer coextrusion process is developed based on a finite element discretization and two different free-surface methods, an arbitrary-Lagrangian-Eulerian (ALE) moving mesh implementation and an Eulerian level set method, to understand the moving boundary problem associated with the polymer-polymer interface. The goal of this work is to have a numerical capability suitable for optimizing and troubleshooting the coextrusion process, circumventing flow instabilities such as ribbing and barring, and reducing variability in layer thickness. Though these instabilities can be both viscous and elastic in nature, for this work a generalized Newtonian description of the fluid is used. Models of varying degrees of complexity are investigated including stability analysis and direct three-dimensional finite element free surface approaches. The results of this work show how critical modeling can be to reduce build test cycles, improve material choices, and guide mold design.

  19. Magnetic anisotropy of lecithin membranes. A new anisotropy susceptometer

    OpenAIRE

    Scholz, F.; Boroske, E.; Helfrich, W.

    1984-01-01

    Cylindrical giant vesicles prepared from egg lecithin and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) are oriented in an external magnetic field and observed by phase contrast microscopy. The anisotropic part of the diamagnetic susceptibility of the lecithin membrane is determined from the distribution of angles between the magnetic field and the long cylinder axis due to thermal fluctuations. The anisotropy of DMPC is found to be larger by a factor of 2 than that of egg lecithin. This...

  20. Plasticity and microstructure of epitaxial Ag/Ni multilayers; Mechanische Eigenschaften und Mikrostruktur epitaktischer Ag/Ni-Multilagenschichten

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Tobias K.

    2007-10-15

    To meet the still increasing technical demands of new materials, it is required to improve basic knowledge of thin films and multilayers. This thesis describes the microstructure and mechanical behaviour of thin epitaxial Ag/Ni-multilayers. Former investigations were only done on polycrystalline multilayers or epitaxial single layers. The manufacture of epitaxial Ag/Ni-multilayers on (111) orientated Si-substrates was performed by a magnetron sputtering technique under ultra high vacuum (UHV). The thickness of the alternating Ag- and Ni-layers varies between 100 and 400 nm, the thickness of the whole film varies between 200 and 800 nm. Hardness and flow stress of Ag/Ni-multilayers were measured with a nanoindentation technique, a substrate curvature method and by X-ray diffraction. The hardness of these multilayers varies between 1.5 and 2.0 GPa. The Ag single film hardness is 0.5 GPa and Ni film 1.8 GPa. The flow stress of the Ag/Ni-multilayers varies between 350 and 800 MPa. The Ag single layer shows a flow stress of 100 MPa and Ni of 450 MPa. Both hardness and flow stress increase with decreasing layer thickness. In situ TEM and HRTEM experiments showed a semicoherent Ag/Ni-interface. It was observed that these interfaces act as sources and sinks. Dislocation loops formed at the interface expand and shrink according to the stress state. They combine with loops from the opposite interface or with the interface itself and form threading dislocations. Dislocation loops penetrating an interface were not observed. Results were compared with various models which simulate flow stress in thin films and multilayers. The most important models are calculated by Nix-Freund, the Source-model after von Blanckenhagen and the Hall-Petch-model. (orig.)

  1. Magnetic Anisotropy by Rashba Spin-Orbit Coupling in Antiferromagnetic Thin Films

    Science.gov (United States)

    Ieda, Jun'ichi; Barnes, Stewart E.; Maekawa, Sadamichi

    2018-05-01

    Magnetic anisotropy in an antiferromagnet (AFM) with inversion symmetry breaking (ISB) is investigated. The magnetic anisotropy energy (MAE) resulting from the Rashba spin-orbit and s-d type exchange interactions is determined for two different models of AFMs. The global ISB model, representing the effect of a surface, an interface, or a gating electric field, results in an easy-plane magnetic anisotropy. In contrast, for a local ISB model, i.e., for a noncentrosymmetric AFM, perpendicular magnetic anisotropy (PMA) arises. Both results differ from the ferromagnetic case, in which the result for PMA depends on the band structure and dimensionality. These MAE contributions play a key role in determining the direction of the Néel order parameter in antiferromagnetic nanostructures, and reflect the possibility of electrical-field control of the Néel vector.

  2. First-principles calculations for the elastic properties of Ni-base model superalloys: Ni/Ni3Al multilayers

    International Nuclear Information System (INIS)

    Yun-Jiang, Wang; Chong-Yu, Wang

    2009-01-01

    A model system consisting of Ni[001](100)/Ni 3 Al[001](100) multi-layers are studied using the density functional theory in order to explore the elastic properties of single crystal Ni-based superalloys. Simulation results are consistent with the experimental observation that rafted Ni-base superalloys virtually possess a cubic symmetry. The convergence of the elastic properties with respect to the thickness of the multilayers are tested by a series of multilayers from 2γ'+2γ to 10γ'+10γ atomic layers. The elastic properties are found to vary little with the increase of the multilayer's thickness. A Ni/Ni 3 Al multilayer with 10γ'+10γ atomic layers (3.54 nm) can be used to simulate the mechanical properties of Ni-base model superalloys. Our calculated elastic constants, bulk modulus, orientation-dependent shear modulus and Young's modulus, as well as the Zener anisotropy factor are all compatible with the measured results of Ni-base model superalloys R1 and the advanced commercial superalloys TMS-26, CMSX-4 at a low temperature. The mechanical properties as a function of the γ' phase volume fraction are calculated by varying the proportion of the γ and γ' phase in the multilayers. Besides, the mechanical properties of two-phase Ni/Ni 3 Al multilayer can be well predicted by the Voigt–Reuss–Hill rule of mixtures. (classical areas of phenomenology)

  3. Time-Dependent Thermally-Driven Interfacial Flows in Multilayered Fluid Structures

    Science.gov (United States)

    Haj-Hariri, Hossein; Borhan, A.

    1996-01-01

    A computational study of thermally-driven convection in multilayered fluid structures will be performed to examine the effect of interactions among deformable fluid-fluid interfaces on the structure of time-dependent flow in these systems. Multilayered fluid structures in two models configurations will be considered: the differentially heated rectangular cavity with a free surface, and the encapsulated cylindrical liquid bridge. An extension of a numerical method developed as part of our recent NASA Fluid Physics grant will be used to account for finite deformations of fluid-fluid interfaces.

  4. Anisotropy of domain wall resistance

    Science.gov (United States)

    Viret; Samson; Warin; Marty; Ott; Sondergard; Klein; Fermon

    2000-10-30

    The resistive effect of domain walls in FePd films with perpendicular anisotropy was studied experimentally as a function of field and temperature. The films were grown directly on MgO substrates, which induces an unusual virgin magnetic configuration composed of 60 nm wide parallel stripe domains. This allowed us to carry out the first measurements of the anisotropy of domain wall resistivity in the two configurations of current perpendicular and parallel to the walls. At 18 K, we find 8.2% and 1.3% for the domain wall magnetoresistance normalized to the wall width (8 nm) in these two respective configurations. These values are consistent with the predictions of Levy and Zhang.

  5. Finite element modeling of multilayered structures of fish scales.

    Science.gov (United States)

    Chandler, Mei Qiang; Allison, Paul G; Rodriguez, Rogie I; Moser, Robert D; Kennedy, Alan J

    2014-12-01

    The interlinked fish scales of Atractosteus spatula (alligator gar) and Polypterus senegalus (gray and albino bichir) are effective multilayered armor systems for protecting fish from threats such as aggressive conspecific interactions or predation. Both types of fish scales have multi-layered structures with a harder and stiffer outer layer, and softer and more compliant inner layers. However, there are differences in relative layer thickness, property mismatch between layers, the property gradations and nanostructures in each layer. The fracture paths and patterns of both scales under microindentation loads were different. In this work, finite element models of fish scales of A. spatula and P. senegalus were built to investigate the mechanics of their multi-layered structures under penetration loads. The models simulate a rigid microindenter penetrating the fish scales quasi-statically to understand the observed experimental results. Study results indicate that the different fracture patterns and crack paths observed in the experiments were related to the different stress fields caused by the differences in layer thickness, and spatial distribution of the elastic and plastic properties in the layers, and the differences in interface properties. The parametric studies and experimental results suggest that smaller fish such as P. senegalus may have adopted a thinner outer layer for light-weighting and improved mobility, and meanwhile adopted higher strength and higher modulus at the outer layer, and stronger interface properties to prevent ring cracking and interface cracking, and larger fish such as A. spatula and Arapaima gigas have lower strength and lower modulus at the outer layers and weaker interface properties, but have adopted thicker outer layers to provide adequate protection against ring cracking and interface cracking, possibly because weight is less of a concern relative to the smaller fish such as P. senegalus. Published by Elsevier Ltd.

  6. X-ray scattering in giant magneto-resistive multilayers

    International Nuclear Information System (INIS)

    Fulthorpe, B.D.

    1999-01-01

    The scattering mechanisms responsible for Giant Magneto-Resistance (GMR) in magnetic multilayers are believed to be related to many aspects of the multilayer structure. X-ray scattering techniques provide a powerful method with which to study the bulk and interface morphology in these systems, and are therefore crucial in developing an understanding of the dominant factors influencing the magnitude of the GMR. Reflectivity measurements performed on a series of Co/Cu multilayers, sputter deposited onto etched silicon, reveal no variation in the interface roughness with etching voltage, the thickness of the individual layers also remaining constant. The observed decrease in the GMR cannot, therefore, be attributed to variations in spacer thickness or interfacial spin-independent scattering. Electron and X-ray Diffraction measurements suggest the reduction in GMR is due to a loss of antiferromagnetic coupling associated with a transformation of the texture from a randomly oriented to well oriented (111) polycrystalline texture, and subsequent reduction in the volume fraction of (100) oriented grains. Interfaces within Co/Cu are found to propagate with a high degree of conformality with increasing bilayer number, with an out-of-plane correlation length well in excess of 300A. In contrast, the Co/Pt system exhibits a limiting out-of-plane correlation length of the order of 350A arising from a columnar growth mode. X-ray Reflectivity and Diffraction measurements provide' no structural interpretation for the 3-fold enhancement in the rate of increase of the saturation conductivity, as a function of spacer thickness, in Fe/Au (100) compared to Fe/Au (111), or why large oscillations in the GMR occur for the (100) orientation only. Such observations are, however, consistent with the existence of a channelling mechanism in Fe/Au (100). Grazing Incidence Fluorescence data indicates that Nb acts as a surfactant in Fe/Au (111) growth on sapphire. The influence of different

  7. [Cosmic Microwave Background (CMB) Anisotropies

    Science.gov (United States)

    Silk, Joseph

    1998-01-01

    One of the main areas of research is the theory of cosmic microwave background (CMB) anisotropies and analysis of CMB data. Using the four year COBE data we were able to improve existing constraints on global shear and vorticity. We found that, in the flat case (which allows for greatest anisotropy), (omega/H)0 less than 10(exp -7), where omega is the vorticity and H is the Hubble constant. This is two orders of magnitude lower than the tightest, previous constraint. We have defined a new set of statistics which quantify the amount of non-Gaussianity in small field cosmic microwave background maps. By looking at the distribution of power around rings in Fourier space, and at the correlations between adjacent rings, one can identify non-Gaussian features which are masked by large scale Gaussian fluctuations. This may be particularly useful for identifying unresolved localized sources and line-like discontinuities. Levin and collaborators devised a method to determine the global geometry of the universe through observations of patterns in the hot and cold spots of the CMB. We have derived properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We represent results for angular resolutions ranging from 5 arcmin to 20 arcmin (antenna FWHM), scales that are relevant for the MAP and COBRA/SAMBA space missions and the ground-based interferometer. Results related to galaxy formation and evolution are also discussed.

  8. Kinetic Interface

    DEFF Research Database (Denmark)

    2009-01-01

    A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises.......A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises....

  9. Multilayer graphene rubber nanocomposites

    Science.gov (United States)

    Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas

    2016-05-01

    Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m2/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development.

  10. Exchange anisotropy pinning of a standing spin-wave mode

    Science.gov (United States)

    Magaraggia, R.; Kennewell, K.; Kostylev, M.; Stamps, R. L.; Ali, M.; Greig, D.; Hickey, B. J.; Marrows, C. H.

    2011-02-01

    Standing spin waves in a thin film are used as sensitive probes of interface pinning induced by an antiferromagnet through exchange anisotropy. Using coplanar waveguide ferromagnetic resonance, pinning of the lowest energy spin-wave thickness mode in Ni80Fe20/Ir25Mn75 exchange-biased bilayers was studied for a range of Ir25Mn75 thicknesses. We show that pinning of the standing mode can be used to amplify, relative to the fundamental resonance, frequency shifts associated with exchange bias. The shifts provide a unique “fingerprint” of the exchange bias and can be interpreted in terms of an effective ferromagnetic film thickness and ferromagnet-antiferromagnet interface anisotropy. Thermal effects are studied for ultrathin antiferromagnetic Ir25Mn75 thicknesses, and the onset of bias is correlated with changes in the pinning fields. The pinning strength magnitude is found to grow with cooling of the sample, while the effective ferromagnetic film thickness simultaneously decreases. These results suggest that exchange bias involves some deformation of magnetic order in the interface region.

  11. Iron-platinum multilayer thin film reactions to form L1(0) iron-platinum and exchange spring magnets

    Science.gov (United States)

    Yao, Bo

    FePt films with the L10 phase have potential applications for magnetic recording and permanent magnets due to its high magnetocrystalline anisotropy energy density. Heat treatment of [Fe/Pt] n multilayer films is one approach to form the L10 FePt phase through a solid state reaction. This thesis has studied the diffusion and reaction of [Fe/Pt]n multilayer films to form the L10 FePt phase and has used this understanding to construct exchange spring magnets. The process-structure-property relations of [Fe/Pt] n multilayer films were systematically examined. The transmission electron microscopy (TEM) study of the annealed multilayers indicates that the Pt layer grows at the expense of Fe during annealing, forming a disordered fcc FePt phase by the interdiffusion of Fe into Pt. This thickening of the fcc Pt layer can be attributed to the higher solubilities of Fe into fcc Pt, as compared to the converse. For the range of film thickness studied, a continuous L10 FePt product layer that then thickens with further annealing is not found. Instead, the initial L10 FePt grains are distributed mainly on the grain boundaries within the fcc FePt layer and at the Fe/Pt interfaces and further transformation of the sample to the ordered L10 FePt phase proceeds coupled with the growth of the initial L10 FePt grains. A comprehensive study of annealed [Fe/Pt]n films is provided concerning the phase fraction, grain size, nucleation/grain density, interdiffusivity, long-range order parameter, and texture, as well as magnetic properties. A method based on hollow cone dark field TEM is introduced to measure the volume fraction, grain size, and density of ordered L10 FePt phase grains in the annealed films, and low-angle X-ray diffraction is used to measure the effective Fe-Pt interdiffusivity. The process-structure-properties relations of two groups of samples with varying substrate temperature and periodicity are reported. The results demonstrate that the processing parameters

  12. Exchange anisotropy and micromagnetic properties of PtMn/NiFe bilayers

    International Nuclear Information System (INIS)

    Pokhil, Taras; Linville, Eric; Mao, Sining

    2001-01-01

    Magnetic microstructure, exchange induced uniaxial and unidirectional anisotropy and structural transformation have been studied in PtMn/NiFe bilayer films and small elements as a function of annealing time. The relationship between the fcc-fct ordering phase transformation in PtMn and the development of exchange induced magnetic properties in PtMn/NiFe bilayers is complicated by the fact that the transformation occurs throughout the entire volume of the PtMn film, while the exchange between the layers is predominantly an interface effect. Consequently, the development of the exchange anisotropy should depend primarily on the character of the structural transformation at the interface between PtMn and NiFe. The purpose of this article is to correlate the volume phase transformation in PtMn to the development of exchange anisotropy and micromagnetic behavior in PtMn/NiFe bilayers. The interface structure can be inferred from the anisotropy and micromagnetic measurements, leading to a model that explains the relationship between the volume and interface transformation structures in PtMn, and magnetic properties of the bilayers. The structure and magnetic properties were characterized by x-ray diffraction, vibrating sample magnetometry, and magnetic force microscopy. [copyright] 2001 American Institute of Physics

  13. Exchange anisotropy as a probe of antiferromagnetism in expanded face-centered-tetragonal Mn(001) layers

    NARCIS (Netherlands)

    Kohlhepp, J.T.; Wieldraaijer, H.; Jonge, de W.J.M.

    2006-01-01

    Manganese (Mn) grows coherent and with an expanded metastable face-centered-tetragonal (e-fct) structure on ultrathin fct Co(001)/Cu(001) template layers. From the temp. dependence of the obsd. unidirectional Mn/Co interface exchange anisotropy, an antiferromagnetic state with a blocking temp.

  14. Self-assembled metal nano-multilayered film prepared by co-sputtering method

    Science.gov (United States)

    Xie, Tianle; Fu, Licai; Qin, Wen; Zhu, Jiajun; Yang, Wulin; Li, Deyi; Zhou, Lingping

    2018-03-01

    Nano-multilayered film is usually prepared by the arrangement deposition of different materials. In this paper, a self-assembled nano-multilayered film was deposited by simultaneous sputtering of Cu and W. The Cu/W nano-multilayered film was accumulated by W-rich layer and Cu-rich layer. Smooth interfaces with consecutive composition variation and semi-coherent even coherent relationship were identified, indicating that a spinodal-like structure with a modulation wavelength of about 20 nm formed during co-deposition process. The participation of diffusion barrier element, such as W, is believed the essential to obtain the nano-multilayered structure besides the technological parameters.

  15. Fabrication and Characteristics of Al/PTFE Multilayers and Application in Micro-initiator

    Science.gov (United States)

    Zhang, Yuxin; Jiang, Hongchuan; Zhao, Xiaohui; Zhang, Wanli; Li, Yanrong

    2017-12-01

    In this paper, a micro-initiator was designed and fabricated by integrating Al/PTFE multilayers with a Cu film bridge. The regularity layer structure and interface composition of Al/PTFE multilayers was analysed by transmission electron microscope and X-ray photoelectron spectroscopy, respectively. The heat release reaction in Al/PTFE multilayers can be triggered with reaction temperature of 430 °C, and the overall heat of reaction is 3192 J/g. Al/PTFE multilayers with bilayer thickness of 200 nm was alternately deposited on a Cu film bridge to improve the electric explosion performances. Compared to Cu film bridge, the Al/PTFE/Cu integrated film bridge exhibits improved performances with longer explosion duration time, more violent explosion phenomenon and larger quantities of ejected product particles.

  16. Kossel interferences of proton-induced X-ray emission lines in periodic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Meiyi; Le Guen, Karine; André, Jean-Michel [Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75231 Paris cedex 05 (France); CNRS UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75231 Paris cedex 05 (France); Ilakovac, Vita [Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75231 Paris cedex 05 (France); CNRS UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75231 Paris cedex 05 (France); Université de Cergy-Pontoise, F-95031 Cergy-Pontoise (France); Vickridge, Ian [Sorbonne Universités, UPMC Univ Paris 06, Institut des NanoSciences de Paris, 4 place Jussieu, boîte courrier 840, F-75252 Paris cedex 05 (France); CNRS UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, boîte courrier 840, F-75252 Paris cedex 05 (France); Schmaus, Didier [Sorbonne Universités, UPMC Univ Paris 06, Institut des NanoSciences de Paris, 4 place Jussieu, boîte courrier 840, F-75252 Paris cedex 05 (France); CNRS UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, boîte courrier 840, F-75252 Paris cedex 05 (France); Université Paris Diderot-P7, F-75205 Paris cedex 13 (France); and others

    2016-11-01

    The Kossel interferences generated by characteristic X-ray lines produced inside a periodic multilayer have been observed upon proton irradiation, by submitting a Cr/B{sub 4}C/Sc multilayer stack to 2 MeV protons and observing the intensity of the Sc and Cr Kα characteristic emissions as a function of the detection angle. When this angle is close to the Bragg angle corresponding to the emission wavelength and period of the multilayer, an oscillation of the measured intensity is detected. The results are in good agreement with a model based on the reciprocity theorem. The combination of the Kossel measurements and their simulation, will be a useful tool to obtain a good description of the multilayer stack and thus to study nanometer-thick layers and their interfaces.

  17. Ultra-short-period WC/SiC multilayer coatings for x-ray applications

    International Nuclear Information System (INIS)

    Fernández-Perea, Mónica; Pivovaroff, Mike J.; Soufli, Regina; Alameda, Jennifer; Mirkarimi, Paul; Descalle, Marie-Anne; Baker, Sherry L.; McCarville, Tom; Ziock, Klaus; Hornback, Donald; Romaine, Suzanne; Bruni, Ric; Zhong, Zhong; Honkimäki, Veijo; Ziegler, Eric; Christensen, Finn E.; Jakobsen, Anders C.

    2013-01-01

    Multilayer coatings enhance x-ray mirror performance at incidence angles steeper than the critical angle, allowing for improved flux, design flexibility and facilitating alignment. In an attempt to extend the use of multilayer coatings to photon energies higher than previously achieved, we have developed multilayers with ultra-short periods between 1 and 2 nm based on the material system WC/SiC. This material system was selected because it possesses very sharp and stable interfaces. In this article, we show highlights from a series of experiments performed in order to characterize the stress, microstructure and morphology of the multilayer films, as well as their reflective performance at photon energies from 8 to 384 keV

  18. Sectioning of multilayers to make a multilayer Laue lens

    International Nuclear Information System (INIS)

    Kang, Hyon Chol; Stephenson, G. Brian; Liu Chian; Conley, Ray; Khachatryan, Ruben; Wieczorek, Michael; Macrander, Albert T.; Yan Hanfei; Maser, Joerg; Hiller, Jon; Koritala, Rachel

    2007-01-01

    We report a process to fabricate multilayer Laue lenses (MLL's) by sectioning and thinning multilayer films. This method can produce a linear zone plate structure with a very large ratio of zone depth to width (e.g., >1000), orders of magnitude larger than can be attained with photolithography. Consequently, MLL's are advantageous for efficient nanofocusing of hard x rays. MLL structures prepared by the technique reported here have been tested at an x-ray energy of 19.5 keV, and a diffraction-limited performance was observed. The present article reports the fabrication techniques that were used to make the MLL's

  19. High Field Linear Magnetoresistance Sensors with Perpendicular Anisotropy L10-FePt Reference Layer

    Directory of Open Access Journals (Sweden)

    X. Liu

    2016-01-01

    Full Text Available High field linear magnetoresistance is an important feature for magnetic sensors applied in magnetic levitating train and high field positioning measurements. Here, we investigate linear magnetoresistance in Pt/FePt/ZnO/Fe/Pt multilayer magnetic sensor, where FePt and Fe ferromagnetic layers exhibit out-of-plane and in-plane magnetic anisotropy, respectively. Perpendicular anisotropy L10-FePt reference layer with large coercivity and high squareness ratio was obtained by in situ substrate heating. Linear magnetoresistance is observed in this sensor in a large range between +5 kOe and −5 kOe with the current parallel to the film plane. This L10-FePt based sensor is significant for the expansion of linear range and the simplification of preparation for future high field magnetic sensors.

  20. Design and fabrication of heat resistant multilayers

    International Nuclear Information System (INIS)

    Thorne, J.M.; Knight, L.V.; Peterson, B.G.; Perkins, R.T.; Gray, K.J.

    1986-01-01

    Many promising applications of multilayer x-ray optical elements subject them to intense radiation. This paper discusses the selection of optimal pairs of materials to resist heat damage and presents simulations of multilayer performance under extreme heat loadings

  1. Anisotropy of the cosmic background radiation

    International Nuclear Information System (INIS)

    Silk, J.

    1988-01-01

    The characteristics of the cosmic microwave background radiation (CBR) are reviewed, focusing on intrinsic anisotropies caused by primordial matter fluctuations. The basic elements of the CBR are outlined and the contributions to anisotropy at different angular scales are discussed. Possible fluctuation spectra that can generate the observed large-scale structure of the universe through gravitational instability and nonlinear evolution are examined and compared with observational searches for cosmic microwave anisotropies. 21 refs

  2. A topological multilayer model of the human body.

    Science.gov (United States)

    Barbeito, Antonio; Painho, Marco; Cabral, Pedro; O'Neill, João

    2015-11-04

    Geographical information systems deal with spatial databases in which topological models are described with alphanumeric information. Its graphical interfaces implement the multilayer concept and provide powerful interaction tools. In this study, we apply these concepts to the human body creating a representation that would allow an interactive, precise, and detailed anatomical study. A vector surface component of the human body is built using a three-dimensional (3-D) reconstruction methodology. This multilayer concept is implemented by associating raster components with the corresponding vector surfaces, which include neighbourhood topology enabling spatial analysis. A root mean square error of 0.18 mm validated the three-dimensional reconstruction technique of internal anatomical structures. The expansion of the identification and the development of a neighbourhood analysis function are the new tools provided in this model.

  3. Effect of swift heavy ion-irradiation on Cr/Fe/Ni multilayers

    International Nuclear Information System (INIS)

    Gupta, Ratnesh; Gupta, Ajay; Avasthi, D.K.; Principi, G.; Tosello, C.

    1999-01-01

    A multilayer film having overall composition Fe 50 Cr 25 Ni 25 , was irradiated successively by 80 MeV Si ions and Ag ions of 150 and 200 MeV energy. The energy deposited in the multilayer in the form of electronic excitations results in significant modification at the interfaces. The interfacial roughness increases in the system after the irradiations as revealed by X-ray reflectivity measurement. Moessbauer measurements provide evidence of intermixing after the irradiation by 200 MeV Ag ions. Comparison of heavy ion irradiated multilayer has been done with annealed and low energy ion irradiated samples. Results suggest that the phases formed at the interfaces of iron as a result of electronic energy loss are similar to those in the cases of thermal diffusion and keV energy ion beam irradiation

  4. Development of neutron diffuse scattering analysis code by thin film and multilayer film

    International Nuclear Information System (INIS)

    Soyama, Kazuhiko

    2004-01-01

    To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering by thin film, roughness of surface of thin film, correlation function, neutron propagation by thin film, diffuse scattering by DWBA theory, measurement model, SDIFFF (neutron diffuse scattering analysis program by thin film) and simulation results are explained. On neutron diffuse scattering by multilayer film, roughness of multilayer film, principle of diffuse scattering, measurement method and simulation examples by MDIFF (neutron diffuse scattering analysis program by multilayer film) are explained. (S.Y.)To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering

  5. Magnetic Ultrathin Films: Multilayers and Surfaces, Interfaces and Characterization

    Science.gov (United States)

    1993-04-01

    Zaluska, Z. Altounian, 1O. Str6m- Olsen , Y. Huai, and R.W. Cochrane GIANT MAGNETORESISTANCE AND STRUCTURE OF PHASE- SEGREGATED EPITAXIAL METALS 411 R.F...helpful advice in the design of the MOKE magnetome- ter, Byungwoo Park for help with’ the earlier part of this project and lastly, Selmer Wong for...501 Paduani. C.. 333 Storm, D., 651 Panissod, P.. 289 Str6m- Olsen . J.O.. 405 Pappas, D.P., 369, 451, 457, 619 Sugita, Yutaka. 257 Parker. M.R., 73, 191

  6. The mechanical behavior of nanoscale metallic multilayers: A survey

    Science.gov (United States)

    Zhou, Q.; Xie, J. Y.; Wang, F.; Huang, P.; Xu, K. W.; Lu, T. J.

    2015-06-01

    The mechanical behavior of nanoscale metallic multilayers (NMMs) has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces existing in the NMMs dictates the unique behavior of this special class of structural composite materials. While there have been a number of reviews on the mechanical mechanism of microlaminates, the rapid development of nanotechnology brought a pressing need for an overview focusing exclusively on a property-based definition of the NMMs, especially their size-dependent microstructure and mechanical performance. This article attempts to provide a comprehensive and up-to-date review on the microstructure, mechanical property and plastic deformation physics of NMMs. We hope this review could accomplish two purposes: (1) introducing the basic concepts of scaling and dimensional analysis to scientists and engineers working on NMM systems, and (2) providing a better understanding of interface behavior and the exceptional qualities the interfaces in NMMs display at atomic scale.

  7. Azimuthal anisotropy measurements by STAR

    Science.gov (United States)

    Yi, Li

    2014-06-01

    The recent study of centrality and transverse momentum (pT) dependence of inclusive charged hardron elliptic anisotropy (v2) at midrapidity (|η|<1.0) in Au+Au collision at √{sNN}=7.7,11.5,19.6,27, and 39 GeV in STAR Beam Energy Scan program is presented. We show that the observed increase of inclusive v2 is mainly due to the average pT increase with energy. In Au+Au 200 GeV collisions, the triangular anisotropy (v3) measurements highly depend on measurement methods; v3 is strongly dependent on Δη. The difference between two- and four-particle cumulants v2{2} and v2{4} for Au+Au and Cu+Cu collision at √{sNN}=62.4 and 200 GeV is used to explore flow fluctuations. Furthermore, by exploiting the symmetry of average flow in pseudorapidity η about midrapidity, the Δη-dependent and independent components are separated using v2{2} and v2{4}.

  8. Azimuthal anisotropy measurements by STAR

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Li

    2014-06-15

    The recent study of centrality and transverse momentum (p{sub T}) dependence of inclusive charged hardron elliptic anisotropy (v{sub 2}) at midrapidity (|η|<1.0) in Au+Au collision at √(s{sub NN})=7.7,11.5,19.6,27, and39 GeV in STAR Beam Energy Scan program is presented. We show that the observed increase of inclusive v{sub 2} is mainly due to the average p{sub T} increase with energy. In Au+Au 200 GeV collisions, the triangular anisotropy (v{sub 3}) measurements highly depend on measurement methods; v{sub 3} is strongly dependent on Δη. The difference between two- and four-particle cumulants v{sub 2}{2} and v{sub 2}{4} for Au+Au and Cu+Cu collision at √(s{sub NN})=62.4 and 200 GeV is used to explore flow fluctuations. Furthermore, by exploiting the symmetry of average flow in pseudorapidity η about midrapidity, the Δη-dependent and independent components are separated using v{sub 2}{2} and v{sub 2}{4}.

  9. Azimuthal anisotropy measurements by STAR

    International Nuclear Information System (INIS)

    Yi, Li

    2014-01-01

    The recent study of centrality and transverse momentum (p T ) dependence of inclusive charged hardron elliptic anisotropy (v 2 ) at midrapidity (|η|<1.0) in Au+Au collision at √(s NN )=7.7,11.5,19.6,27, and39 GeV in STAR Beam Energy Scan program is presented. We show that the observed increase of inclusive v 2 is mainly due to the average p T increase with energy. In Au+Au 200 GeV collisions, the triangular anisotropy (v 3 ) measurements highly depend on measurement methods; v 3 is strongly dependent on Δη. The difference between two- and four-particle cumulants v 2 {2} and v 2 {4} for Au+Au and Cu+Cu collision at √(s NN )=62.4 and 200 GeV is used to explore flow fluctuations. Furthermore, by exploiting the symmetry of average flow in pseudorapidity η about midrapidity, the Δη-dependent and independent components are separated using v 2 {2} and v 2 {4}

  10. Transverse peltier effect in Pb-Bi{sub 2}Te{sub 3} multilayer structures

    Energy Technology Data Exchange (ETDEWEB)

    Reitmaier, Christina; Walther, Franziska; Kyarad, Amir; Lengfellner, Hans [University of Regensburg (Germany)

    2009-07-01

    Metal-semiconductor multilayer structures show, according to model calculations, large anisotropy in their electrical and thermal transport properties. Multilayer stacks consisting of alternating layers of Pb and n-type Bi{sub 2}Te{sub 3} and prepared by a heating procedure displayed large thermoelectric anisotropy up to {delta}S{approx}200 {mu} V/K, depending on the thickness ratio p=d{sub BiTe}/d{sub Pb}, where d{sub BiTe} and d{sub Pb} are the thicknesses of Bi{sub 2}Te{sub 3} and Pb layers, respectively. From multilayer stacks, tilted samples with layers inclined with respect to the sample surface where obtained by cutting stacks obliquely to the stack axis. Non-zero off-diagonal elements in the Seebeck-tensor describing the thermopower of tilted samples allow for the occurance of a transverse Peltier effect. Experimental results demonstrate cooling by the transverse Peltier effect and are compared to model calculations.

  11. Bayesian Markov Chain Monte Carlo inversion for weak anisotropy parameters and fracture weaknesses using azimuthal elastic impedance

    Science.gov (United States)

    Chen, Huaizhen; Pan, Xinpeng; Ji, Yuxin; Zhang, Guangzhi

    2017-08-01

    A system of aligned vertical fractures and fine horizontal shale layers combine to form equivalent orthorhombic media. Weak anisotropy parameters and fracture weaknesses play an important role in the description of orthorhombic anisotropy (OA). We propose a novel approach of utilizing seismic reflection amplitudes to estimate weak anisotropy parameters and fracture weaknesses from observed seismic data, based on azimuthal elastic impedance (EI). We first propose perturbation in stiffness matrix in terms of weak anisotropy parameters and fracture weaknesses, and using the perturbation and scattering function, we derive PP-wave reflection coefficient and azimuthal EI for the case of an interface separating two OA media. Then we demonstrate an approach to first use a model constrained damped least-squares algorithm to estimate azimuthal EI from partially incidence-phase-angle-stack seismic reflection data at different azimuths, and then extract weak anisotropy parameters and fracture weaknesses from the estimated azimuthal EI using a Bayesian Markov Chain Monte Carlo inversion method. In addition, a new procedure to construct rock physics effective model is presented to estimate weak anisotropy parameters and fracture weaknesses from well log interpretation results (minerals and their volumes, porosity, saturation, fracture density, etc.). Tests on synthetic and real data indicate that unknown parameters including elastic properties (P- and S-wave impedances and density), weak anisotropy parameters and fracture weaknesses can be estimated stably in the case of seismic data containing a moderate noise, and our approach can make a reasonable estimation of anisotropy in a fractured shale reservoir.

  12. Ultra-short-period WC/SiC multilayer coatings for x-ray applications

    DEFF Research Database (Denmark)

    Fernandez-Perea, M.; Pivovaroff, M. J.; Soufli, R.

    2013-01-01

    developed multilayers with ultra-shortperiods between 1 and 2 nm based on the material system WC/SiC. This material system was selected because it possesses very sharp and stable interfaces. In this article, we show highlights from a series of experiments performed in order to characterize the stress...

  13. Electrodeposition mechanism and corrosion behavior of multilayer nanocrystalline nickel-tungsten alloy

    DEFF Research Database (Denmark)

    Allahyarzadeh, M.H.; Aliofkhazraei, M.; Rouhaghdam, A. Sabour

    2017-01-01

    that the diffusive species of the electrolyte encountered a larger interface in multilayer structures. Hence, they spread out along and throughout the active layers; which significantly delays the penetration towards the substrate. Enhanced service life of the noble layers is achieved owing to the galvanic effect...

  14. Multilayer polymer pipes failure assessment based on a fracture mechanics approach

    Czech Academy of Sciences Publication Activity Database

    Hutař, Pavel; Zouhar, Michal; Náhlík, Luboš; Ševčík, Martin; Máša, Bohuslav

    2013-01-01

    Roč. 33, OCT (2013), s. 151-162 ISSN 1350-6307 R&D Projects: GA ČR(CZ) GAP108/12/1560 Institutional support: RVO:68081723 Keywords : Multilayer pipes * Generalised stress intensity factor * Material interface * Slow crack growth * Polyolefin pipes Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.130, year: 2013

  15. On correction of model of stabilization of distribution of concentration of radiation defects in a multilayer structure with account experiment data

    Science.gov (United States)

    Pankratov, E. L.

    2018-05-01

    We introduce a model of redistribution of point radiation defects, their interaction between themselves and redistribution of their simplest complexes (divacancies and diinterstitials) in a multilayer structure. The model gives a possibility to describe qualitatively nonmonotonicity of distributions of concentrations of radiation defects on interfaces between layers of the multilayer structure. The nonmonotonicity was recently found experimentally. To take into account the nonmonotonicity we modify recently used in literature model for analysis of distribution of concentration of radiation defects. To analyze the model we used an approach of solution of boundary problems, which could be used without crosslinking of solutions on interfaces between layers of the considered multilayer structures.

  16. Multilayer Controller for Outdoor Vehicle

    DEFF Research Database (Denmark)

    Reske-Nielsen, Anders; Mejnertsen, Asbjørn; Andersen, Nils Axel

    2006-01-01

    A full software and hardware solution has been designed, implemented and tested for control of a small agricultural automatic tractor. The objective was to realise a user-friendly, multi-layer controller architecture for an outdoor platform. The collaborative research work was done as a part of a...

  17. New developments in Ni/Ti multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, I; Hoghoj, P [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    It is now 20 years since super-mirrors were first used as a neutron optical element. Since then the field of multilayer neutron-optics has matured with multilayers finding their way to application in many neutron scattering instruments. However, there is still room for progress in terms of multilayer quality, performance and application. Along with work on multilayers for neutron polarisation Ni/Ti super-mirrors have been optimised. The state-of-the-art Ni/Ti super-mirror performance and the results obtained in two neutron-optics applications of Ni/Ti multilayers are presented. (author).

  18. Interface Consistency

    DEFF Research Database (Denmark)

    Staunstrup, Jørgen

    1998-01-01

    This paper proposes that Interface Consistency is an important issue for the development of modular designs. Byproviding a precise specification of component interfaces it becomes possible to check that separately developedcomponents use a common interface in a coherent matter thus avoiding a very...... significant source of design errors. Awide range of interface specifications are possible, the simplest form is a syntactical check of parameter types.However, today it is possible to do more sophisticated forms involving semantic checks....

  19. Growth and magnetic study of sputtered Fe/Al multilayers

    International Nuclear Information System (INIS)

    Cherif, S.M.; Bouziane, K.; Roussigne, Y.; Al-Busaidy, M.

    2007-01-01

    Brillouin light scattering (BLS) and vibrating sample magnetometry (VSM) were used to study the effect of interfacial intermixing and microstructure on the magnetic properties of DC magnetron sputtered Fe/Al multilayers (MLs) on Si(1 0 0) substrate. Three samples with nominal composition [Al (4 nm)/Fe (3.7 nm)] x18 and deposited under different negative DC bias voltages (V b = -50, -200 and -400 V) have been investigated. The X-ray diffraction results indicate that the FeAl MLs have a poor crystallinity with no evidence of the absence of B2 phase. The grazing X-ray reflectivity results suggest that the interfacial roughness and intermixing were gradually reduced from 0.7 to 0.5 nm (±0.05 nm) by increasing V b from -50 to -400 V. The magnetization measurements demonstrate the presence of in-plane uniaxial anisotropy and magnetically dead interfacial layers. The BLS results reveal spin-wave surface modes whose frequencies also depend on the applied V b . The same trend upon V b was observed for the perpendicular and in-plane anisotropies

  20. Growth and magnetic study of sputtered Fe/Al multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cherif, S.M. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France); Bouziane, K. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France) and Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)]. E-mail: bouzi@squ.edu.om; Roussigne, Y. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France); Al-Busaidy, M. [Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)

    2007-03-15

    Brillouin light scattering (BLS) and vibrating sample magnetometry (VSM) were used to study the effect of interfacial intermixing and microstructure on the magnetic properties of DC magnetron sputtered Fe/Al multilayers (MLs) on Si(1 0 0) substrate. Three samples with nominal composition [Al (4 nm)/Fe (3.7 nm)]{sub x18} and deposited under different negative DC bias voltages (V {sub b} = -50, -200 and -400 V) have been investigated. The X-ray diffraction results indicate that the FeAl MLs have a poor crystallinity with no evidence of the absence of B2 phase. The grazing X-ray reflectivity results suggest that the interfacial roughness and intermixing were gradually reduced from 0.7 to 0.5 nm ({+-}0.05 nm) by increasing V {sub b} from -50 to -400 V. The magnetization measurements demonstrate the presence of in-plane uniaxial anisotropy and magnetically dead interfacial layers. The BLS results reveal spin-wave surface modes whose frequencies also depend on the applied V{sub b}. The same trend upon V {sub b} was observed for the perpendicular and in-plane anisotropies.

  1. Higher-order anisotropies in the blast-wave model: Disentangling flow and density field anisotropies

    Energy Technology Data Exchange (ETDEWEB)

    Cimerman, Jakub [Czech Technical University in Prague, FNSPE, Prague (Czech Republic); Comenius University, FMPI, Bratislava (Slovakia); Tomasik, Boris [Czech Technical University in Prague, FNSPE, Prague (Czech Republic); Univerzita Mateja Bela, FPV, Banska Bystrica (Slovakia); Csanad, Mate; Loekoes, Sandor [Eoetvoes Lorand University, Budapest (Hungary)

    2017-08-15

    We formulate a generalisation of the blast-wave model which is suitable for the description of higher-order azimuthal anisotropies of the hadron production. The model includes anisotropy in the density profile as well as an anisotropy in the transverse expansion velocity field. We then study how these two kinds of anisotropies influence the single-particle distributions and the correlation radii of two-particle correlation functions. Particularly we focus on the third-order anisotropy and consideration is given averaging over different orientations of the event plane. (orig.)

  2. Interface models

    DEFF Research Database (Denmark)

    Ravn, Anders P.; Staunstrup, Jørgen

    1994-01-01

    This paper proposes a model for specifying interfaces between concurrently executing modules of a computing system. The model does not prescribe a particular type of communication protocol and is aimed at describing interfaces between both software and hardware modules or a combination of the two....... The model describes both functional and timing properties of an interface...

  3. Discontinuous spring magnet-type magnetostrictive Terfecohan/YFeCo multilayers: A novel nanostructured material principle for excellent magnetic softness

    International Nuclear Information System (INIS)

    Duc, N.H.; Huong Giang, D.T.

    2007-01-01

    Novel physics and reversal mechanisms of the whole system switching (WS) and individual switching (IS) type are reported for hard/soft TbFeCo/YFeCo exchange-spring multilayers. The WS type usually occurs in multilayered systems, in which the magnetic anisotropy of hard TbFeCo layers is neglectable. For such a system, the ferrimagnetically coupled hard/soft multilayered state is recovered after removing applied fields from the magnetized state. At low negative fields, the magnetization switching occurs collectively for all magnetic moments in the whole system. In this case, the low-coercivity mechanism is discussed on the basis of a hard/soft interfacial point contact. This configuration is realized for TbFeCo/YFeCo discontinuous exchange-spring multilayers, in which the magnetic (Fe,Co) nanograins coexist with non-magnetic amorphous phase in the soft layers. In this state, a magnetic coercivity as small as 0.4 mT is achieved. It is considered as an excellent magnetic softness of rare-earth-based systems. Enhancing the magnetic anisotropy in the hard TbFeCo layers, the magnetization switching follows the IS type at low temperatures. Starting to decrease the applied magnetic field from the high-field state, one observes the first reversal of the magnetic moments in the soft high-magnetization YFeCo-layers in positive magnetic fields. This is the reason for the observation of the negative coercivity as well as negative-biasing phenomena

  4. EUV multilayer mirror, optical system including a multilayer mirror and method of manufacturing a multilayer mirror

    NARCIS (Netherlands)

    Huang, Qiushi; Louis, Eric; Bijkerk, Frederik; de Boer, Meint J.; von Blanckenhagen, G.

    2016-01-01

    A multilayer mirror (M) reflecting extreme ultraviolet (EUV) radiation from a first wave-length range in a EUV spectral region comprises a substrate (SUB) and a stack of layers (SL) on the substrate, the stack of layers comprising layers comprising a low index material and a high index material, the

  5. Electron density profile in multilayer systems

    International Nuclear Information System (INIS)

    Toekesi, K.

    2004-01-01

    Complete text of publication follows. Electron energy loss spectroscopy (EELS) has been used extensively to study the multilayer systems, where the thickness of layers are in the nanometer range. These studies has received considerable attention because of its technological interest, for example in the nanotechnology. On the most fundamental level, its importance is derived from the basic physics that is involved. One key quantities of interest is the response of a many-body system to an external perturbation: How act and how modify the interface between the solid-solid or solid-vacuum the excitations in the solid and in the vicinity of the interfaces. In this work, as a starting point of such investigations we calculated the electron density profile for multilayer systems. Our approach employs the time-dependent density functional theory (TDDFT), that is, the solution of a time-dependent Schroedinger equation in which the potential and forces are determined selfconsistently from the dynamics governed by the Schroedinger equation. We treat the problem in TDDFT at the level of the local-density approximation (LDA). Later, the comparison of experimentally obtained loss functions and the theory, based on our TDDFT calculations can provide deeper understanding of surface physics. We performed the calculations for half-infinite samples characterized by r s =1.642 and r s =1.997. We also performed the calculations for double layer systems. The substrate was characterized by r s =1.997 and the coverage by r s =1.642. Fig. 1. shows the obtained electron density profile in LDA approximation. Because of the sharp cutoff of electronic wave vectors at the Fermi surface, the densities in the interior exhibit slowly decaying Friedel oscillations. To highlight the Friedel oscillation we enlarged the electron density profile in Fig. 1a. and Fig. 1b. The work was supported by the Hungarian Scientific Research Found: OTKA No. T038016, the grant 'Bolyai' from the Hungarian Academy of

  6. Iontophoretic transdermal drug delivery: a multi-layered approach.

    Science.gov (United States)

    Pontrelli, Giuseppe; Lauricella, Marco; Ferreira, José A; Pena, Gonçalo

    2017-12-11

    We present a multi-layer mathematical model to describe the transdermal drug release from an iontophoretic system. The Nernst-Planck equation describes the basic convection-diffusion process, with the electric potential obtained by solving the Laplace's equation. These equations are complemented with suitable interface and boundary conditions in a multi-domain. The stability of the mathematical problem is discussed in different scenarios and a finite-difference method is used to solve the coupled system. Numerical experiments are included to illustrate the drug dynamics under different conditions. © The authors 2016. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

  7. Mono- and multilayers of molecular spoked carbazole wheels on graphite.

    Science.gov (United States)

    Jester, Stefan-S; Aggarwal, A Vikas; Kalle, Daniel; Höger, Sigurd

    2014-01-01

    Self-assembled monolayers of a molecular spoked wheel (a shape-persistent macrocycle with an intraannular spoke/hub system) and its synthetic precursor are investigated by scanning tunneling microscopy (STM) at the liquid/solid interface of 1-octanoic acid and highly oriented pyrolytic graphite. The submolecularly resolved STM images reveal that the molecules indeed behave as more or less rigid objects of certain sizes and shapes - depending on their chemical structures. In addition, the images provide insight into the multilayer growth of the molecular spoked wheels (MSWs), where the first adlayer acts as a template for the commensurate adsorption of molecules in the second layer.

  8. Mono- and multilayers of molecular spoked carbazole wheels on graphite

    Directory of Open Access Journals (Sweden)

    Stefan-S. Jester

    2014-11-01

    Full Text Available Self-assembled monolayers of a molecular spoked wheel (a shape-persistent macrocycle with an intraannular spoke/hub system and its synthetic precursor are investigated by scanning tunneling microscopy (STM at the liquid/solid interface of 1-octanoic acid and highly oriented pyrolytic graphite. The submolecularly resolved STM images reveal that the molecules indeed behave as more or less rigid objects of certain sizes and shapes – depending on their chemical structures. In addition, the images provide insight into the multilayer growth of the molecular spoked wheels (MSWs, where the first adlayer acts as a template for the commensurate adsorption of molecules in the second layer.

  9. Axisymmetric Vibration of Piezo-Lemv Composite Hollow Multilayer Cylinder

    Directory of Open Access Journals (Sweden)

    E. S. Nehru

    2012-01-01

    Full Text Available Axisymmetric vibration of an infinite piezolaminated multilayer hollow cylinder made of piezoelectric layers of 6 mm class and an isotropic LEMV (Linear Elastic Materials with Voids layers is studied. The frequency equations are obtained for the traction free outer surface with continuity conditions at the interfaces. Numerical results are carried out for the inner, middle, and outer hollow piezoelectric layers bonded by LEMV (It is hypothetical material layers and the dispersion curves are compared with that of a similar 3-layer model and of 3 and 5 layer models with inner, middle, and outer hollow piezoelectric layers bonded by CFRP (Carbon fiber reinforced plastics.

  10. Preparation and analysis of multilayer composites based on polyelectrolyte complexes

    Energy Technology Data Exchange (ETDEWEB)

    Petrova, V. A. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Orekhov, A. S. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation); Chernyakov, D. D. [St. Petersburg State Chemical Pharmaceutical Academy (Russian Federation); Baklagina, Yu. G. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Romanov, D. P. [Russian Academy of Sciences, Grebenshchikov Institute of Silicate Chemistry (Russian Federation); Kononova, S. V. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Volod’ko, A. V.; Ermak, I. M. [Russian Academy of Sciences, Elyakov Pacific Institute of Bioorganic Chemistry, Far-Eastern Branch (Russian Federation); Klechkovskaya, V. V., E-mail: klechvv@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation); Skorik, Yu. A., E-mail: yury-skorik@mail.ru [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation)

    2016-11-15

    A method for preparing multilayer film composites based on chitosan has been developed by the example of polymer pairs: chitosan–hyaluronic acid, chitosan–alginic acid, and chitosan–carrageenan. The structure of the composite films is characterized by X-ray diffractometry and scanning electron microscopy. It is shown that the deposition of a solution of hyaluronic acid, alginic acid, or carrageenan on a chitosan gel film leads to the formation of a polyelectrolyte complex layer at the interface, which is accompanied by the ordering of chitosan chains in the surface region; the microstructure of this layer depends on the nature of contacting polymer pairs.

  11. Influence of keV-He ion bombardment on the magnetic properties of Co/Pd multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Mueglich, Nicolas; Buhl, Oliver; Weis, Tanja; Engel, Dieter; Ehresmann, Arno [Institute of Physics and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel (Germany); Hellwig, Olav [San Jose Research Center, HGST, A Western Digital Company, CA (United States)

    2013-07-01

    Thin films of ferromagnetic Co separated by Pd films with thicknesses in the first ferromagnetic maximum of interlayer exchange coupling are magnetically dominated by perpendicular-to-plane anisotropy and labyrinth stripe domain patterns in remanence. During the magnetization reversal of such a multilayer system domain nucleation and domain wall movement can be observed for different external magnetic fields H. The influence of keV-He ion bombardment on the microstructure of the system and its resultant decrease of magnetic anisotropy has been investigated by vibrating sample magnetometry, polar magneto-optical Kerr effect and magnetic force microscopy. It is shown that areas of ferromagnetic in-plane anisotropy are created due to the ion bombardement and that the system shows an increasing quotient of superparamagnetism in the deeper layers of the multilayersystem.

  12. Evaluation of electrical resistivity anisotropy in geological mapping ...

    African Journals Online (AJOL)

    user

    Key words: Electrical resistivity anisotropy, radial vertical electrical sounding, anisotropy polygons. INTRODUCTION ... electrical resistivity survey in the geological interpretation ... resistivity and other electrical or electromagnetic based.

  13. Preparation and properties of [(NdFeB)x/(Nb)z]n multi-layer films

    International Nuclear Information System (INIS)

    Tsai, J.-L.; Chin, T.-S.; Yao, Y.-D.; Melsheimer, A.; Fisher, S.; Drogen, T.; Kelsch, M.; Kronmueller, H.

    2003-01-01

    Multi-layer [(NdFeB) x /(Nb) z ] n films with 200 nm≥x≥10 nm, 10 nm≥z≥0, 40≥n≥2, prepared by ion beam sputtering and subsequent annealing, show significantly enhanced coercivity due to the reduced grain size that enhances the anisotropy of individual grains. After annealing at 630 deg. C, some Nd 2 Fe 14 B grains were enriched with Nb and isolated as the thickness of the Nb spacer layer increases. For multi-layer (NdFeB x /Nb z ) n films with 100 nm ≥x≥25 nm, 5 nm≥z≥2 nm, their coercivity and remanence ratio are better than that of a single NdFeB film. Up to 17.8 kOe room temperature coercivity has been obtained for a sample with x=25 nm, z=5 nm and n=16

  14. Three-dimensional spin mapping of antiferromagnetic nanopyramids having spatially alternating surface anisotropy at room temperature.

    Science.gov (United States)

    Wang, Kangkang; Smith, Arthur R

    2012-11-14

    Antiferromagnets play a key role in modern spintronic devices owing to their ability to modify the switching behavior of adjacent ferromagnets via the exchange bias effect. Consequently, detailed measurements of the spin structure at antiferromagnetic interfaces and surfaces are highly desirable, not only for advancing technologies but also for enabling new insights into the underlying physics. Here using spin-polarized scanning tunneling microscopy at room-temperature, we reveal in three-dimensions an orthogonal spin structure on antiferromagnetic compound nanopyramids. Contrary to expected uniaxial anisotropy based on bulk properties, the atomic terraces are found to have alternating in-plane and out-of-plane magnetic anisotropies. The observed layer-wise alternation in anisotropy could have strong influences on future nanoscale spintronic applications.

  15. Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

    Directory of Open Access Journals (Sweden)

    H. K. Lee

    2016-05-01

    Full Text Available We report ferromagnetic resonance measurements of magnetic anisotropy and damping in epitaxial La0.7Sr0.3MnO3 (LSMO and Pt capped LSMO thin films on SrTiO3 (001 substrates. The measurements reveal large negative perpendicular magnetic anisotropy and a weaker uniaxial in-plane anisotropy that are unaffected by the Pt cap. The Gilbert damping of the bare LSMO films is found to be low α = 1.9(1 × 10−3, and two-magnon scattering is determined to be significant and strongly anisotropic. The Pt cap increases the damping by 50% due to spin pumping, which is also directly detected via inverse spin Hall effect in Pt. Our work demonstrates efficient spin transport across the Pt/LSMO interface.

  16. Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H. K., E-mail: hankl@uci.edu; Barsukov, I.; Yang, L.; Krivorotov, I. N. [Physics and Astronomy, University of California, Irvine, California 92697 (United States); Swartz, A. G.; Kim, B. [Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Hwang, H. Y. [Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2016-05-15

    We report ferromagnetic resonance measurements of magnetic anisotropy and damping in epitaxial La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) and Pt capped LSMO thin films on SrTiO{sub 3} (001) substrates. The measurements reveal large negative perpendicular magnetic anisotropy and a weaker uniaxial in-plane anisotropy that are unaffected by the Pt cap. The Gilbert damping of the bare LSMO films is found to be low α = 1.9(1) × 10{sup −3}, and two-magnon scattering is determined to be significant and strongly anisotropic. The Pt cap increases the damping by 50% due to spin pumping, which is also directly detected via inverse spin Hall effect in Pt. Our work demonstrates efficient spin transport across the Pt/LSMO interface.

  17. Plasmonic reflectance anisotropy spectroscopy of metal nanoparticles on a semiconductor surface

    Science.gov (United States)

    Kosobukin, V. A.; Korotchenkov, A. V.

    2016-12-01

    A theory of plasmonic differential anisotropic reflection of light from nanoparticles located near the interface between media is developed. The model of a monolayer consisting of identical ellipsoidal metal particles occupying sites of a rectangular lattice is investigated. Effective plasmonic polarizabilities of nanoparticles in the layer are calculated self-consistently using the Green's function technique in the quasipoint dipole approximation. The local-field effect caused by anisotropic dipole plasmons of particles in the layer and their image dipoles is taken into account. The lately observed resonant reflectance anisotropy spectra of indium nanoclusters on InAs surface are explained by the difference between frequencies of plasmons with the orthogonal polarizations in the surface plane. The difference between the plasmon frequencies is attributed to anisotropy of the particles shape or/and the layer structure; the signs of frequency difference for the two types of anisotropy being different.

  18. Primordial anisotropies in gauged hybrid inflation

    Science.gov (United States)

    Akbar Abolhasani, Ali; Emami, Razieh; Firouzjahi, Hassan

    2014-05-01

    We study primordial anisotropies generated in the model of gauged hybrid inflation in which the complex waterfall field is charged under a U(1)gauge field. Primordial anisotropies are generated either actively during inflation or from inhomogeneities modulating the surface of end of inflation during waterfall transition. We present a consistent δN mechanism to calculate the anisotropic power spectrum and bispectrum. We show that the primordial anisotropies generated at the surface of end of inflation do not depend on the number of e-folds and therefore do not produce dangerously large anisotropies associated with the IR modes. Furthermore, one can find the parameter space that the anisotropies generated from the surface of end of inflation cancel the anisotropies generated during inflation, therefore relaxing the constrains on model parameters imposed from IR anisotropies. We also show that the gauge field fluctuations induce a red-tilted power spectrum so the averaged power spectrum from the gauge field can change the total power spectrum from blue to red. Therefore, hybrid inflation, once gauged under a U(1) field, can be consistent with the cosmological observations.

  19. Primordial anisotropies in gauged hybrid inflation

    International Nuclear Information System (INIS)

    Abolhasani, Ali Akbar; Emami, Razieh; Firouzjahi, Hassan

    2014-01-01

    We study primordial anisotropies generated in the model of gauged hybrid inflation in which the complex waterfall field is charged under a U(1)gauge field. Primordial anisotropies are generated either actively during inflation or from inhomogeneities modulating the surface of end of inflation during waterfall transition. We present a consistent δN mechanism to calculate the anisotropic power spectrum and bispectrum. We show that the primordial anisotropies generated at the surface of end of inflation do not depend on the number of e-folds and therefore do not produce dangerously large anisotropies associated with the IR modes. Furthermore, one can find the parameter space that the anisotropies generated from the surface of end of inflation cancel the anisotropies generated during inflation, therefore relaxing the constrains on model parameters imposed from IR anisotropies. We also show that the gauge field fluctuations induce a red-tilted power spectrum so the averaged power spectrum from the gauge field can change the total power spectrum from blue to red. Therefore, hybrid inflation, once gauged under a U(1) field, can be consistent with the cosmological observations

  20. Magnetic bubbles and domain evolution in Fe/Gd multilayer nanodots

    Science.gov (United States)

    Wang, T. T.; Liu, W.; Dai, Z. M.; Zhao, X. T.; Zhao, X. G.; Zhang, Z. D.

    2018-04-01

    The formation of magnetic bubbles and the domain-evolution processes, induced by a perpendicular magnetic field in Fe/Gd multilayer films and nanodots, have been investigated. At room temperature, the stripe domains in a continuous film transform into magnetic bubbles in an external field, while bubbles form spontaneously in nanodots due to the existence of shape anisotropy. When the temperature decreases to 20 K, the enhancement of the perpendicular magnetic anisotropy of the samples results in an increase of the domain size in the continuous film and the magnetization-reversal behavior of each nanodot becomes independent, and most reversed dots do not depend on each other, indicating the magnetic characteristics of a single domain. The present research provides further understanding of the evolution of magnetic bubbles in the Fe/Gd system and suggests their promising applications in patterned recording materials.

  1. Anomalous Nernst Effects of [CoSiB/Pt] Multilayer Films

    OpenAIRE

    Kelekci, O.; Lee, H. N.; Kim, T. W.; Noh, H.

    2013-01-01

    We report a measurement for the anomalous Nernst effects induced by a temperature gradient in [CoSiB/Pt] multilayer films with perpendicular magnetic anisotropy. The Nernst voltage shows a characteristic hysteresis which reflects the magnetization of the film as in the case of the anomalous Hall effects. With a local heating geometry, we also measure the dependence of the anomalous Nernst voltage on the distance d from the heating element. It is roughly proportional to 1/d^1.3, which can be c...

  2. Electric field-controlled magnetization in exchange biased IrMn/Co/PZT multilayers

    International Nuclear Information System (INIS)

    Huong Giang, D T; Duc, N H; Agnus, G; Maroutian, T; Lecoeur, P

    2013-01-01

    Electric-field modulating exchange bias and near 180° deterministic magnetization switching at room temperature are demonstrated in simple antiferromagnetic/ferromagnetic/ferroelectric (AFM/FM/FE) exchange-coupled multiferroic multilayers of IrMn/Co/PZT. A rather large exchange bias field shift up to ΔH ex /H ex = 500% was obtained. This change governs mainly the electric-field strength rather than the applied current. It is explained as being realized through the competition between the electric-field induced uniaxial and unidirectional anisotropies. These results show good prospects for low-power spintronic devices. (paper)

  3. Magnetic properties of Co-based multilayers with layer-alloyed modulations

    Science.gov (United States)

    Poulopoulos, P.; Angelakeris, M.; Niarchos, D.; Krishnan, R.; Porte, M.; Batas, C.; Flevaris, N. K.

    1995-07-01

    Various types of Co-based multilayers such as Pt mCo n, Pt m[CoPt] n, Co m[CoPd] n and Co m[CoPt] n were prepared by e-gun evaporation. Strong perpendicular anisotropy with considerable coercivity of ˜ 1 kOe was found for PtCo samples with thin Co layers. Moreover, the magnetization of Pt m[CoPt] n samples was found to approach that of pure Co and in the case of n > 5 enhancement of 30% or more exhibited. Magnetic properties were found to be strongly influenced by variations of modulation parameters.

  4. Interplay between collective pinning and artificial defects on domain wall propagation in Co/Pt multilayers

    International Nuclear Information System (INIS)

    Rodriguez-Rodriguez, G; Hierro-Rodriguez, A; Perez-Junquera, A; Montenegro, N; Alameda, J M; Velez, M; Menendez, J L; Ravelosona, D

    2010-01-01

    The interplay between collective pinning on intrinsic structural defects and artificial pinning at a patterned hole is studied in magnetic multilayers with perpendicular anisotropy. The pinning strength of a patterned hole is measured through its efficiency to stop domain wall (DW) propagation into a consecutive unpatterned nanowire section (using antisymmetric magnetoresistance to detect the direction of DW propagation) whereas collective pinning is characterized by the field dependence of DW velocity. Close to room temperature, collective pinning becomes weaker than artificial pinning so that pinning at the hole compensates nucleation-pad geometry, blocking DW propagation across the nanowire.

  5. Resistive switching via the converse magnetoelectric effect in ferromagnetic multilayers on ferroelectric substrates.

    Science.gov (United States)

    Pertsev, N A; Kohlstedt, H

    2010-11-26

    A voltage-controlled resistive switching is predicted for ferromagnetic multilayers and spin valves mechanically coupled to a ferroelectric substrate. The switching between low- and high-resistance states results from the strain-driven magnetization reorientations by about 90°, which are shown to occur in ferromagnetic layers with a high magnetostriction and weak cubic magnetocrystalline anisotropy. Such reorientations, not requiring external magnetic fields, can be realized experimentally by applying moderate electric field to a thick substrate (bulk or membrane type) made of a relaxor ferroelectric having ultrahigh piezoelectric coefficients. The proposed multiferroic hybrids exhibiting giant magnetoresistance may be employed as electric-write nonvolatile magnetic memory cells with nondestructive readout.

  6. Thermally induced delamination of multilayers

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Sarraute, S.; Jørgensen, O.

    1998-01-01

    Steady-state delamination of multilayered structures, caused by stresses arising during processing due to thermal expansion mismatch, is analyzed by a fracture mechanics model based on laminate theory. It is found that inserting just a few interlayers with intermediate thermal expansion coefficie...... coefficients may be an effective way of reducing the delamination energy release rate. Uneven layer thickness and increasing elastic mismatch are shown to raise the energy release rate. Experimental work confirms important trends of the model.......Steady-state delamination of multilayered structures, caused by stresses arising during processing due to thermal expansion mismatch, is analyzed by a fracture mechanics model based on laminate theory. It is found that inserting just a few interlayers with intermediate thermal expansion...

  7. Exchange coupling in metallic multilayers with a top FeRh layer

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, S., E-mail: yamada@ee.es.osaka-u.ac.jp; Kanashima, T.; Hamaya, K., E-mail: hamaya@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Tanikawa, K. [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Hirayama, J. [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Taniyama, T. [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2016-05-15

    We study magnetic properties of metallic multilayers with FeRh/ferromagnet interfaces grown by low-temperature molecular beam epitaxy. Room-temperature coercivity of the ferromagnetic layers is significantly enhanced after the growth of FeRh, proving the existence of the exchange coupling between the antiferromagnetic FeRh layer and the ferromagnetic layer. However, exchange bias is not clearly observed probably due to the presence of disordered structures, which result from the lattice strain at the FeRh/ferromagnet interfaces due to the lattice mismatch. We infer that the lattice matched interface between FeRh and ferromagnetic layers is a key parameter for controlling magnetic switching fields in such multilayer systems.

  8. Stress-related interdiffusion in dc sputtered TiN/B endash C endash N multilayers

    International Nuclear Information System (INIS)

    Fayeulle, S.; Nastasi, M.

    1998-01-01

    The diffusion in TiN/B endash C endash N multilayers during vacuum annealing at temperatures up to 1000thinsp degree C and/or 300 keV argon irradiation is studied. Changes in composition, stress field, bilayer repeat length, and interface quality are reported. The effect of stress on diffusion is proved by performing the same annealing or the same irradiation on a multilayer with and without compressive stress. During thermal annealing, demixing or phase separation is observed. On the contrary, during irradiation, mixing occurs. Both phenomena are enhanced in the presence of the stress field. copyright 1998 American Institute of Physics

  9. Modelling migration in multilayer systems by a finite difference method: the spherical symmetry case

    International Nuclear Information System (INIS)

    Hojbota, C I; Toşa, V; Mercea, P V

    2013-01-01

    We present a numerical model based on finite differences to solve the problem of chemical impurity migration within a multilayer spherical system. Migration here means diffusion of chemical species in conditions of concentration partitioning at layer interfaces due to different solubilities of the migrant in different layers. We detail here the numerical model and discuss the results of its implementation. To validate the method we compare it with cases where an analytic solution exists. We also present an application of our model to a practical problem in which we compute the migration of caprolactam from the packaging multilayer foil into the food

  10. Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

    DEFF Research Database (Denmark)

    Windt, D.L.; Christensen, Finn Erland; Craig, W.W.

    2000-01-01

    that the dominant interface imperfection in these films is interfacial diffuseness; interfacial roughness is minimal (sigma(r)similar to 0.175 nm) in structures prepared under optimal conditions, but can increase under conditions in which the beneficial effects of energetic bombardment during growth are compromised......-graded W/Si multilayer structures, and high-resolution transmission electron microscopy (TEM) and selected area electron diffraction (SAED) to characterize the interface structure and layer morphology as a function of depth in an optimized depth-graded multilayer. From x-ray analysis we find interface......), and somewhat larger interface widths (i.e., sigma=0.35-0.4 nm) for structures grown at higher Ar pressures, higher background pressures, or with larger target-to-substrate distances. We find no variation in interface widths with magnetron power. Nonspecular x-ray reflectance analysis and TEM suggest...

  11. CLASSICAL AREAS OF PHENOMENOLOGY: First-principles calculations for the elastic properties of Ni-base model superalloys: Ni/Ni3Al multilayers

    Science.gov (United States)

    Wang, Yun-Jiang; Wang, Chong-Yu

    2009-10-01

    A model system consisting of Ni[001](100)/Ni3Al[001](100) multi-layers are studied using the density functional theory in order to explore the elastic properties of single crystal Ni-based superalloys. Simulation results are consistent with the experimental observation that rafted Ni-base superalloys virtually possess a cubic symmetry. The convergence of the elastic properties with respect to the thickness of the multilayers are tested by a series of multilayers from 2γ'+2γ to 10γ'+10γ atomic layers. The elastic properties are found to vary little with the increase of the multilayer's thickness. A Ni/Ni3Al multilayer with 10γ'+10γ atomic layers (3.54 nm) can be used to simulate the mechanical properties of Ni-base model superalloys. Our calculated elastic constants, bulk modulus, orientation-dependent shear modulus and Young's modulus, as well as the Zener anisotropy factor are all compatible with the measured results of Ni-base model superalloys R1 and the advanced commercial superalloys TMS-26, CMSX-4 at a low temperature. The mechanical properties as a function of the γ' phase volume fraction are calculated by varying the proportion of the γ and γ' phase in the multilayers. Besides, the mechanical properties of two-phase Ni/Ni3Al multilayer can be well predicted by the Voigt-Reuss-Hill rule of mixtures.

  12. A perturbative DFT approach for magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Khoo, Khoong Hong; Laskowski, Robert, E-mail: rolask@ihpc.a-star.edu.sg

    2017-04-15

    We develop a perturbative formalism for computing magnetocrystalline anisotropy within density functional theory and the magnetic force theorem. Instead of computing eigenvalues of the spin–orbit Hamiltonian for selected spin polarizations, as in the conventional “force theorem” approach, we show that the effect can be cast into a redefined form of the spin–orbit operator. This allows to separate the large eigenvalue shift due to spin-orbit interaction common for both polarizations from the much smaller magnetic anisotropy splitting. As a consequence the anisotropy splitting may by considered as a perturbation.

  13. Mathematical Formulation of Multilayer Networks

    Science.gov (United States)

    De Domenico, Manlio; Solé-Ribalta, Albert; Cozzo, Emanuele; Kivelä, Mikko; Moreno, Yamir; Porter, Mason A.; Gómez, Sergio; Arenas, Alex

    2013-10-01

    A network representation is useful for describing the structure of a large variety of complex systems. However, most real and engineered systems have multiple subsystems and layers of connectivity, and the data produced by such systems are very rich. Achieving a deep understanding of such systems necessitates generalizing “traditional” network theory, and the newfound deluge of data now makes it possible to test increasingly general frameworks for the study of networks. In particular, although adjacency matrices are useful to describe traditional single-layer networks, such a representation is insufficient for the analysis and description of multiplex and time-dependent networks. One must therefore develop a more general mathematical framework to cope with the challenges posed by multilayer complex systems. In this paper, we introduce a tensorial framework to study multilayer networks, and we discuss the generalization of several important network descriptors and dynamical processes—including degree centrality, clustering coefficients, eigenvector centrality, modularity, von Neumann entropy, and diffusion—for this framework. We examine the impact of different choices in constructing these generalizations, and we illustrate how to obtain known results for the special cases of single-layer and multiplex networks. Our tensorial approach will be helpful for tackling pressing problems in multilayer complex systems, such as inferring who is influencing whom (and by which media) in multichannel social networks and developing routing techniques for multimodal transportation systems.

  14. Mo/Si multilayers with enhanced TiO II- and RuO II-capping layers

    Science.gov (United States)

    Yulin, Sergiy; Benoit, Nicolas; Feigl, Torsten; Kaiser, Norbert; Fang, Ming; Chandhok, Manish

    2008-03-01

    The lifetime of Mo/Si multilayer-coated projection optics is one of the outstanding issues on the road of commercialization of extreme-ultraviolet lithography (EUVL). The application of Mo/Si multilayer optics in EUVL requires both sufficient radiation stability and also the highest possible normal-incidence reflectivity. A serious problem of conventional high-reflective Mo/Si multilayers capped by silicon is the considerable degradation of reflective properties due to carbonization and oxidation of the silicon surface layer under exposure by EUV radiation. In this study, we focus on titanium dioxide (TiO II) and ruthenium dioxide (RuO II) as promising capping layer materials for EUVL multilayer coatings. The multilayer designs as well as the deposition parameters of the Mo/Si systems with different capping layers were optimized in terms of maximum peak reflectivity at the wavelength of 13.5 nm and longterm stability under high-intensive irradiation. Optimized TiO II-capped Mo/Si multilayer mirrors with an initial reflectivity of 67.0% presented a reflectivity drop of 0.6% after an irradiation dose of 760 J/mm2. The reflectivity drop was explained by the partial oxidation of the silicon sub-layer. No reflectivity loss after similar irradiation dose was found for RuO II-capped Mo/Si multilayer mirrors having initial peak reflectivity of 66%. In this paper we present data on improved reflectivity of interface-engineered TiO II- and RuO II-capped Mo/Si multilayer mirrors due to the minimization of both interdiffusion processes inside the multilayer stack and absorption loss in the oxide layer. Reflectivities of 68.5% at the wavelength of 13.4 nm were achieved for both TiO II- and RuO II-capped Mo/Si multilayer mirrors.

  15. Study of interfaces in organic semiconductor heterojunctions

    International Nuclear Information System (INIS)

    Maheshwari, P; Dutta, D; Sudarshan, K; Sharma, S K; Pujari, P K; Samanta, S; Singh, A; Aswal, D K

    2011-01-01

    The defect structure at the organic heterojunctions is studied using slow positron beam. The structural and electronic properties of heterojunctions are of technological and fundamental importance for understanding and optimization of electronic processes in organic devices. Interface trap centres play a significant role in the electrical conduction through the junctions. Depth dependent Doppler broadened annihilation measurements have been carried out in p- and n-type organic semiconductor thin films (30-80 nm) both single as well as multilayers grown on quartz substrate. The objective of the present study is to investigate the defect structure and to understand the behavior of positrons at the charged organic interfaces. Our result shows the sensitivity of positrons to the interfacial disorders that may be a convoluted effect of the presence of defects as well as the influence of the charge dipole in multilayers.

  16. Solvent induced supramolecular anisotropy in molecular gels

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Michael A., E-mail: mroger09@uoguelph.ca [Department of Food Science, University of Guelph, Guelph, Ontario, N3C3X9 (Canada); Corradini, Maria G. [Department of Food Science, University of Massachusetts Amherst, Amherst, MA, 01003 (United States); Emge, Thomas [Department of Chemistry and Biochemistry, Rutgers University, New Brunswick, NJ, 08901 (United States)

    2017-06-15

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  17. Solvent induced supramolecular anisotropy in molecular gels

    International Nuclear Information System (INIS)

    Rogers, Michael A.; Corradini, Maria G.; Emge, Thomas

    2017-01-01

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  18. Texture and anisotropy analysis of Qusaiba shales

    KAUST Repository

    Kanitpanyacharoen, Waruntorn; Wenk, Hans-Rudolf; Kets, Frans; Lehr, Christian; Wirth, Richard

    2011-01-01

    Scanning and transmission electron microscopy, synchrotron X-ray diffraction, microtomography and ultrasonic velocity measurements were used to characterize microstructures and anisotropy of three deeply buried Qusaiba shales from the Rub

  19. Cellulose and the Control of Growth Anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Tobias I. Baskin

    2004-04-01

    The authors research aims to understand morphogenesis, focusing on growth anisotropy, a process that is crucial to make organs with specific and heritable shapes. For the award, the specific aims were to test hypotheses concerning how growth anisotropy is controlled by cell wall structure, particularly by the synthesis and alignment of cellulose microfibrils, the predominant mechanical element in the cell wall. This research has involved characterizing the basic physiology of anisotropic expansion, including measuring it at high resolution; and second, characterizing the relationship between growth anisotropy, and cellulose microfibrils. Important in this relationship and also to the control of anisotropic expansion are structures just inside the plasma membrane called cortical microtubules, and the research has also investigated their contribution to controlling anisotropy and microfibril alignment. In addition to primary experimental papers, I have also developed improved methods relating to these objectives as well as written relevant reviews. Major accomplishments in each area will now be described.

  20. Mechanical and tribological properties of a-C/a-C:Ti multilayer films with various bilayer periods

    Energy Technology Data Exchange (ETDEWEB)

    Bai, W.Q.; Cai, J.B.; Wang, X.L., E-mail: wangxl@zju.edu.cn; Wang, D.H.; Gu, C.D.; Tu, J.P., E-mail: tujp@zju.edu.cn

    2014-05-02

    Thick a-C/a-C:Ti multilayer films with bilayer periods of 12–70 nm were deposited on Ti6Al4V alloy substrate by means of closed field unbalance magnetron sputtering. The morphology and microstructure of the multilayer films were investigated by scanning electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Nanocrystalline TiC was distributed in the a-C:Ti layer and at the interface between the two adjacent layers. The mechanical and tribological properties were evaluated by Rockwell and scratch tests, a nanoindentor and a ball-on-disk tribometer. The multilayer film with a bilayer period of 12 nm showed the highest adhesion strength, hardness (26 GPa) and elastic modulus (232 GPa); it also had the lowest average coefficient of friction (0.09) and a wear rate of 8.06 × 10{sup −17} m{sup 3} N{sup −1} m{sup −1}. - Highlights: • a-C/a-C:Ti multilayers with various bilayer periods were prepared. • Nanocrystalline TiCs were confirmed in the a-C:Ti layer and at the interface. • These multilayers show fine ability to comply with substrate deformation. • The multilayer with a bilayer period of 12 nm exhibits the best properties.

  1. Magnetoresistive multilayers deposited on the AAO membranes

    International Nuclear Information System (INIS)

    Malkinski, Leszek M.; Chalastaras, Athanasios; Vovk, Andriy; Jung, Jin-Seung; Kim, Eun-Mee; Jun, Jong-Ho; Ventrice, Carl A.

    2005-01-01

    Silicon and GaAs wafers are the most commonly used substrates for deposition of giant magnetoresistive (GMR) multilayers. We explored a new type of a substrate, prepared electrochemically by anodization of aluminum sheets, for deposition of GMR multilayers. The surface of this AAO substrate consists of nanosized hemispheres organized in a regular hexagonal array. The current applied along the substrate surface intersects many magnetic layers in the multilayered structure, which results in enhancement of giant magnetoresistance effect. The GMR effect in uncoupled Co/Cu multilayers was significantly larger than the magnetoresistance of similar structures deposited on Si

  2. Higher-order anisotropies in the Buda-Lund model: Disentangling flow and density field anisotropies

    Energy Technology Data Exchange (ETDEWEB)

    Loekoes, Sandor [Eoetvoes Lorand University, Budapest (Hungary); Csanad, Mate [Eoetvoes Lorand University, Budapest (Hungary); Stony Brook University, Stony Brook, NY (United States); Tomasik, Boris [Univerzita Mateja Bela, Banska Bystrica (Slovakia); Czech Technical University in Prague, FNSPE, Prague (Czech Republic); Csoergo, Tamas [Wigner RCP, Budapest (Hungary); KRF, Gyoengyoes (Hungary)

    2016-10-15

    The Buda-Lund hydro model describes an expanding ellipsoidal fireball, and fits the observed elliptic flow and oscillating HBT radii successfully. Due to fluctuations in energy depositions, the fireball shape however fluctuates on an event-by-event basis. The transverse plane asymmetry can be translated into a series of multipole anisotropy coefficients. These anisotropies then result in measurable momentum-space anisotropies, to be measured with respect to their respective symmetry planes. In this paper we detail an extension of the Buda-Lund model to multipole anisotropies and investigate the resulting flow coefficients and oscillations of HBT radii. (orig.)

  3. Organic interfaces

    NARCIS (Netherlands)

    Poelman, W.A.; Tempelman, E.

    2014-01-01

    This paper deals with the consequences for product designers resulting from the replacement of traditional interfaces by responsive materials. Part 1 presents a theoretical framework regarding a new paradigm for man-machine interfacing. Part 2 provides an analysis of the opportunities offered by new

  4. Interface Realisms

    DEFF Research Database (Denmark)

    Pold, Søren

    2005-01-01

    This article argues for seeing the interface as an important representational and aesthetic form with implications for postmodern culture and digital aesthetics. The interface emphasizes realism due in part to the desire for transparency in Human-Computer Interaction (HCI) and partly...

  5. Slow electron contribution to inelastic reflection anisotropy

    International Nuclear Information System (INIS)

    Podsvirov, O.A.; Kuznetsov, Yu.A.

    1980-01-01

    Investigated is electron contribution with low energy (up to 1 keV) to the anisotropy of electron inelastic reflection (IRE) from silicon monocrystal (111) within 12-50 keV energy range of primary electrons. Experimental data on IRE anisotropy are presented: delay curves for silicon monocrystal, permitting to separate electrons with the energy up to 1 keV, dependences of IRE anisotropy on the energy of primary electrons for the systems - monocrystalline silicon-amorphous silicon film and delay curves for such systems (film thickness varies from 20 to 2000 A). Suggested is a phenomenologic model, permitting to take into account the contribution of slow electrons to IRE anisotropy: it is supposed, that three groups of electrons take part in the formation of the latter: elastic and inelastic reflected electrons, slow electrons, excited by primary electrons and slow electrons, generated by the reverse flow of the scattered electrons. Contribution of electrons, different by origin, to IRE anisotropy is evaluated in accordance with the experimental data on the basis of this model. It is stated, that slow electrons constitute approximately one half of the IRE anisotropy value, the contribution of both groups of slow electrons being approximately equal

  6. Morphology of the asymmetric iron–silicon interfaces

    International Nuclear Information System (INIS)

    Badía-Romano, L.; Rubín, J.; Bartolomé, F.; Magén, C.; Bartolomé, J.

    2015-01-01

    Highlights: • Exhaustive study of the Fe silicide formation at interfaces of (Fe/Si) multilayers. • Thickness = 1.4 nm and roughness = 0.6 nm are found for the Si-on-Fe interface. • First time that the Fe 1s HAXPES spectra of a multilayered system is recorded. • The c-Fe 1−x Si sublayer is identical in both Si-on-Fe and Fe-on-Si interfaces. • The asymmetry is caused only by the ferromagnetic silicide Fe 1−x Si x sublayer. - Abstract: A systematic study of the iron–silicon interfaces formed upon preparation of (Fe/Si) multilayers has been performed by combination of modern and powerful techniques. Samples were prepared by thermal evaporation under ultrahigh vacuum onto a Si(1 0 0) substrate. The morphology of these films and their interfaces was studied by a combination of scanning transmission electron microscopy, X-ray reflectivity, angle resolved X-ray photoelectron spectroscopy and hard X-ray photoelectron spectroscopy. The Si-on-Fe interface thickness and roughness were determined to be 1.4(1) nm and 0.6(1) nm, respectively. Moreover, determination of the stable phases formed at both Fe-on-Si and Si-on-Fe interfaces was performed using conversion electron Mössbauer spectroscopy on multilayers with well separated Si-on-Fe and Fe-on-Si interfaces. It is shown that while a fraction of Fe remains as α-Fe, the rest has reacted with Si, forming the paramagnetic c-Fe 1−x Si phase and a ferromagnetic Fe rich silicide (DO 3 type phase). We conclude that the paramagnetic c-Fe 1−x Si silicide sublayer is identical in both Si-on-Fe and Fe-on-Si interfaces, whereas an asymmetry is revealed in the composition of the ferromagnetic silicide sublayer

  7. Anomalous Hall effect assisted by interfacial chemical reaction in perpendicular Co/Pt multilayers

    Science.gov (United States)

    Liu, Qian; Jiang, Shaolong; Teng, Jiao

    2018-05-01

    To uncover the underlying mechanism of Mg effect on the improved anomalous Hall effect (AHE) of perpendicular [Pt/Co]3/Mg/HfO2 multilayers, the X-ray photoelectron spectroscopy analysis has been carried out. It is found that Mg interlayer at the Co/HfO2 interface could prevent the Co oxidation to some extent via interfacial chemical reaction. As a result, A large anomalous Hall resistivity (ρAH) is obtained in perpendicular [Pt/Co]3/Mg/HfO2 multilayers, with a maximum ρAH of 3.02 μΩ cm, which is 59% larger than that in Co/Pt multilayers without Mg insertion. This effective modification of the AHE based on interfacial chemical reaction provides a promising pathway for spintronic applications.

  8. Design of grazing-incidence multilayer supermirrors for hard-X-ray reflectors

    DEFF Research Database (Denmark)

    Joensen, K. D.; Voutov, P.; Szentgyorgyi, A.

    1995-01-01

    Extremely broadband grazing-incidence multilayers for hard-X-ray reflection can be obtained by a gradual change of the layer thicknesses down through the structure. Existing approaches for designing similar neutron optics, called supermirrors, are shown to provide respectable performance when...... applied to X-ray multilayers. However, none of these approaches consider the effects of imperfect layer interfaces and absorption in the overlying layers. Adaptations of neutron designs that take these effects into account are presented, and a thorough analysis of two specific applications (a single hard......-X-ray reflector and a hard-X-ray telescope) shows that an improved performance can be obtained. A multilayer whose bilayer thicknesses are given by a power law expression is found to provide the best solution; however, it is only slightly better than some of the adapted neutron designs...

  9. A Method to Estimate the Dynamic Displacement and Stress of a Multi-layered Pavement with Bituminous or Concrete Materials

    Directory of Open Access Journals (Sweden)

    Zheng LU

    2014-12-01

    Full Text Available In this research work, a method to estimate the dynamic characteristics of a multilayered pavement with bituminous or concrete materials is proposed. A mechanical model is established to investigate the dynamic displacement and stress of the multi-layered pavement structure. Both the flexible and the rigid pavements, corresponding to bituminous materials and concrete materials, respectively, are studied. The theoretical solutions of the multi-layered pavement structure are deduced considering the compatibility condition at the interface of the structural layers. By introducing FFT (Fast Fourier Transform algorithm, some numerical results are presented. Comparisons of the theoretical and experimental result implied that the proposed method is reasonable in predicting the stress and displacement of a multi-layered pavement with bituminous or concrete materials. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6071

  10. Modelling of planar interface elastic behaviour: Application to grain boundaries in polycrystals

    International Nuclear Information System (INIS)

    Gelebart, L.

    2010-01-01

    In polycrystalline elastic simulations, grain boundaries can be considered as volume inter-phases or as elastic interfaces assuming a displacement jump across the interface. Such an interface description does not account for the in-plane deformation of the interface and Poisson effects cannot be reproduced. The purpose of this Note is to provide an enriched description of the elastic interface which takes into account such effects. When considering a multilayer material, the interphase description and the enriched interface description yield identical homogenized behaviour while quite important discrepancies can be observed with the classical interface description. (author)

  11. Construction of covalently attached enzyme multilayer films based on the photoreaction of diazo-resins and glucose oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Suxia [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 119 Jie Fang Road, Changchun 130023 (China); Niu Yaming [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 119 Jie Fang Road, Changchun 130023 (China); Sun Changqing [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 119 Jie Fang Road, Changchun 130023 (China)]. E-mail: sunchq@mail.jlu.edu.cn

    2004-10-15

    A novel and facile approach to construct multilayered glucose oxidase (GOx) films on the surface of quartz or CaF{sub 2} slides as well as gold electrodes for use as biosensing interfaces is described. Diazo-resins (DAR) as polycation and glucose oxidase as polyanion were alternately deposited into a multilayer structure using layer-by-layer self-assembly technique based on electrostatic interaction as driving force. Upon near UV irradiation, the adjacent interfaces of the multilayer reacted to form a crosslinking structure which greatly improved the stability of the enzyme films. These changes was monitored and confirmed by UV-vis and IR spectroscopy. Ellipsometric measurements reveal that the enzymes formed sub-molecule layers, and the thickness of the film shows a linear relationship with the number of assembled layers, demonstrating a spatially well-ordered manner in multilayer structure. The covalently attached enzyme multilayer film has a highly permeable structure, and can be used as biosensing interface. Electrochemical and analytical behavior of the enzyme electrodes was studied by cyclic voltammetry (CV) in the presence or absence of glucose. The sensitivity of the enzyme-modified electrodes was estimated through the analysis of voltammetric signals, which can be fine turned to the desired level by adjusting the number of attached bilayers.

  12. Construction of covalently attached enzyme multilayer films based on the photoreaction of diazo-resins and glucose oxidase

    International Nuclear Information System (INIS)

    Zhang Suxia; Niu Yaming; Sun Changqing

    2004-01-01

    A novel and facile approach to construct multilayered glucose oxidase (GOx) films on the surface of quartz or CaF 2 slides as well as gold electrodes for use as biosensing interfaces is described. Diazo-resins (DAR) as polycation and glucose oxidase as polyanion were alternately deposited into a multilayer structure using layer-by-layer self-assembly technique based on electrostatic interaction as driving force. Upon near UV irradiation, the adjacent interfaces of the multilayer reacted to form a crosslinking structure which greatly improved the stability of the enzyme films. These changes was monitored and confirmed by UV-vis and IR spectroscopy. Ellipsometric measurements reveal that the enzymes formed sub-molecule layers, and the thickness of the film shows a linear relationship with the number of assembled layers, demonstrating a spatially well-ordered manner in multilayer structure. The covalently attached enzyme multilayer film has a highly permeable structure, and can be used as biosensing interface. Electrochemical and analytical behavior of the enzyme electrodes was studied by cyclic voltammetry (CV) in the presence or absence of glucose. The sensitivity of the enzyme-modified electrodes was estimated through the analysis of voltammetric signals, which can be fine turned to the desired level by adjusting the number of attached bilayers

  13. The study on the electrical resistivity of Cu/V multilayer films subjected to helium (He) ion irradiation

    Science.gov (United States)

    Wang, P. P.; Xu, C.; Fu, E. G.; Du, J. L.; Gao, Y.; Wang, X. J.; Qiu, Y. H.

    2018-05-01

    Sputtering-deposited Cu/V multilayer films with the individual layer thickness varying from 2.5 nm to 100 nm were irradiated by 1 MeV helium (He) ion at the fluence of 6 ×1016 ions ·cm-2 at room temperature. The resistivity of Cu/V multilayer films after ion irradiation was evaluated as a function of individual layer thickness at 300 K and compared with their resistivity before ion irradiation. The results show that the resistivity change before and after ion irradiation is largely determined by the interface structure, grain boundary and radiation induced defects. A model amended based on the model used in describing the resistivity of as-deposited Cu/V multilayer films was proposed to describe the resistivity of ion irradiated Cu/V multilayer films by considering the point defects induced by ion irradiation, the effect of interface absorption on defects and the effect of interface microstructure in the multilayer films.

  14. Influence of domain structure induced coupling on magnetization reversal of Co/Pt/Co film with perpendicular anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Matczak, Michał [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Schäfer, Rudolf [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Metallic Materials, PO 270116, D-01171 Dresden (Germany); Dresden University of Technology, Institute for Materials Science, D-01062 Dresden (Germany); Urbaniak, Maciej; Kuświk, Piotr; Szymański, Bogdan; Schmidt, Marek; Aleksiejew, Jacek [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Stobiecki, Feliks, E-mail: Feliks.Stobiecki@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

    2017-01-15

    A magnetic multilayer of substrate/Pt-15 nm/Co-0.8 nm/Pt-wedge 0–7 nm/Co-0.6 nm/Pt-2 nm structure is characterized by a perpendicular anisotropy of the Co layers and by graded interlayer coupling between them. Using magnetooptical Kerr microscopy we observed a distinct influence of magnetic domains in one Co layer on the nucleation field and positions of nucleation sites of reversed domains in the second Co layer. For sufficiently strong interlayer coupling a replication of magnetic domains from the magnetically harder layer to the magnetically softer layer is observed. - Highlights: • Co/Pt-wedge/Co layered film is characterized by a gradient of interlayer coupling. • Magnetic field controls propagation of straight domain wall. • Replication of magnetic domains in multilayers with strong ferromagnetic coupling. • Coupling induced by domains influences magnetization reversal of spin valves.

  15. Bioinspired design of dental multilayers.

    Science.gov (United States)

    Huang, M; Wang, R; Thompson, V; Rekow, D; Soboyejo, W O

    2007-01-01

    This paper considers the use of bioinspired functionally graded structures in the design of dental multi-layers that are more resistant to sub-surface crack nucleation. Unlike existing dental crown restorations that give rise to high stress concentration, the functionally graded layers (between crown materials and the joins that attach them to dentin) are shown to promote significant reductions in stress and improvements in the critical crack size. Special inspiration is drawn from the low stress concentrations associated with the graded distributions in the dentin-enamel-junction (DEJ). The implications of such functionally graded structures are also discussed for the design of dental restorations.

  16. Multi-Layer Traffic Steering

    DEFF Research Database (Denmark)

    Fotiadis, Panagiotis; Polignano, Michele; Gimenez, Lucas Chavarria

    2013-01-01

    This paper investigates the potentials of traffic steering in the Radio Resource Control (RRC) Idle state by evaluating the Absolute Priorities (AP) framework in a multilayer Long Term Evolution (LTE) macrocell scenario. Frequency priorities are broadcast on the system information and RRC Idle...... periods are not significantly long. Finally, better alignment between the RRC Connected and Idle mobility procedures is observed, guarantying significant decrease of handovers/reselections and potential battery life savings by minimizing the Inter-Frequency (IF) measurement rate in the RRC Idle....

  17. Superconductivity: a quasiclassical theory of multiple interface geometry

    International Nuclear Information System (INIS)

    Rameshwar, Rudra; Prashant, Sagar; Prasad, Jagdish

    2005-01-01

    In many cases of interests such as a multilayer mesoscopic structure or the grain boundaries network in high technologies, one deal with the situation where multiple interfaces should be treated simultaneously on equal footing. In this paper we have focused on theoretically concept, i.e. even an isolated interface poses certain difficulties. Since abrupt changes violate the quasiclassical condition, the standard theory of superconductivity in terms of the quasiclassical matrix Green function g R is invalid at interfaces. The interface is included via the boundary condition derived by Zaitsev a cubic matrix relation in superconductivity. (author)

  18. Basic research needs and opportunities on interfaces in solar materials

    Energy Technology Data Exchange (ETDEWEB)

    Czanderna, A. W.; Gottschall, R. J. [eds.

    1981-04-01

    The workshop on research needs and recommended research programs on interfaces in solar energy conversion devices was held June 30-July 3, 1980. The papers deal mainly with solid-solid, solid-liquid, and solid-gas interfaces, sometimes involving multilayer solid-solid interfaces. They deal mainly with instrumental techniques of studying these interfaces so they can be optimized, so they can be fabricated with quality control and so changes with time can be forecast. The latter is required because a long lifetime (20 yrs is suggested) is necessary for economic reasons. Fifteen papers have been entered individually into EDB and ERA. (LTN)

  19. Microprocessor interfacing

    CERN Document Server

    Vears, R E

    2014-01-01

    Microprocessor Interfacing provides the coverage of the Business and Technician Education Council level NIII unit in Microprocessor Interfacing (syllabus U86/335). Composed of seven chapters, the book explains the foundation in microprocessor interfacing techniques in hardware and software that can be used for problem identification and solving. The book focuses on the 6502, Z80, and 6800/02 microprocessor families. The technique starts with signal conditioning, filtering, and cleaning before the signal can be processed. The signal conversion, from analog to digital or vice versa, is expl

  20. High reflectance Cr/C multilayer at 250 eV for soft X-ray polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Mingwu; Jiang, Li; Zhang, Zhong; Huang, Qiushi [MOE Key Laboratory of Advanced Micro-Structured Materials, Institute of Precision Optical Engineering (IPOE), School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Wang, Zhanshan, E-mail: wangzs@tongji.edu.cn [MOE Key Laboratory of Advanced Micro-Structured Materials, Institute of Precision Optical Engineering (IPOE), School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); She, Rui; Feng, Hua [Department of Engineering Physics, Tsinghua University, Beijing (China); Wang, Hongchang [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2015-10-01

    X-ray reflection near 45° via multilayer mirrors can be used for astronomical polarization measurements. A Cr/C multilayer mirror (designed for X-ray polarimetry at 250 eV), with a period thickness of 3.86 nm and a bi-layer number of 100, was fabricated using direct current magnetron sputtering. Grazing incidence X-ray reflectometry at 8 keV and transmission electron microscopy were used to investigate the multilayer structure. Different models were introduced to fit the hard X-ray reflectivity curve, which indicates that the layer thickness of two materials slightly drifts from the bottom to the top of the stack. Both the chromium and carbon layers are amorphous with asymmetric interfaces, while the Cr-on-C interface is slightly wider. Based on the good quality of the multilayer structure, a high reflectivity of 21.8% for the s-polarized light was obtained at 250 eV at a grazing incidence angle of 40.7°. The fabricated Cr/C multilayer mirror exhibits high reflectivity and polarization levels in the energy region of 240 eV–260 eV. - Highlights: • We fabricated Cr/C multilayer with 3.8 nm d-spacing. • X-ray reflectometry was used to determine the exact structure of Cr/C multilayer. • A high reflectivity of 21.8% for the s-polarized light was obtained at 250 eV. • Both Cr and C were found to be amorphous with slightly asymmetric interfaces. • A 4-layer model was used to fit and explain the results.

  1. Robust giant magnetoresistive effect type multilayer sensor

    NARCIS (Netherlands)

    Lenssen, K.M.H.; Kuiper, A.E.T.; Roozeboom, F.

    2002-01-01

    A robust Giant Magneto Resistive effect type multilayer sensor comprising a free and a pinned ferromagnetic layer, which can withstand high temperatures and strong magnetic fields as required in automotive applications. The GMR multi-layer has an asymmetric magneto-resistive curve and enables

  2. Multi-Layer E-Textile Circuits

    Science.gov (United States)

    Dunne, Lucy E.; Bibeau, Kaila; Mulligan, Lucie; Frith, Ashton; Simon, Cory

    2012-01-01

    Stitched e-textile circuits facilitate wearable, flexible, comfortable wearable technology. However, while stitched methods of e-textile circuits are common, multi-layer circuit creation remains a challenge. Here, we present methods of stitched multi-layer circuit creation using accessible tools and techniques.

  3. Multilayer Graphene for Waveguide Terahertz Modulator

    DEFF Research Database (Denmark)

    Khromova, I.; Andryieuski, Andrei; Lavrinenko, Andrei

    2014-01-01

    We study terahertz to infrared electromagnetic properties of multilayer graphene/dielectric artificial medium and present a novel concept of terahertz modulation at midinfrared wavelengths. This approach allows the realization of high-speed electrically controllable terahertz modulators based...... on hollow waveguide sections filled with multilayer graphene....

  4. Anisotropies in the cosmic neutrino background after Wilkinson Microwave Anisotropy Probe five-year data

    International Nuclear Information System (INIS)

    De Bernardis, Francesco; Pagano, Luca; Melchiorri, Alessandro; Serra, Paolo; Cooray, Asantha

    2008-01-01

    We search for the presence of cosmological neutrino background (CNB) anisotropies in recent Wilkinson Microwave Anisotropy Probe (WMAP) five-year data using their signature imprinted on modifications to the cosmic microwave background (CMB) anisotropy power spectrum. By parameterizing the neutrino background anisotropies with the speed viscosity parameter c vis , we find that the WMAP five-year data alone provide only a weak indication for CNB anisotropies with c vis 2 >0.06 at the 95% confidence level. When we combine CMB anisotropy data with measurements of galaxy clustering, the SN-Ia Hubble diagram, and other cosmological information, the detection increases to c vis 2 >0.16 at the same 95% confidence level. Future data from Planck, combined with a weak lensing survey such as the one expected with DUNE from space, will be able to measure the CNB anisotropy parameter at about 10% accuracy. We discuss the degeneracy between neutrino background anisotropies and other cosmological parameters such as the number of effective neutrinos species and the dark energy equation of state

  5. Interfacial pattern changes of imprinted multilayered material in milli- and microscales

    Science.gov (United States)

    Yonekura, Kazuhiro; Tokumaru, Kazuki; Tsumori, Fujio

    2018-06-01

    Nanoimprint lithography (NIL) is a technique that transfers a mold pattern of nanometer order to the surface of a resist material by heating and pressing. NIL is an excellent technology in terms of high productivity, accuracy, and resolution. Recently, NIL has been applied to the processing of different multilayered materials, in which it is possible to process multiple materials simultaneously. In this processing of multilayered materials, it is possible to form an interfacial pattern between the upper layer and the lower layer simultaneously with patterning on the mold surface. This interface pattern can be controlled by the deformation characteristics, initial thickness, and so forth. In this research, we compared the interfacial pattern changes of imprinted multilayered materials in milli- and microscales. For multilayered imprint using multiple materials, it is important to know the flow of the resist and its dependence on the scale. If there is similarity in the relationship produced by the scale on the imprinted samples, a process design with a number of feedbacks could be realized. It also becomes easier to treat structures in the millimeter scale for the experiment. In this study, we employed micropowder imprint (µPI) for multilayered material imprint. A compound sheet of alumina powder and polymer binder was used for imprint. Two similar experiments in different scales, micro- and millimeter scales, were carried out. Results indicate that the interfacial patterns of micro- and millimeter-scale-imprinted samples are similar.

  6. Realistic absorption coefficient of each individual film in a multilayer architecture

    Science.gov (United States)

    Cesaria, M.; Caricato, A. P.; Martino, M.

    2015-02-01

    A spectrophotometric strategy, termed multilayer-method (ML-method), is presented and discussed to realistically calculate the absorption coefficient of each individual layer embedded in multilayer architectures without reverse engineering, numerical refinements and assumptions about the layer homogeneity and thickness. The strategy extends in a non-straightforward way a consolidated route, already published by the authors and here termed basic-method, able to accurately characterize an absorbing film covering transparent substrates. The ML-method inherently accounts for non-measurable contribution of the interfaces (including multiple reflections), describes the specific film structure as determined by the multilayer architecture and used deposition approach and parameters, exploits simple mathematics, and has wide range of applicability (high-to-weak absorption regions, thick-to-ultrathin films). Reliability tests are performed on films and multilayers based on a well-known material (indium tin oxide) by deliberately changing the film structural quality through doping, thickness-tuning and underlying supporting-film. Results are found consistent with information obtained by standard (optical and structural) analysis, the basic-method and band gap values reported in the literature. The discussed example-applications demonstrate the ability of the ML-method to overcome the drawbacks commonly limiting an accurate description of multilayer architectures.

  7. Induced spin-polarization of EuS at room temperature in Ni/EuS multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Poulopoulos, P., E-mail: poulop@upatras.gr [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Materials Science Department, University of Patras, 26504 Patras (Greece); Goschew, A.; Straub, A.; Fumagalli, P. [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Kapaklis, V.; Wolff, M. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Delimitis, A. [Chemical Process and Energy Resources Institute (CPERI), Centre for Research and Technology Hellas (CERTH), 57001 Thermi, Thessaloniki (Greece); Wilhelm, F.; Rogalev, A. [European Synchrotron Radiation Facility (ESRF), B.P.220, 38043 Grenoble (France); Pappas, S. D. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden)

    2014-03-17

    Ni/EuS multilayers with excellent multilayer sequencing are deposited via e-beam evaporation on the native oxide of Si(100) wafers at 4 × 10{sup −9} millibars. The samples have very small surface and interface roughness and show sharp interfaces. Ni layers are nanocrystalline 4–8 nm thick and EuS layers are 2–4 nm thick and are either amorphous or nanocrystalline. Unlike for Co/EuS multilayers, all Eu ions are in divalent (ferromagnetic) state. We show a direct antiferromagnetic coupling between EuS and Ni layers. At room temperature, the EuS layers are spin-polarized due to the proximity of Ni. Therefore, Ni/EuS is a candidate for room-temperature spintronics applications.

  8. Corrosion surface protection by using titanium carbon nitride/titanium-niobium carbon nitride multilayered system

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.C., E-mail: jcesarca@calima.univalle.edu.co [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Amaya, C. [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Laboratorio de Recubrimientos Duros, CDT-ASTIN SENA, Cali (Colombia); Cabrera, G. [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Esteve, J. [Department de Fisica Aplicada i Optica, Universitat de Barcelona, Catalunya (Spain); Aperador, W. [Universidad Militar Nueva Granada Bogota D.C (Colombia); Gomez, M.E. [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Prieto, P. [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Centro de Excelencia en Nuevos Materiales, CENM, Calle 13 100-00 Edificio 320, espacio 1026, Cali (Colombia)

    2011-07-29

    The aim of this work is the improvement of the electrochemical behavior of 4140 steel substrate using TiCN/TiNbCN multilayered system as a protective coating. We have grown [TiCN/TiNbCN]{sub n} multilayered via reactive r.f. magnetron sputtering technique in which was varied systematically the bilayer period ({Lambda}), and the bilayer number (n), maintaining constant the total thickness of the coatings ({approx} 3 {mu}m). The coatings were characterized by X-ray diffraction (XRD), optical microscopy, electron microscopy and transmission electron microscopy assisted with selected area electron diffraction. The electrochemical properties were studied by Electrochemical Impedance Spectroscopy and Tafel curves. XRD results showed a preferential growth in the face-centered cubic (111) crystal structure for [TiCN/TiNbCN]{sub n} multilayered coatings [1]. In this work was obtained the maximum corrosion resistance for the coating with ({Lambda}) equal to 15 nm, corresponding to n = 200 bilayered. The polarization resistance and corrosion rate were around 8.6 kOhm cm{sup 2} and 7.59 . 10{sup -4} mm/year, these values were 8.6 and 0.001 times better than those showed by the uncoated 4140 steel substrate (1.0 kOhm and 0.57 mm/year), respectively. The improvement of the electrochemical behavior of the 4140 coated with this TiCN/TiNbCN multilayered system can be attributed to the presence of several interfaces that act as obstacles for the inward and outward diffusions of Cl{sup -} ion species, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface. Moreover, the interface systems affect the means free path on the ions toward the metallic substrate, due to the decreasing of the defects presented in the multilayered coatings.

  9. Corrosion surface protection by using titanium carbon nitride/titanium-niobium carbon nitride multilayered system

    International Nuclear Information System (INIS)

    Caicedo, J.C.; Amaya, C.; Cabrera, G.; Esteve, J.; Aperador, W.; Gomez, M.E.; Prieto, P.

    2011-01-01

    The aim of this work is the improvement of the electrochemical behavior of 4140 steel substrate using TiCN/TiNbCN multilayered system as a protective coating. We have grown [TiCN/TiNbCN] n multilayered via reactive r.f. magnetron sputtering technique in which was varied systematically the bilayer period (Λ), and the bilayer number (n), maintaining constant the total thickness of the coatings (∼ 3 μm). The coatings were characterized by X-ray diffraction (XRD), optical microscopy, electron microscopy and transmission electron microscopy assisted with selected area electron diffraction. The electrochemical properties were studied by Electrochemical Impedance Spectroscopy and Tafel curves. XRD results showed a preferential growth in the face-centered cubic (111) crystal structure for [TiCN/TiNbCN] n multilayered coatings [1]. In this work was obtained the maximum corrosion resistance for the coating with (Λ) equal to 15 nm, corresponding to n = 200 bilayered. The polarization resistance and corrosion rate were around 8.6 kOhm cm 2 and 7.59 . 10 -4 mm/year, these values were 8.6 and 0.001 times better than those showed by the uncoated 4140 steel substrate (1.0 kOhm and 0.57 mm/year), respectively. The improvement of the electrochemical behavior of the 4140 coated with this TiCN/TiNbCN multilayered system can be attributed to the presence of several interfaces that act as obstacles for the inward and outward diffusions of Cl - ion species, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface. Moreover, the interface systems affect the means free path on the ions toward the metallic substrate, due to the decreasing of the defects presented in the multilayered coatings.

  10. Interface Anywhere

    Data.gov (United States)

    National Aeronautics and Space Administration — Current paradigms for crew interfaces to the systems that require control are constrained by decades old technologies which require the crew to be physically near an...

  11. Figure correction of multilayer coated optics

    Science.gov (United States)

    Chapman; Henry N. , Taylor; John S.

    2010-02-16

    A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1-n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

  12. Multilayer Nanoporous Graphene Membranes for Water Desalination.

    Science.gov (United States)

    Cohen-Tanugi, David; Lin, Li-Chiang; Grossman, Jeffrey C

    2016-02-10

    While single-layer nanoporous graphene (NPG) has shown promise as a reverse osmosis (RO) desalination membrane, multilayer graphene membranes can be synthesized more economically than the single-layer material. In this work, we build upon the knowledge gained to date toward single-layer graphene to explore how multilayer NPG might serve as a RO membrane in water desalination using classical molecular dynamic simulations. We show that, while multilayer NPG exhibits similarly promising desalination properties to single-layer membranes, their separation performance can be designed by manipulating various configurational variables in the multilayer case. This work establishes an atomic-level understanding of the effects of additional NPG layers, layer separation, and pore alignment on desalination performance, providing useful guidelines for the design of multilayer NPG membranes.

  13. Interferential multi-layer mirrors for X-UV radiation: fabrication, characterization and applications

    International Nuclear Information System (INIS)

    Youn Ki Byoung

    1987-01-01

    This research thesis reports the fabrication of W/C, Ni/C and Mo/C interferential multi-layer mirrors which can be used in the X-UV domain. They have been manufactured by cathodic pulverisation by using a new system for the in-situ control of the thickness of deposited layers, based on the measurement, sampling and real time integration of the ionic current which goes through the target during the coating process. Different methods (X ray diffraction at different wavelengths, electron microscopy and diffraction, in situ electronic resistivity measurement) have been used to study the main parameters which govern the multi-layer reflectivity: structure, substrate and interface roughness, minimum thickness to be deposited to obtain a continuous layer, number of bi-layers, stacking evenness, rate of absorbent element thickness to the period. Absolute reflectivity measurements have been performed by using short wavelength synchrotron radiation and the S component of polarised soft X rays obtained after double reflection on two parallel multi-layer mirrors oriented according to the Brewster angle. Ferromagnetic properties of Ni/C multi-layers have been studied to investigate fundamental magnetic properties, and to obtain additional information on interface structure [fr

  14. Temperature and cooling field dependent exchange coupling in [Cr/Gd]{sub 5} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Z.W.; Chen, H.J.; Jiang, W.D.; Wang, J.F.; Yu, S.J. [Department of Physics, China Jiliang University, Hangzhou (China); Hou, Y.L.; Lu, B.; Ye, Q.L. [Department of Physics, Hangzhou Normal University, Hangzhou (China)

    2016-09-15

    Exchange coupling has been investigated in the [Cr/Gd]{sub 5} multilayers deposited at 25, 200, and 400 C, where the Neel temperature (T{sub N}) of antiferromagnetic Cr is slightly higher than the Curie temperature (T{sub C}) of ferromagnetic Gd. It was found that the exchange coupling existed not only at T{sub C} < T < T{sub N}, but also above the temperature (T{sub N}) of antiferromagnetic orderings with incommensurate spin-density wave structures transiting to paramagnetic state. These results can be discussed in terms of the crucial role played by the antiferromagnetic spins of Cr with commensurate spin-density wave structures in the vicinity of the Cr/Gd interfaces. Moreover, the exchange coupling of the multilayers grown at different temperatures exhibited different dependencies on the measuring temperature and the cooling field, respectively. Positive exchange bias was observed in the multilayers grown at 200 and 400 C. The interfacial roughness, grain size, and the antiferromagnetic orderings of Cr may be responsible for the anomalous exchange coupling of the multilayers. In addition, the competition between the exchange coupling at Cr/Gd interfaces and the external field-Cr surface magnetic coupling can explain the appearance of negative or positive exchange bias. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Minimized thermal conductivity in highly stable thermal barrier W/ZrO{sub 2} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Doering, Florian; Major, Anna; Eberl, Christian; Krebs, Hans-Ulrich [University of Goettingen, Institut fuer Materialphysik, Goettingen (Germany)

    2016-10-15

    Nanoscale thin-film multilayer materials are of great research interest since their large number of interfaces can strongly hinder phonon propagation and lead to a minimized thermal conductivity. When such materials provide a sufficiently small thermal conductivity and feature in addition also a high thermal stability, they would be possible candidates for high-temperature applications such as thermal barrier coatings. For this article, we have used pulsed laser deposition in order to fabricate thin multilayers out of the thermal barrier material ZrO{sub 2} in combination with W, which has both a high melting point and high density. Layer thicknesses were designed such that bulk thermal conductivity is governed by the low value of ZrO{sub 2}, while ultrathin W blocking layers provide a high number of interfaces. By this phonon scattering, reflection and shortening of mean free path lead to a significant reduction in overall thermal conductivity even below the already low value of ZrO{sub 2}. In addition to this, X-ray reflectivity measurements were taken showing strong Bragg peaks even after annealing such multilayers at 1300 K. Those results identify W/ZrO{sub 2} multilayers as desired thermally stable, low-conductivity materials. (orig.)

  16. Dynamical diffraction in periodic multilayers

    CERN Document Server

    Sears, V F

    1997-01-01

    Exact reflectivity curves are calculated numerically for various periodic multilayers using the optical matrix method in order to test the dynamical theory of diffraction. The theory is generally valid for values of the bilayer thickness d up to about 100 A. For somewhat larger values of d, where the theory begins to break down, the initial discrepancy is in the phase of the oscillations in the wings of the peaks. For very large values of d, where the first-order Bragg peak approaches the edge of the mirror reflection, two general types of multilayers can be distinguished. In the first (typified in the present work by Ni/Ti), there is a large (30% or more) reduction in the actual value of the critical wave vector for total reflection while, in the second (typified here by Fe/Ge), there is very little reduction (3 % or so). The origin of these two very different types of behavior is explained. It is also shown that, within the dynamical theory of diffraction, the change in the position of the center of the Dar...

  17. Shape-induced anisotropy in antiferromagnetic nanoparticles

    International Nuclear Information System (INIS)

    Gomonay, O.; Kondovych, S.; Loktev, V.

    2014-01-01

    High fraction of the surface atoms considerably enhances the influence of size and shape on the magnetic and electronic properties of nanoparticles. Shape effects in ferromagnetic nanoparticles are well understood and allow us to set and control the parameters of a sample that affect its magnetic anisotropy during production. In the present paper we study the shape effects in the other widely used magnetic materials – antiferromagnets, – which possess vanishingly small or zero macroscopic magnetization. We take into account the difference between the surface and bulk magnetic anisotropy of a nanoparticle and show that the effective magnetic anisotropy depends on the particle shape and crystallographic orientation of its faces. The corresponding shape-induced contribution to the magnetic anisotropy energy is proportional to the particle volume, depends on magnetostriction, and can cause formation of equilibrium domain structure. Crystallographic orientation of the nanoparticle surface determines the type of domain structure. The proposed model allows us to predict the magnetic properties of antiferromagnetic nanoparticles depending on their shape and treatment. - Highlights: • We demonstrate that the shape effects in antiferromagnetic nanoparticles stem from the difference of surface and bulk magnetic properties combined with strong magnetoelastic coupling. • We predict shape-induced anisotropy in antiferromagnetic particles with large aspect ratio. • We predict different types of domain structures depending on the orientation of the particle faces

  18. Simultaneous analysis of Grazing Incidence X-Ray reflectivity and X-ray standing waves from periodic multilayer systems

    NARCIS (Netherlands)

    Yakunin, S.N.; Makhotkin, Igor Alexandrovich; Chuyev, M.A.; Seregin, A.Y.; Pashayev, E.M.; Louis, Eric; van de Kruijs, Robbert Wilhelmus Elisabeth; Bijkerk, Frederik; Kovalchuk, M.V.

    2012-01-01

    Structural analysis of periodic multilayers with small period thickness (~4 nm) is a challenging task, especially when thicknesses of intermixed interfaces become comparable to individual layer thicknesses. In general, angular dependent X-ray fluorescence measurements, excited by the X-ray standing

  19. Lattice Boltzmann method for short-pulsed laser transport in a multi-layered medium

    International Nuclear Information System (INIS)

    Zhang, Yong; Yi, Hong-Liang; Tan, He-Ping

    2015-01-01

    We construct a lattice Boltzmann method (LBM) for transient radiative transfer in one-dimensional multi-layered medium with distinct refractive index in each layer. The left boundary is irradiated normally by a short-pulsed laser. The Fresnel interfaces conditions, which incorporate reflection and refraction, are used at the boundaries and the interfaces. Based on the Fresnel's law and Snell's law, the interfacial intensity formulas are introduced. The collimated and diffuse intensities are treated individually. At a transient time step, the collimated component is first solved by LBM and then embedded into the transient radiative transfer equation as a source term. To keep the consistency of the directions in all the layers, angular interpolation of the intensities at the interfaces is adopted. The transient radiative transfer in a two-layer medium is first investigated, and the time-resolved results are validated by comparing with those by the Monte Carlo method (MCM). Of particular interest, the angular intensities along the slab at different times are presented to illustrate a variety of interesting phenomena, and the discontinuous nature of the intensity at the interfaces is discussed. The effects of various parameters on the time-resolved signals are examined. - Highlights: • Transient radiative transfer in a multi-layered medium is solved by LBM. • The boundary and interfaces are all considered as Fresnel surfaces. • The LBM solution for the collimated pulse is derived. • Discontinuous nature of the intensity at the interface is illustrated and discussed

  20. Large Friction Anisotropy of a Polydiacetylene Monolayer

    International Nuclear Information System (INIS)

    Burns, A.R.; Carpick, R.W.; Sasaki, D.Y.

    1999-01-01

    Friction force microscopy measurements of a polydiacetylene monolayer film reveal a 300% friction anisotropy that is correlated with the film structure. The film consists of a monolayer of the red form of N-(2-ethanol)- 10,12 pentacosadiynamide, prepared on a Langmuir trough and deposited on a mica substrate. As confirmed by atomic force microscopy and fluorescence microscopy, the monolayer consists of domains of linearly oriented conjugated backbones with pendant hydrocarbon side chains above and below the backbones. Maximum friction occurs when the sliding direction is perpendicular to the backbone. We propose that the backbones impose anisotropic packing of the hydrocarbon side chains which leads to the observed friction anisotropy. Friction anisotropy is therefore a sensitive, optically-independent indicator of polymer backbone direction and monolayer structural properties

  1. Measurements of magnetic anisotropy in sickle cells

    International Nuclear Information System (INIS)

    Salvo Souza, L.H. de.

    1982-03-01

    Room temperature magnetic measurements in deoxigenated sickle cells showed the existence of magnetic anisotropy, Δchi=1,29 x 10 -3 . This effect was supposed paramagnetic and considered to be due to the iron atoms of the hemoglobin molecules which are one over the other, forming ordered chains inside the erythrocytes. Low temperature (liquid He - 4,2K) measurements of the magnetic anisotropy of sickle cells and normal red blood cells diluted in a cryoprotector was made to confirm the paramagnetic origin of the fenomena. For that purpose it was used a superconductor magnetometer coupled to a SQUID, developed in the 'Laboratorio do Estado Solido do Departamento de Fisica da PUC-RJ'. The results obtained seem to confirm the expected paramagnetic anisotropy and, furthermore, suggest the presence of magnetic interactions among the iron atoms in the sickle cells samples. (Author) [pt

  2. COSMIC-RAY TRANSPORT AND ANISOTROPIES

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, Peter L. [MPI for Radioastronomy, Auf dem Huegel 69, D-53121 Bonn (Germany); Becker Tjus, Julia; Mandelartz, Matthias [Ruhr-Universitaet Bochum, Fakultaet fuer Physik and Astronomie, Theoretische Physik I, D-44780 Bochum (Germany); Seo, Eun-Suk [Department of Physics, University of Maryland, College Park, MD 20742 (United States)

    2013-05-10

    We show that the large-scale cosmic-ray anisotropy at {approx}10 TeV can be explained by a modified Compton-Getting effect in the magnetized flow field of old supernova remnants. Cosmic rays arrive isotropically to the flow field and are then carried along with the flow to produce a large-scale anisotropy in the arrival direction. This approach suggests an optimum energy scale for detecting the anisotropy. Two key assumptions are that propagation is based on turbulence following a Kolmogorov law and that cosmic-ray interactions are dominated by transport via cosmic-ray-excited magnetic irregularities through the stellar wind of an exploding star and its shock shell. A prediction is that the amplitude is smaller at lower energies due to incomplete sampling of the velocity field and also smaller at larger energies due to smearing.

  3. Thickness and bilayer number dependence on exchange bias in ferromagnetic/antiferromagnetic multilayers based on La{sub 1−x}Ca{sub x}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Departamento de Física y Química, Universidad Nacional de Colombia-Sede Manizales, A.A. 127 Manizales (Colombia); Agudelo-Giraldo, J.D. [Departamento de Física y Química, Universidad Nacional de Colombia-Sede Manizales, A.A. 127 Manizales (Colombia); Grupo de Investigación y Desarrollo en Informática y Telecomunicaciones, Universidad de Manizales, Manizales (Colombia); Restrepo, J. [Grupo de Magnetismo y Simulación, Instituto de Física, Universidad de Antioquia, A.A. 1226 Medellín (Colombia)

    2014-05-01

    In this work, simulations of ferromagnetic/antiferromagnetic multilayers of La{sub 1−x}Ca{sub x}MnO{sub 3} have been carried out by using the Monte Carlo method combined with the Metropolis algorithm and the classical Heisenberg model. In the Hamiltonian we have considered three contributions: nearest neighbor exchange interaction, magnetocrystalline anisotropy and Zeeman interaction. Samples were built by including three types of Mn ions depending on their valence state and type of ionic orbital. Both the number of layers and the antiferromagnetic layer thickness influence on the exchange bias phenomenon are analyzed. Hysteresis loops results exhibit not only a shift as evidence of exchange bias but also the formation of plateaus or steps caused by the presence of more than one interface and the low layers thickness. Each layer presents a strong magnetic behavior because the magneto static energy favors formation of multi-domains in contrast with the single-domains of a single layer FM producing one sub-Loop of each domain (each layer). On the other hand, as the number of layers (n) increases, the sub-cycles tend to disappear. As the plateaus disappear, the system is more effective, increasing the coercive and bias fields. Moreover, domain sizes (layers thickness) also affect the shape of the hysteresis loop. On increasing the thickness of the AFM layer, a decrease in the plateaus produced by the uncoupling is generated.

  4. Photoluminescence properties of perovskite multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Macario, Leilane Roberta; Longo, Elson, E-mail: leilanemacario@gmail.com [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil); Mazzo, Tatiana Martelli [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil); Bouquet, Valerie; Deputier, Stephanie; Ollivier, Sophie; Guilloux-Viry, Maryline [Universite de Rennes (France)

    2016-07-01

    Full text: The knowledge of the optical properties of thin films is important in many scientific, technological and industrial applications of thin films such as photoconductivity, solar energy, photography, and numerous other applications [1]. In this study, perovskite type oxides were grown by pulsed laser deposition [2] in order to obtain thin films with applicable optical properties. The LaNiO{sub 3} (LN), BaTiO{sub 3} (BT) and KNbO{sub 3} (KNb) targets were prepared by solid-state reaction. The X-ray Diffraction revealed the presence of the desired phases, containing the elements of interest in the targets and in the thin films that were produced. The LN, BT and KNb thin films were polycrystalline and the corresponding diffraction peaks were indexed in the with JCPDS cards n. 00-033-0711, n. 00-005-0626, and n. 00-009-0156, respectively. The multilayers films were polycrystalline. The majority of the micrographs obtained by scanning electron microscopy presented films with a thickness from 100 to 400 nm. The photoluminescent (PL) emission spectra of thin films show different broad bands that occupies large region of the visible spectrum, ranging from about 300-350 to 600-650 nm of the electromagnetic spectrum. The PL emission is associated with the order-disorder structural, even small structural changes can modify the interactions between electronic states. The structural disorder results in formation of new energy levels in the forbidden region. The proximity or distance of these new energy levels formed in relation to valence band and to the conduction band results in PL spectra located at higher or lower energies. These interactions change the electronic states which can be influenced by defects, particularly the interface defects between the layers of the thin films. The presence of defects results in changes in the broad band matrix intensity and in displacement of the PL emission maximum. (author)

  5. Anisotropy of dilepton emission from nuclear collisions

    International Nuclear Information System (INIS)

    Bratkovskaya, E.L.; Teryaev, O.V.; Toneev, V.D.; Joint Inst. for Nuclear Research, Dubna

    1994-01-01

    Attention is paid to studying the angular characteristics of e + e - pairs created in collisions with nuclear targets at intermediate and relativistic energies. Arising due to general spin and angular momentum constraints, the dilepton anisotropy seems to be quite sensitive to the contribution of different sources and may be used for disentangling these sources (or models) as well as an additional signature of a possible chiral symmetry restoration and phase transition of hadrons into the quark-gluon plasma. An anisotropy estimate for some dilepton sources is given and its relevance to the problems mentioned is discussed

  6. Anisotropy of dilepton emission from nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bratkovskaya, E.L.; Teryaev, O.V. [Joint Inst. for Nuclear Research, Dubna (Russian Federation). Bogolubov Lab. of Theoretical Physics; Toneev, V.D. [Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory]|[Joint Inst. for Nuclear Research, Dubna (Russian Federation). Bogolubov Lab. of Theoretical Physics

    1994-11-07

    Attention is paid to studying the angular characteristics of e{sup +}e{sup {minus}} pairs created in collisions with nuclear targets at intermediate and relativistic energies. Arising due to general spin and angular momentum constraints, the dilepton anisotropy seems to be quite sensitive to the contribution of different sources and may be used for disentangling these sources (or models) as well as an additional signature of a possible chiral symmetry restoration and phase transition of hadrons into the quark-gluon plasma. An anisotropy estimate for some dilepton sources is given and its relevance to the problems mentioned is discussed.

  7. Anisotropy of the Topopah Spring Member Tuff

    International Nuclear Information System (INIS)

    Martin, R.J. III; Boyd, P.J.; Haupt, R.W.; Price, R.H.

    1992-07-01

    Mechanical properties of the tuffaceous rocks within Yucca Mountain are needed for near and far-field modeling of the potential nuclear waste repository. If the mechanical properties are significantly anisotropic (i.e., direction-dependent), a more complex model is required. Relevant data from tuffs tested in earlier studies indicate that elastic and strength properties are anisotropic. This scoping study confirms the elastic anisotropy and concludes some tuffs are transversely isotropic. An approach for sampling and testing the rock to determine the magnitude of the anisotropy is proposed

  8. Magnetocrystalline and configurational anisotropies in Fe nanostructures

    International Nuclear Information System (INIS)

    Vavassori, P.; Bisero, D.; Carace, F.; Liberati, M.; Di Bona, A.; Gazzadi, G.C.; Valeri, S.

    2005-01-01

    Arrays of single-crystal Fe micron and submicron squares and disks, have been fabricated using a focused ion beam apparatus from a film epitaxially grown on MgO. The hysteresis loops of the patterned areas differ from those of the continuous film as a consequence of the different reversal determined by the lateral confinement of the Fe film. By means of modulated field magneto-optical anisometry measurements we studied the symmetry and the strength of the overall anisotropy. For the smaller square elements we observed a higher-order term in the overall anisotropy with eightfold symmetry arising from the configurational contribution

  9. Development of a combined rotation anisotropy SHG, laser scanning and interferometric SHG microscopy system for material investigations

    International Nuclear Information System (INIS)

    Prylepa, A.

    2015-01-01

    This thesis presents the enhancement of advanced methods of nonlinear optics and their experimental implementation, in particular for optical second harmonic generation (SHG), and the results of further non-destructive investigations of the surfaces and interface structures of various materials by means of these methods. According to the phenomenological theory, SHG process is forbidden in a bulk of centrosymmetric media in dipole approximation. Thereby, main sources of SHG response are localised in the regions of material where centrosymmetry is broken, in the first place these are surfaces and interfaces. Therefore, the SHG process is highly sensitive to the properties of the surfaces and interfaces of centrosymmetric media that makes SHG an attractive tool for the investigation of materials. In our work, we focused on the experimental implementation and improvement of the following techniques of SHG analysis: rotation anisotropy SHG (RA-SHG), laser scanning SHG microscopy (LS-SHGM), and interferometric SHG microscopy (iSHGM). These techniques have unique capabilities, e.g., molecular contrast and polarisation sensitivity, for the non-invasive investigation of materials. Additionally, an optical coherence microscopy (OCM) technique was implemented for the simultaneous coherent detection of the linear optical response. All the mentioned experimental techniques were embedded, without a deterioration of the main possibilities, in one combined experimental setup providing simultaneous detection of linear and nonlinear optical responses. It should be noted that as a main light source we used a broadband (62 nm) femtosecond fiber laser working at central wavelength of 1560 nm, since such a light source allows to obtain a deeper penetration as compared to the light sources in the visible range penetration depth of more than 200 µm was easily achieved). We would like to underline that such a combined low-coherence iSHGM and OCM setup at the central fundamental

  10. Tuning magnetic properties of non-collinear magnetization configuration in Pt/[Pt/Co]{sub 6}/Pt/Co/Pt multilayer structure

    Energy Technology Data Exchange (ETDEWEB)

    Kalaycı, Taner, E-mail: taner.kalayci@marmara.edu.tr [Department of Physics, Marmara University, 34722, Kadıköy, Istanbul (Turkey); Deger, Caner [Department of Physics, Marmara University, 34722, Kadıköy, Istanbul (Turkey); Akbulut, Salih [Department of Physics, Gebze Technical University, 41400, Gebze, Kocaeli (Turkey); Yildiz, Fikret, E-mail: fyildiz@gtu.edu.tr [Department of Physics, Gebze Technical University, 41400, Gebze, Kocaeli (Turkey)

    2017-08-15

    Highlights: • Effects of Pt spacer and reference layers thickness are investigated by MOKE and FMR. • Controlling of non-collinear states in multilayered thin film systems is studied. • Micromagnetic approach is used for modeling of magnetic multilayered structure. • Magnetic parameters are determined by a simulation based on metropolis algorithm. - Abstract: In this study, effects of Pt spacer and Co reference layers thickness in [Co/Pt]{sub 6}/Pt/Co multilayer have been revealed to tailor magnetization directions in non-collinear configuration. Magneto-optic Kerr effect and ferromagnetic resonance techniques were employed to investigate magnetic properties. Bilinear coupling between [Co/Pt]{sub 6} and Co layers and anisotropy constants were determined by a micromagnetic simulation based on metropolis algorithm. 3 nm spacer causes ferromagnetic coupling while the samples have 4 and 5 nm spacer are coupled anti-ferromagneticaly. Also, tuning magnetic anisotropy of [Co/Pt]{sub 6} layer was accomplished by Co reference layer. It is revealed that controlling of non-collinear states in such systems is possible by variation of thickness of spacer and reference layers and [Co/Pt]{sub 6}/t{sub Pt}/t{sub Co} trilayer system can be used in multilayered magnetic systems.

  11. Multilayer Insulation Ascent Venting Model

    Science.gov (United States)

    Tramel, R. W.; Sutherlin, S. G.; Johnson, W. L.

    2017-01-01

    The thermal and venting transient experienced by tank-applied multilayer insulation (MLI) in the Earth-to-orbit environment is very dynamic and not well characterized. This new predictive code is a first principles-based engineering model which tracks the time history of the mass and temperature (internal energy) of the gas in each MLI layer. A continuum-based model is used for early portions of the trajectory while a kinetic theory-based model is used for the later portions of the trajectory, and the models are blended based on a reference mean free path. This new capability should improve understanding of the Earth-to-orbit transient and enable better insulation system designs for in-space cryogenic propellant systems.

  12. Thermal transfer in multilayer materials

    Energy Technology Data Exchange (ETDEWEB)

    Bouayad, H.; Mokhtari, A.; Martin, C.; Fauchais, P. [Laboratoire de Materiaux Ceramiques et Traitements de Surface, 87 - Limoges (France)

    1993-12-31

    It is easier to measure the thermal diffusivity (a) of material rather than its thermal conductivity (k), a simple relationship (k=a cp) allowing to calculate k provided and cp are measured. However this relationship applies only if the considered material is homogenous. For composite materials, especially for multilayers ones, we have developed an analytical model and a numerical one. The first one allows to determine the thermal diffusivity and conductivity of a two-layer material. The second one allows to determine the thermal diffusivity of one of the layers provided the values of (a) are known for the two other layers (for a two or three-layer material). The use of the two models to calculate the apparent diffusivity of a two layer material results in values in fairly good agreement. (Authors). 4 refs., 3 figs., 3 tabs.

  13. Controlling the competing magnetic anisotropy energies in FineMET amorphous thin films with ultra-soft magnetic properties

    Directory of Open Access Journals (Sweden)

    Ansar Masood

    2017-05-01

    Full Text Available Thickness dependent competing magnetic anisotropy energies were investigated to explore the global magnetic behaviours of FineMET amorphous thin films. A dominant perpendicular magnetization component in the as-deposited state of thinner films was observed due to high magnetoelastic anisotropy energy which arises from stresses induced at the substrate-film interface. This perpendicular magnetization component decreases with increasing film thickness. Thermal annealing at elevated temperature revealed a significant influence on the magnetization state of the FineMET thin films and controlled annealing steps leads to ultra-soft magnetic properties, making these thin films alloys ideal for a wide range of applications.

  14. High yield Cu-Co CPP GMR multilayer sensors

    International Nuclear Information System (INIS)

    Spallas, J., Mao, M., Law, B., Grabner, F., Cerjan, C., O'Kane, O.

    1997-01-01

    We have fabricated and tested GMR magnetic flux sensors that operate in the CPP mode. This work is a continuation of the ultra-high density magnetic sensor research introduced at INTERMAG 96. We have made two significant modifications to the process sequence. First, contact to the sensor is made through a metal conduit deposited in situ with the multilayers. This deposition replaces electroplating. This configuration ensures a good electrical interface between the top of multilayer stack and the top contact, and a continuous, conductive current path to the sensor. The consequences of this modification are an increase in yield of operational devices to ≥90% per wafer and a significant reduction of the device resistance to ≤560 milliohms and of the uniformity of the device resistance to ≤3%. Second, the as-deposited multilayer structure has been changed from [Cu 30 angstrom/Co 20 angstrom] 18 (third peak) to [Cu 20.5 angstrom/Co 12 angstrom] 30 (second peak) to increase the CPP and CIP responses. The sheet film second peak CIP GMR response is 18% and the sensitivity is 0.08 %/Oe. The sheet film third peak CIP GMR response is 8% and the sensitivity is 0. 05 %/Oe. The second peak CPP GMR response averaged over twenty devices on a four inch silicon substrate is 28% ± 6%. The response decreases radially from the substrate center. The average response at the center of the substrate is 33% ± 4%. The average second peak CPP sensitivity is 0.09 %/Oe ± 0.02 %/Oe. The best second peak CPP response from a single device is 39%. The sensitivity of that device is 0.13 %/Oe. The third peak CPP GMR response is approximately 14 %. The third peak CPP response sensitivity is 0.07 %/Oe. 6 refs., 3 figs

  15. Superconductivity in multilayer perovskite. Weak coupling analysis

    International Nuclear Information System (INIS)

    Koikegami, Shigeru; Yanagisawa, Takashi

    2006-01-01

    We investigate the superconductivity of a three-dimensional d-p model with a multilayer perovskite structure on the basis of the second-order perturbation theory within the weak coupling framework. Our model has been designed with multilayer high-T c superconducting cuprates in mind. In our model, multiple Fermi surfaces appear, and the component of a superconducting gap function develops on each band. We have found that the multilayer structure can stabilize the superconductivity in a wide doping range. (author)

  16. Nondestructive diagnosis of multilayer electronic plates

    International Nuclear Information System (INIS)

    Matvienko, A.N.; Savin, D.O.; Yas'ko, A.V.

    1992-01-01

    Methods of non-destructive tomographic investigation into multilayer printed plates using x radiation are described. Mathematic problem setting is given, experimental facility and methods for source data ecquisition are described. A special attention is paid to the consideration of the main factors differing the actual problem setting from the idealized one. Methods for accounting and correction of these factors are described. The efficiency of the approach proposed is demonstrated using the actual problems of reducing separate layers of multilayer printed plate metallization. The method developed is useful when exersizing control over multilayer printed plate production

  17. Designing Interfaces

    CERN Document Server

    Tidwell, Jenifer

    2010-01-01

    Despite all of the UI toolkits available today, it's still not easy to design good application interfaces. This bestselling book is one of the few reliable sources to help you navigate through the maze of design options. By capturing UI best practices and reusable ideas as design patterns, Designing Interfaces provides solutions to common design problems that you can tailor to the situation at hand. This updated edition includes patterns for mobile apps and social media, as well as web applications and desktop software. Each pattern contains full-color examples and practical design advice th

  18. Effect of anisotropic plasticity on mixed mode interface crack growth

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Legarth, Brian Nyvang

    2007-01-01

    different anisotropic yield criteria to account for the plastic anisotropy. Conditions of small-scale yielding are assumed, and due to the mismatch of elastic properties across the interface the corresponding oscillating stress singularity field is applied as boundary conditions on the outer edge...

  19. Magnetotransport and magnetization reversal of electrodeposited multilayer nanowires

    Science.gov (United States)

    Tang, Xueti

    2007-12-01

    Electrodeposited magnetic multilayer nanowires are ideal materials to study nanoscale magnetism and the giant magnetoresistance (GMR) in the current-perpendicular-to-plane (CPP) geometry. This is because the diameter of each nanowire is uniform, the surface of the nanowire is smooth, and the thickness of both the magnetic and non-magnetic layers can be varied to either larger or smaller than the spin diffusion length which is an important parameter in magnetotransport study. In addition, the aspect ratio (layer-thickness/diameter) that is related to shape anisotropy can be varied for magnetization reversal study. There has been little understanding in the magnetization reversal mechanism of multilayer nanowires, which is complicated due to the dipolar interactions between magnetic layers in each nanowire and between nanowires. The objective of this work is to study the magnetization reversal mechanism of multilayer nanowires using a vibrating sample magnetometer (VSM), where various dipolar interactions are taken into account. Although multilayer nanowires are ideal for the study of the CPP-GMR effect, there remains technical difficulty in making an electrical contact with individual nanowires for the CPP-GMR measurements. In this work, a point-contact method using a conductive plunger tip was developed in-house, that enabled us to measure the CPP-GMR of selected multilayer nanowires in an array of vertically aligned nanowires in each sample. To examine the CPP-GMR and compare the results with theoretical models, the CPP-GMR data were systematically obtained from samples with various magnetic and non-magnetic layer thicknesses. It was found from VSM measurement that the magnetization reversal mode in electrodeposited CoNi/Cu multilayer nanowires depends on the shape and thickness of the CoNi layers where the mode in rod-shaped thick CoNi layers is different from that in disk-shaped thin CoNi layers. The reversal mode in coherent rotation or curling was determined

  20. Magnetic ground and remanent states of synthetic metamagnets with perpendicular anisotropy

    International Nuclear Information System (INIS)

    Kiselev, N S; Roessler, U K; Bogdanov, A N; Hellwig, O

    2011-01-01

    In this work, we summarize our theoretical results within a phenomenological micromagnetic approach for magnetic ground state and nonequilibrium states as topological magnetic defects in multilayers with strong perpendicular anisotropy and antiferromagnetic (AF) interlayer exchange coupling (IEC), e.g. [Co/Pt(Pd)]/Ru(Ir, NiO). We give detailed analysis of our model together with the most representative results which elucidate common features of such systems. We discuss phase diagrams of the magnetic ground state, and compare solutions of our model with experimental data. A model to assess the stability of so-called tiger tail patterns is presented. It is found that these modulated topological defect cannot be stabilized by an interplay between magnetostatic and IEC energies only. It is argued that tiger tail patterns arise as nuclei of ferro-stripe structure in AF domain walls and that they are stabilized by domain wall pinning.

  1. Direct Observation of Field and Temperature Induced Domain Replication in Dipolar Coupled Perpendicular Anisotropy Films

    Energy Technology Data Exchange (ETDEWEB)

    Hauet, T.; Gunther, C.M.; Pfau, B.; Eisebitt, S.; Fischer, P.; Rick, R. L.; Thiele, J.-U.; Hellwig, O.; Schabes, M.E.

    2007-07-01

    Dipolar interactions in a soft/Pd/hard [CoNi/Pd]{sub 30}/Pd/[Co/Pd]{sub 20} multilayer system, where a thick Pd layer between two ferromagnetic units prevents direct exchange coupling, are directly revealed by combining magnetometry and state-of-the-art layer resolving soft x-ray imaging techniques with sub-100-nm spatial resolution. The domains forming in the soft layer during external magnetic field reversal are found to match the domains previously trapped in the hard layer. The low Curie temperature of the soft layer allows varying its intrinsic parameters via temperature and thus studying the competition with dipolar fields due to the domains in the hard layer. Micromagnetic simulations elucidate the role of [CoNi/Pd] magnetization, exchange, and anisotropy in the duplication process. Finally, thermally driven domain replication in remanence during temperature cycling is demonstrated.

  2. Micromagnetic finite element study for magnetic properties of nanocomposite exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems

    Energy Technology Data Exchange (ETDEWEB)

    Ryo, Hyok-Su [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Faculty of Physics, Kim Il Sung University, Pyongyang 999093, Democratic People’s Republic of Korea (Korea, Republic of); Hu, Lian-Xi [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Kim, Jin-Guk [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Faculty of Physics, Kim Il Sung University, Pyongyang 999093, Democratic People’s Republic of Korea (Korea, Republic of); Yang, Yu-Lin [School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-03-15

    In this study, magnetic properties of exchange coupled nanocomposite multilayer thin films constructed alternately with magnetic hard Nd{sub 2}Fe{sub 14}B layers and soft α-Fe layers have been studied by micromagnetic finite element method (FEM). According to the results, effects of the thicknesses of layers and the magneto-crystalline anisotropy on the magnetic properties of the Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems have been estimated. On the other hand, the results have been analyzed by means of efficiency of interphase exchange coupling, which can be estimated by volume ratios of exchange coupled areas between magnetically hard Nd{sub 2}Fe{sub 14}B and soft α-Fe phase layers. The results show that the magnetic properties of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems can be enhanced by efficient interphase exchange coupling between magnetically hard Nd{sub 2}Fe{sub 14}B layers and soft α-Fe layers. - Highlights: • Phase layer thicknesses dependence of magnetic properties of Nd{sub 2}Fe{sub 14}B/α-Fe multilayers. • Analyzation of the effectiveness of exchange coupling between the Nd{sub 2}Fe{sub 14}B and α-Fe layers. • Dependence of the magnetic properties on direction of external field of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayers. • Dependence of the magnetic properties on magneto-crystalline anisotropy of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayers.

  3. Moessbauer Study of Electrodeposited Fe/Fe-Oxide Multilayers

    International Nuclear Information System (INIS)

    Kuzmann, E.; Homonnay, Z.; Klencsar, Z.; Vertes, A.; Lakatos-Varsanyi, M.; Miko, A.; Varga, L.K.; Kalman, E.; Nagy, F.

    2005-01-01

    Iron has been deposited electrochemically by short current pulses in Na-saccharin containing FeII-chloride and sulphate solution electrolytes. Combined electrochemical techniques with initial pulse plating of iron nanolayer and its subsequent anodic oxidation under potential control have been used for production of Fe/Fe-oxide multilayers. 57Fe CEM spectra of pulse plated iron revealed the presence of a minor doublet attributed mainly to γ-FeOOH in addition to the dominant sextet of α-iron. In the case of anodically oxidized pulse plated iron and of samples after repeated deposition of anodically oxidized pulse plated iron an additional minor doublet, assigned to ferrous chloride, also appears in the Moessbauer spectra. A significant change in the magnetic anisotropy of α-iron was observed with the anodic oxidation. The thickness of the layers were estimated from the CEM spectrum data by a modified computer program of the Liljequist method. The coercive field and the power loss versus frequency data showed that the pulse plated iron cores are good inductive elements up to several kHz frequencies

  4. Acoustic axes in weak triclinic anisotropy

    Czech Academy of Sciences Publication Activity Database

    Vavryčuk, Václav

    2005-01-01

    Roč. 163, č. 2 (2005), s. 629-638 ISSN 0956-540X R&D Projects: GA AV ČR IAA3012309 Institutional research plan: CEZ:AV0Z30120515 Keywords : elastic-wave theory * perturbation methods * seismic anisotropy Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.826, year: 2005

  5. Empirical evidence for inertial mass anisotropy

    International Nuclear Information System (INIS)

    Heller, M.; Siemieniec, G.

    1985-01-01

    A several attempts at measuring the possible deviations from inertial mass isotropy caused by a non-uniform distribution of matter are reviewed. A simple model of the inertial mass anisotropy and the results of the currently performed measurements concerning this effect are presented. 34 refs. (author)

  6. Anisotropy of Wood in the Microwave Region

    Science.gov (United States)

    Ziherl, Sasa; Bajc, Jurij; Urankar, Bernarda; Cepic, Mojca

    2010-01-01

    Wood is transparent for microwaves and due to its anisotropic structure has anisotropic dielectric properties. A laboratory experiment that allows for the qualitative demonstration and quantitative measurements of linear dichroism and birefringence in the microwave region is presented. As the proposed experiments are based on the anisotropy (of…

  7. What we learn from CMB Anisotropies

    CERN Multimedia

    CERN. Geneva

    2007-01-01

    George Smoot shared the 2006 Nobel Prize with John Mathere for the discovery of the fluctuations of the cosmic microwave background. In this talk (which will not be the same as the Nobel lecture), he will discuss what we have learned about the universe in the recent past from these anisotropies.

  8. Pseudospin anisotropy classification of quantum Hall ferromagnets

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; MacDonald, A. H.

    2000-01-01

    Roč. 63, č. 3 (2000), s. 035305-1 - 035305-9 ISSN 0163-1829 R&D Projects: GA ČR GA202/98/0085 Institutional research plan: CEZ:AV0Z1010914 Keywords : quantum Hall ferromagnets * anisotropy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.065, year: 2000

  9. Cosmology with cosmic microwave background anisotropy

    Indian Academy of Sciences (India)

    Measurements of CMB anisotropy and, more recently, polarization have played a very important role in allowing precise determination of various parameters of the `standard' cosmological model. The expectation of the paradigm of inflation and the generic prediction of the simplest realization of inflationary scenario in the ...

  10. Magnetic anisotropy in rare-earth metals

    DEFF Research Database (Denmark)

    Nielsen, Mourits; Bjerrum Møller, Hans; Lindgård, Per-Anker

    1970-01-01

    The magnetic field dependence of the energy of long- wavelength magnons in Tb-10%Ho has been studied by inelastic neutron scattering. The results agree with the `frozen-lattice' model, provided that the second-order magnetoelastic effect is taken into account. The planar anisotropy is almost...

  11. Azimuthal anisotropy of jet quenching at LHC

    Indian Academy of Sciences (India)

    Abstract. We analyze the azimuthal anisotropy of jet spectra due to energy loss of hard partons in quark–gluon plasma, created initially in nuclear overlap zone in collisions with non-zero impact parameter. The calculations are performed for semi-central Pb–Pb collisions at LHC energy.

  12. Relative sensitivity of formability to anisotropy

    International Nuclear Information System (INIS)

    Logan, R.W.; Maker, B.N.

    1997-01-01

    This work compares the relative importance of material anisotropy in sheet forming as compared to other material and process variables. The comparison is made quantitative by the use of normalized dependencies of depth to failure (forming limit is reached) on various measures of anisotropy, as well as strain and rate sensitivity, friction, and tooling. Comparisons are made for a variety of forming processes examined previously in the literature as well as two examples of complex stampings in this work. 7 The examples rover a range from nearly pure draw to nearly pure stretch situations, and show that for materials following a quadratic yield criterion, anisotropy is among the most sensitive parameters influencing formability. For materials following higher-exponent yield criteria, the dependency is milder but is still of the order of most other process parameters. However, depending on the particular forming operation, it is shown that in some cases anisotropy may be ignored, whereas in others its consideration is crucial to a good quality analysis

  13. Effective anisotropy through traveltime and amplitude matching

    KAUST Repository

    Wang, Hui

    2014-08-05

    Introducing anisotropy to seismic wave propagation reveals more realistic physics of our Earth\\'s subsurface as compared to the isotropic assumption. However wavefield modeling, the engine of seismic inverse problems, in anisotropic media still suffers from computational burdens, in particular with complex anisotropy such as transversely isotropic (TI) and Orthorhombic anisotropy. We develop effective isotropic velocity and density models to package the effects of anisotropy such that the wave propagation behavior using these effective models approximate those of the original anisotropic model. We build these effective models through the high frequency asymptotic approximation based on the eikonal and transport equations. We match the geometrical behavior of the wave-fields, given by traveltimes, from the anisotropic and isotropic eikonal equations. This matching yields the effective isotropic velocity that approximates the kinematics of the anisotropic wavefield. Equivalently, we calculate the effective densities by equating the anisotropic and isotropic transport equations. The effective velocities and densities are then fed into the isotropic acoustic variable density wave equation to obtain cheaper anisotropic wavefields. We justify our approach by testing it on an elliptical anisotropic model. The numerical results demonstrate a good matching of both traveltime and amplitude between anisotropic and effective isotropic wavefields.

  14. Reactive diffusion and superconductivity of Nb3Al multilayer films

    International Nuclear Information System (INIS)

    Vandenberg, J.M.; Hong, M.; Hamm, R.A.; Gurvitch, M.

    1985-01-01

    Thin films of A15 Nb 3 Al have been prepared by reactive diffusion of sputter-deposited Nb/Al multilayers. The diffusion reactions were studied by in situ annealing x-ray diffraction in the temperature range 50--950 0 C. Initially the Nb and Al sublayers react to form the phase NbAl 3 . This interface reaction prevents the formation of the sigma-phase Nb 2 Al, frequently found as a second phase in A15 Nb 3 Al materials; NbAl 3 reacts with the remaining Nb to form the A15 phase. The highest T/sub c/, 16.2 K measured resistively and 15.2 K inductively, was found in a Nb/Al multilayer with an A15 cell parameter a 0 = 5.195 A which corresponds to approx.20 at. % Al. From a comparison with previous investigations of the T/sub c/ dependence on Al concentration and A15 cell parameter, it is concluded that a small amount of the A15 phase has a higher composition of 22--23 at. % Al

  15. Electrostatics and charge regulation in polyelectrolyte multilayered assembly.

    Science.gov (United States)

    Cherstvy, Andrey G

    2014-05-01

    We examine the implications of electrostatic interactions on formation of polyelectrolyte multilayers, in application to field-effect based biosensors for label-free detection of charged macromolecules. We present a quantitative model to describe the experimental potentiometric observations and discuss its possibilities and limitations for detection of polyelectrolyte adsorption. We examine the influence of the ionic strength and pH on the sensor response upon polyelectrolyte layer-by-layer formation. The magnitude of potential oscillations on the sensor-electrolyte interface predicted upon repetitive adsorption charge-alternating polymers agrees satisfactorily with experimental results. The model accounts for different screening by mobile ions in electrolyte and inside tightly interdigitated multilayered structure. In particular, we show that sensors' potential oscillations are larger and more persistent at lower salt conditions, while they decay faster with the number of layers at higher salt conditions, in agreement with experiments. The effects of polyelectrolyte layer thickness, substrate potential, and charge regulation on the sensor surface triggered by layer-by-layer deposition are also analyzed.

  16. Interface unit

    NARCIS (Netherlands)

    Keyson, D.V.; Freudenthal, A.; De Hoogh, M.P.A.; Dekoven, E.A.M.

    2001-01-01

    The invention relates to an interface unit comprising at least a display unit for communication with a user, which is designed for being coupled with a control unit for at least one or more parameters in a living or working environment, such as the temperature setting in a house, which control unit

  17. Experimental study of flux pinning in NbN films and multilayers: Ultimate limits on critical currents in superconductors

    International Nuclear Information System (INIS)

    Gray, K.E.; Kampwirth, R.T.; Capone, D.W. II; Murduck, J.M.

    1988-08-01

    A flux pinning model is presented which predicts the maximum critical current density attainable in superconductors. That such a limit must exist comes from the realization that flux pinning is strongest in regions of weak superconductivity, but these regions cannot carry a large supercurrent. Since the same regions within the superconductor cannot be used for both pinning and supercurrent conductions, there must be an optimum mix, leading to a maximum J/sub c/. Measurements on films and multilayers of NbN have verified many details of the model including anisotropy effects and a strong reduction in J/sub c/ for defect spacings smaller than the flux core diameter. In an optimized multilayer the pinning force reached /approximately/22% of the theoretical maximum. The implications of these results on the practical applications of NbN films and on the maximum critical current density in the new high temperature superconductors are also discussed. 24 refs., 4 figs

  18. Interface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gariglio, S., E-mail: stefano.gariglio@unige.ch [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland); Gabay, M. [Laboratoire de Physique des Solides, Bat 510, Université Paris-Sud 11, Centre d’Orsay, 91405 Orsay Cedex (France); Mannhart, J. [Max Planck Institute for Solid State Research, 70569 Stuttgart (Germany); Triscone, J.-M. [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland)

    2015-07-15

    Highlights: • We discuss interfacial superconductivity, a field boosted by the discovery of the superconducting interface between LaAlO. • This system allows the electric field control and the on/off switching of the superconducting state. • We compare superconductivity at the interface and in bulk doped SrTiO. • We discuss the role of the interfacially induced Rashba type spin–orbit. • We briefly discuss superconductivity in cuprates, in electrical double layer transistor field effect experiments. • Recent observations of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3} are presented. - Abstract: Low dimensional superconducting systems have been the subject of numerous studies for many years. In this article, we focus our attention on interfacial superconductivity, a field that has been boosted by the discovery of superconductivity at the interface between the two band insulators LaAlO{sub 3} and SrTiO{sub 3}. We explore the properties of this amazing system that allows the electric field control and on/off switching of superconductivity. We discuss the similarities and differences between bulk doped SrTiO{sub 3} and the interface system and the possible role of the interfacially induced Rashba type spin–orbit. We also, more briefly, discuss interface superconductivity in cuprates, in electrical double layer transistor field effect experiments, and the recent observation of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3}.

  19. Formation of hard magnetic L1{sub 0}-FePt/FePd monolayers from elemental multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Nam Hoon

    2007-06-18

    In this thesis, ordered L1{sub 0}-FePt and FePd films of different nominal compositions are prepared from Fe/Pt and Fe/Pd multilayers by annealing. In case of the L1{sub 0}-FePt films the composition of the films is modified by changing the individual elemental layer thicknesses in the multilayer precursors. This simple variation of the composition is the great advantage of the multilayer approach compared to sputtering single alloy layer from an alloy target. The formation mechanism of the fct phase from the multilayers and the microstructural properties are investigated. The characteristics of the hysteresis loop (coercivity {mu}{sub 0}H{sub c}, remanence J{sub r}) and of the intrinsic magnetic properties (anisotropy constant K{sub l}, spontaneous polarization J{sub s}, exchange constant A) of the ordered L1{sub 0}-FePt and FePd films are studied. The effects of the composition of the L1{sub 0}-FePt films on the microstructural and magnetic properties are investigated. The microstructure of these ordered L1{sub 0}-FePt films are then correlated to the magnetic properties with microstructural parameters by investigating the temperature dependence of the coercivity. (orig.)

  20. Thermoelectric characteristics of Pt-silicide/silicon multi-layer structured p-type silicon

    International Nuclear Information System (INIS)

    Choi, Wonchul; Jun, Dongseok; Kim, Soojung; Shin, Mincheol; Jang, Moongyu

    2015-01-01

    Electric and thermoelectric properties of silicide/silicon multi-layer structured devices were investigated with the variation of silicide/silicon heterojunction numbers from 3 to 12 layers. For the fabrication of silicide/silicon multi-layered structure, platinum and silicon layers are repeatedly sputtered on the (100) silicon bulk substrate and rapid thermal annealing is carried out for the silicidation. The manufactured devices show ohmic current–voltage (I–V) characteristics. The Seebeck coefficient of bulk Si is evaluated as 195.8 ± 15.3 μV/K at 300 K, whereas the 12 layered silicide/silicon multi-layer structured device is evaluated as 201.8 ± 9.1 μV/K. As the temperature increases to 400 K, the Seebeck coefficient increases to 237.2 ± 4.7 μV/K and 277.0 ± 1.1 μV/K for bulk and 12 layered devices, respectively. The increase of Seebeck coefficient in multi-layered structure is mainly attributed to the electron filtering effect due to the Schottky barrier at Pt-silicide/silicon interface. At 400 K, the thermal conductivity is reduced by about half of magnitude compared to bulk in multi-layered device which shows the efficient suppression of phonon propagation by using Pt-silicide/silicon hetero-junctions. - Highlights: • Silicide/silicon multi-layer structured is proposed for thermoelectric devices. • Electric and thermoelectric properties with the number of layer are investigated. • An increase of Seebeck coefficient is mainly attributed the Schottky barrier. • Phonon propagation is suppressed with the existence of Schottky barrier. • Thermal conductivity is reduced due to the suppression of phonon propagation

  1. Soft X-ray multilayers and filters

    CERN Document Server

    Wang Zhan Shan; Tang Wei Xing; Qin Shuji; Zhou Bing; Chen Ling Ya

    2002-01-01

    The periodic and non-periodic multilayers were designed by using a random number to change each layer and a suitable merit function. Ion beam sputtering and magnetron sputtering were used to fabricate various multilayers and beam splitters in soft X-ray range. The characterization of multilayers by small angle X-ray diffraction, Auger electron spectroscopy, Rutherford back scattering spectroscopy and reflectivity illustrated the multilayers had good structures and smooth interlayers. The reflectivity and transmission of a beam splitter is about 5%. The fabrication and transmission properties of Ag, Zr were studied. The Rutherford back scattering spectroscopy and auger electron spectroscopy were used to investigate the contents and distributions of impurities and influence on qualities of filters. The attenuation coefficients were corrected by the data obtained by measurements

  2. Lamellar multilayer hexadecylaniline-modified gold nanoparticle ...

    Indian Academy of Sciences (India)

    standard Wilhelmy plate was used for surface pressure sensing. Multilayer ... carried out on a JEOL model 1200EX instrument operated at an accelerating voltage of ... the gold nanoparticles within domains (and reorganization of the domains ...

  3. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad; Farhat, Mohamed; Bagci, Hakan

    2013-01-01

    An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon

  4. Irradiated multilayer film for primal meat packaging

    International Nuclear Information System (INIS)

    Lustig, S.; Schuetz, J.M.; Vicik, S.J.

    1987-01-01

    This patent deals with a heat-shrinkable, multilayer film suitable for use in fabricating bags for packaging primal and sub-primal meat cuts and processed meats. The multilayer film has a first outer layer of a first ethylene-vinyl acetate copolymer, a core layer of a polyvinylidene chloride-vinyl chloride copolymer containing between about 70 weight percent and about 90 weight percent vinylidene chloride as a barrier film, and a second outer layer of a second ethylene-vinyl acetate copolymer. The multilayer film is preferably made by co-extrusion of the layers, and then it is biaxially stretched. After biaxial stretching, the entire multilayer film is substantially uniformly irradiated to a dosage level of between about 2 megarads and about 3 megarads and heat-sealed in the form of a bag. The film is not significantly discoloured by the irradiation and the bag has improved toughness properties and heat-sealing characteristics

  5. Irradiated multilayer film for primal meat packaging

    International Nuclear Information System (INIS)

    Lustig, S.; Schuetz, J.M.; Vicik, S.J.

    1987-01-01

    This patent deals with a heat-shrinkable, multilayer film suitable for use in fabricating bags for packaging primal and sub-primal meat cuts and processed meats. The multilayer film has a first outer layer of an ethylene-vinyl acetate copolymer, a core layer of a barrier film comprising vinylidene chloride-methyl acrylate copolymer, and a second outer layer of an ethylene-vinyl acetate copolymer. The multilayer film is preferably made by co-extrusion of the layers, and then it is biaxially stretched. After biaxial stretching, the multilayer film is irradiated to a dosage level of between 1 megarad and 5 megarads and heat-sealed in the form of a bag. The bag has improved storage stability characteristics

  6. A multilayer innovative solution to improve the adhesion of nanocrystalline diamond coatings

    Energy Technology Data Exchange (ETDEWEB)

    Poulon-Quintin, A., E-mail: poulon@icmcb-bordeaux.cnrs.fr [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Faure, C.; Teulé-Gay, L.; Manaud, J.P. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France)

    2015-03-15

    Highlights: • Improvement of the NCD adhesion on WC-12%Co substrates for tooling applications using a multi-interlayer additional system. • Reduction of the graphite layer thickness and continuity at the interface with the diamond. • Transmission electron microscopy study for a better understanding of the diffusion phenomena occurring at the interfaces. - Abstract: Nano-crystalline diamond (NCD) films grown under negative biased substrates by chemical vapor deposition (CVD) are widely used as surface overlay coating onto cermet WC-Co cutting tools to get better performances. To improve the diamond adhesion to the cermet substrate, suitable multi-layer systems have been added. They are composed of a cobalt diffusion barrier close to the substrate (single and sequenced nitrides layers) coated with a nucleation extra layer to improve the nucleus density of diamond during CVD processing. For all systems, before and after diamond deposition, transmission electron microscopy (TEM) has been performed for a better understanding of the diffusion phenomena occurring at the interfaces and to evaluate the presence of graphitic species at the interface with the diamond. Innovative multilayer system dedicated to the regulation of cobalt diffusion coated with a bilayer system optimized for the carbon diffusion control, is shown as an efficient solution to significantly reduce the graphite layer formation at the interface with the diamond down to 10 nm thick and to increase the adhesion of NCD diamond layer as scratch-tests confirm.

  7. Ordered organic-organic multilayer growth

    Science.gov (United States)

    Forrest, Stephen R; Lunt, Richard R

    2015-01-13

    An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

  8. Size-dependent electronic eigenstates of multilayer organic quantum wells

    International Nuclear Information System (INIS)

    Nguyen Ba An; Hanamura, E.

    1995-09-01

    A detailed theoretical treatment is given eigenfunctions and eigenenergies of a multilayer organic quantum well sandwiched between two different dielectric media. The abrupt change of dielectric constants at the interfaces distorts the wave function and results in possible surface states in addition to propagating states. The proper boundary conditions are accounted for by the method of image charges. Analytic criteria for existence of surface states are established using the nearest layers approximation, which depend not only on the intralayer parameters but also on the number of layers. The size dependence together with the dependence on signs and relative magnitudes of the structure parameters fully determine the energy spectrum of propagating states as well as the number and the location of surface states. (author). 28 refs, 10 figs, 2 tabs

  9. What does anisotropy measure? Insights from increased and decreased anisotropy in selective fiber tracts in schizophrenia.

    Directory of Open Access Journals (Sweden)

    Gabriel A De Erausquin

    2013-03-01

    Full Text Available Schizophrenia is a common, severe and chronically disabling mental illness of unknown cause. Recent MRI studies have focused attention on white matter abnormalities in schizophrenia using diffusion tensor imaging (DTI. Indices commonly derived from DTI include (a mean diffusivity, independent of direction, (b fractional anisotropy (FA or relative anisotropy (RA, (c axial diffusivity, and (d radial diffusivity. In cerebral white matter, contributions to these indices come from fiber arrangements, degree of myelination, and axonal integrity. Relatively pure deficits in myelin result in a modest increase in radial diffusivity, without affecting axial diffusivity and with preservation of anisotropy. Although schizophrenia is not characterized by gross abnormalities of white matter, it does involve a profound dysregulation of myelin-associated gene expression, reductions in oligodendrocyte numbers, and marked abnormalities in the ultrastructure of myelin sheaths. Since each oligodendrocyte myelinates as many as 40 axon segments, changes in the number of oligodendrocytes, and/or in the integrity of myelin sheaths, and/or axoglial contacts can have a profound impact on signal propagation and the integrity of neuronal circuits. Whereas a number of studies have revealed inconsistent decreases in anisotropy in schizophrenia, we and others have found increased fractional anisotropy in key subcortical tracts associated with the circuits underlying symptom generation in schizophrenia. We review data revealing increased anisotropy in dopaminergic tracts in the mesencephalon of schizophrenics and their unaffected relatives, and discuss the possible biological underpinnings and physiological significance of this finding.

  10. Simulation of the passive UHF devices on the basis of high-temperature superconductors for planar multilayer anisotropic structures

    CERN Document Server

    Gashinova, M S; Kolmakov, Y A; Vendik, I B

    2002-01-01

    The electrodynamic analysis of the arbitrary multilayer medium, including the anisotropic layers and containing the arbitrary form conductors is carried out. Thin layers of the high-temperature superconductor (HTSC) are considered as conductors. Determination of the surface current density is a result of the numerical solution. Accounting for the losses in the HTSC is accomplished on the basis of determining the equivalent surface impedance and using the Leontovich boundary conditions. Anisotropy is accounted for in the determination of the Green spectral dyad for the structure with arbitrary number of the anisotropic or isotropic layers. Calculation of the surface current density distribution demonstrates the correctness of the proposed model

  11. Finding overlapping communities in multilayer networks.

    Science.gov (United States)

    Liu, Weiyi; Suzumura, Toyotaro; Ji, Hongyu; Hu, Guangmin

    2018-01-01

    Finding communities in multilayer networks is a vital step in understanding the structure and dynamics of these layers, where each layer represents a particular type of relationship between nodes in the natural world. However, most community discovery methods for multilayer networks may ignore the interplay between layers or the unique topological structure in a layer. Moreover, most of them can only detect non-overlapping communities. In this paper, we propose a new community discovery method for multilayer networks, which leverages the interplay between layers and the unique topology in a layer to reveal overlapping communities. Through a comprehensive analysis of edge behaviors within and across layers, we first calculate the similarities for edges from the same layer and the cross layers. Then, by leveraging these similarities, we can construct a dendrogram for the multilayer networks that takes both the unique topological structure and the important interplay into consideration. Finally, by introducing a new community density metric for multilayer networks, we can cut the dendrogram to get the overlapping communities for these layers. By applying our method on both synthetic and real-world datasets, we demonstrate that our method has an accurate performance in discovering overlapping communities in multilayer networks.

  12. Structural and Morphological Difference Between Ti/TiN/TiCN Coatings Grown in Multilayer and Graded Form

    International Nuclear Information System (INIS)

    Restrepo, E.; Baena, A.; Agudelo, C.; Castillo, H.; Devia, A.; Marino, A.

    2006-01-01

    Thin films can be grown in super-lattice, multilayers and graded form, having each one advantages and disadvantages. The difference between multilayer and graded coatings is the interface. In multilayers the interface is abrupt and in graded coatings it is diffuse. The interface influences many chemical and physical properties of the materials, and its choice depends on the application. Graded coatings have the advantage of having gradual properties such as thermal expansion coefficient and lattice parameter, avoiding adherence problems due to good match between their component materials. In this work the comparison between some properties of coatings grown as multilayer and graded is performed. The materials are produced using the sputtering DC technique because of its facility to control the deposition parameters and generate a slow growth. The target is a disc of titanium and the samples are made of stainless steel 304. The working gases are argon, nitrogen and methane, which are mixed according to the material to be produced, i.e. Ti layer is grown with argon, the TiN film is produced with a mixture of argon and nitrogen, and the TiCN material is obtained mixing argon, nitrogen and methane. These materials are characterized with AFM in order to determine grain size and with XPS studying the chemical composition and performing depth profiles

  13. Exposure to space radiation of high-performance infrared multilayer filters and materials technology experiments (A0056)

    Science.gov (United States)

    Seeley, J. S.; Hunneman, R.; Whatley, A.; Lipscombe, D. R.

    1984-01-01

    Infrared multilayer interface filter which were used in satellite radiometers were examined. The ability of the filters to withstand the space environment in these applications is critical. An experiment on the LDEF subjects the filters to authoritative spectral measurements following space exposure to ascertain their suitability for spacecraft use and to permit an understanding of degradation mechanisms. The understanding of the effects of prolonged space exposure on spacecraft materials, surface finishes, and adhesive systems is important to the spacecraft designer. Materials technology experiments and experiment on infrared multilayer filters are discussed.

  14. Water transport in multilayer coatings

    NARCIS (Netherlands)

    Baukh, V.

    2012-01-01

    Coatings form the interface between structures and the environment in many application domains. They play a crucial role in providing protection, e.g. against corrosion, they form a barrier against an aggressive environment and they create the aesthetic appearance. To fulfill such functionalities,

  15. Effect of Surface Tension Anisotropy and Welding Parameters on Initial Instability Dynamics During Solidification: A Phase-Field Study

    Science.gov (United States)

    Yu, Fengyi; Wei, Yanhong

    2018-05-01

    The effects of surface tension anisotropy and welding parameters on initial instability dynamics during gas tungsten arc welding of an Al-alloy are investigated by a quantitative phase-field model. The results show that the surface tension anisotropy and welding parameters affect the initial instability dynamics in different ways during welding. The surface tension anisotropy does not influence the solute diffusion process but does affect the stability of the solid/liquid interface during solidification. The welding parameters affect the initial instability dynamics by varying the growth rate and thermal gradient. The incubation time decreases, and the initial wavelength remains stable as the welding speed increases. When welding power increases, the incubation time increases and the initial wavelength slightly increases. Experiments were performed for the same set of welding parameters used in modeling, and the results of the experiments and simulations were in good agreement.

  16. QCM-D studies on polymer behavior at interfaces

    CERN Document Server

    Liu, Guangming

    2014-01-01

    QCM-D Studies on Polymer Behavior at Interfaces reviews the applications of quartz crystal microbalance with dissipation (QCM-D) in polymer research, including the conformational change of grafted polymer chains, the grafting kinetics of polymer chains, the growth mechanism of polyelectrolyte multilayers, and the interactions between polymers and phospholipid membranes. It focuses on how QCM-D can be applied to the study of polymer behavior at various solid-liquid interfaces. Moreover, it clearly reveals the physical significance of the changes in frequency and dissipation associated with the different polymer behaviors at the interfaces.

  17. Interface learning

    DEFF Research Database (Denmark)

    Thorhauge, Sally

    2014-01-01

    "Interface learning - New goals for museum and upper secondary school collaboration" investigates and analyzes the learning that takes place when museums and upper secondary schools in Denmark work together in local partnerships to develop and carry out school-related, museum-based coursework...... for students. The research focuses on the learning that the students experience in the interface of the two learning environments: The formal learning environment of the upper secondary school and the informal learning environment of the museum. Focus is also on the learning that the teachers and museum...... professionals experience as a result of their collaboration. The dissertation demonstrates how a given partnership’s collaboration affects the students’ learning experiences when they are doing the coursework. The dissertation presents findings that museum-school partnerships can use in order to develop...

  18. High Reflectance Nanoscale V/Sc Multilayer for Soft X-ray Water Window Region.

    Science.gov (United States)

    Huang, Qiushi; Yi, Qiang; Cao, Zhaodong; Qi, Runze; Loch, Rolf A; Jonnard, Philippe; Wu, Meiyi; Giglia, Angelo; Li, Wenbin; Louis, Eric; Bijkerk, Fred; Zhang, Zhong; Wang, Zhanshan

    2017-10-10

    V/Sc multilayer is experimentally demonstrated for the first time as a high reflectance mirror for the soft X-ray water window region. It primarily works at above the Sc-L edge (λ = 3.11 nm) under near normal incidence while a second peak appears at above the V-L edge (λ = 2.42 nm) under grazing incidence. The V/Sc multilayer fabricated with a d-spacing of 1.59 nm and 30 bilayers has a smaller interface width (σ = 0.27 and 0.32 nm) than the conventional used Cr/Sc (σ = 0.28 and 0.47 nm). For V/Sc multilayer with 30 bilayers, the introduction of B 4 C barrier layers has little improvement on the interface structure. As the number of bilayers increasing to 400, the growth morphology and microstructure of the V/Sc layers evolves with slightly increased crystallization. Nevertheless, the surface roughness remains to be 0.25 nm. A maximum soft X-ray reflectance of 18.4% is measured at λ = 3.129 nm at 9° off-normal incidence using the 400-bilayers V/Sc multilayer. According to the fitted model, an s-polarization reflectance of 5.2% can also be expected at λ = 2.425 nm under 40° incidence. Based on the promising experimental results, further improvement of the reflectance can be achieved by using a more stable deposition system, exploring different interface engineering methods and so on.

  19. Manipulating the magnetic anisotropy and magnetization dynamics by stress: Numerical calculation and experiment

    Science.gov (United States)

    Correa, M. A.; Bohn, F.

    2018-05-01

    We perform a theoretical and experimental investigation of the magnetic properties and magnetization dynamics of a ferromagnetic magnetostrictive multilayer grown onto a flexible substrate and submitted to external stress. We calculate the magnetic behavior and magnetoimpedance effect for a trilayered system from an approach that considers a magnetic permeability model for planar geometry and a magnetic free energy density which takes into account induced uniaxial and magnetoelastic anisotropy contributions. We verify remarkable modifications of the magnetic anisotropy with external stress, as well as we show that the dynamic magnetic response is strongly affected by these changes. We discuss the magnetic features that lead to modifications of the frequency limits where distinct mechanisms are responsible by the magnetoimpedance variations, enabling us to manipulate the resonance fields. To test the robustness of the approach, we directly compare theoretical results with experimental data. Thus, we provide experimental evidence to confirm the validity of the theoretical approach, as well as to manipulate the resonance fields to tune the MI response according to real applications in devices.

  20. Characterization of Al/Ni multilayers and their application in diffusion bonding of TiAl to TiC cermet

    International Nuclear Information System (INIS)

    Cao, J.; Song, X.G.; Wu, L.Z.; Qi, J.L.; Feng, J.C.

    2012-01-01

    The Al/Ni multilayers were characterized and diffusion bonding of TiAl intermetallics to TiC cermets was carried out using the multilayers. The microstructure of Al/Ni multilayers and TiAl/TiC cermet joint was investigated. The layered structures consisting of a Ni 3 (AlTi) layer, a Ni 2 AlTi layer, a (Ni,Al,Ti) layer and a Ni diffusion layer were observed from the interlayer to the TiAl substrate. Only one AlNi 3 layer formed at the multilayer/TiC cermet interface. The reaction behaviour of Al/Ni multilayers was characterized by means of differential scanning calorimeter (DSC) and X-ray diffraction. The initial exothermic peak of the DSC curve was formed due to the formation of Al 3 Ni and Al 3 Ni 2 phases. The reaction sequence of the Al/Ni multilayers was Al 3 Ni → Al 3 Ni 2 → AlNi → AlNi 3 and the final products were AlNi and AlNi 3 phases. The shear strength of the joint was tested and the experimental results suggested that the application of Al/Ni multilayers improved the joining quality. - Highlights: ► Diffusion bonding of TiAl to TiC cermet was realized using Al/Ni multilayer. ► The reaction sequence of the Al/Ni multilayers was Al 3 Ni → Al 3 Ni 2 → AlNi → AlNi 3 . ► The interfacial microstructure of the joint was clarified. ► The application of Al/Ni multilayers improved the joining quality.

  1. Characterization of Al/Ni multilayers and their application in diffusion bonding of TiAl to TiC cermet

    Energy Technology Data Exchange (ETDEWEB)

    Cao, J., E-mail: cao_jian@hit.edu.cn [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China); Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150001 (China); Song, X.G. [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China); Wu, L.Z. [Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150001 (China); Qi, J.L.; Feng, J.C. [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China)

    2012-02-29

    The Al/Ni multilayers were characterized and diffusion bonding of TiAl intermetallics to TiC cermets was carried out using the multilayers. The microstructure of Al/Ni multilayers and TiAl/TiC cermet joint was investigated. The layered structures consisting of a Ni{sub 3}(AlTi) layer, a Ni{sub 2}AlTi layer, a (Ni,Al,Ti) layer and a Ni diffusion layer were observed from the interlayer to the TiAl substrate. Only one AlNi{sub 3} layer formed at the multilayer/TiC cermet interface. The reaction behaviour of Al/Ni multilayers was characterized by means of differential scanning calorimeter (DSC) and X-ray diffraction. The initial exothermic peak of the DSC curve was formed due to the formation of Al{sub 3}Ni and Al{sub 3}Ni{sub 2} phases. The reaction sequence of the Al/Ni multilayers was Al{sub 3}Ni {yields} Al{sub 3}Ni{sub 2} {yields} AlNi {yields} AlNi{sub 3} and the final products were AlNi and AlNi{sub 3} phases. The shear strength of the joint was tested and the experimental results suggested that the application of Al/Ni multilayers improved the joining quality. - Highlights: Black-Right-Pointing-Pointer Diffusion bonding of TiAl to TiC cermet was realized using Al/Ni multilayer. Black-Right-Pointing-Pointer The reaction sequence of the Al/Ni multilayers was Al{sub 3}Ni {yields} Al{sub 3}Ni{sub 2} {yields} AlNi {yields} AlNi{sub 3}. Black-Right-Pointing-Pointer The interfacial microstructure of the joint was clarified. Black-Right-Pointing-Pointer The application of Al/Ni multilayers improved the joining quality.

  2. Thermoelasticity and interdiffusion in CuNi multilayers

    International Nuclear Information System (INIS)

    Benoudia, M.C.; Gao, F.; Roussel, J.M.; Labat, S.; Gailhanou, M.; Thomas, O.; Beke, D.L.; Erdelyi, Z.; Langer, G.A.; Csik, A.; Kis-Varga, M.

    2012-01-01

    Complete text of publication follows. The idea of observing artificial metallic multilayers with x-ray diffraction techniques to study interdiffusion phenomena dates back to the work of DuMond and Youtz. Interestingly, these pioneering contributions even suggested that the approach could be used to measure the concentration dependence of the diffusion coefficient. This remark is precisely the subject of the present work: we aim to revisit this issue in light of recent atomistic simulation results obtained for coherent CuNi multilayers. More generally, CuNi multilayers have been extensively studied for their magnetic, mechanical, and optical properties. These physical properties depend critically on interfaces and require a good control on the evolution of composition and strain fields under heat treatment. Understanding of how interdiffusion proceeds in these nanosystems should therefore improve these practical aspects. From a theoretical viewpoint these synthetic modulated structures have been also used as valuable model systems to test the various diffusion theories accounting in particular for the influence of the alloying energy, the coherency strain, and the local concentration. Nowadays, this field remains active and has been extended with the development of atomic simulations and many microscopy techniques like atom probe tomography which give details on the intermixing mechanisms. We have performed x-ray diffraction experiments on coherent CuNi multilayers to probe thermoelasticity and interdiffusion in these samples. Kinetic mean-field simulations combined with the modeling of the x-ray spectra were also achieved to rationalize the experimental results. We have shown that classical thermoelastic arguments combined with bulk data can be used to model the x-ray scattered intensity of annealed coherent CuNi multilayers. This result provides a valuable framework to analyze the evolution of the concentration profiles at higher temperature. The typical coherent

  3. Laser induced local modification of magnetic domain in Co/Pt multilayer

    International Nuclear Information System (INIS)

    Talapatra, A.; Mohanty, J.

    2016-01-01

    Manipulation of magnetic system by the use of laser has drawn the attention of contemporary research. We demonstrate here the modification of magnetic domain in perpendicularly magnetized Co/Pt multilayer by using ultrashort laser pulse. The as-prepared sample shows an out-of-plane saturation magnetic field of 803.4 mT and almost zero remanence with a labyrinth-like domain pattern at room temperature. Atomistic simulation showed that interaction with femto-second laser results in demagnetization of the material in 200 fs followed by a slower recovery. As it indicates a net loss in magnetization, so magnetic force microscopy is carried out to investigate the equilibrium state after the system is relaxed. Demagnetized random domains appeared at the centre of the laser spot with having a rim at the boundary which signifies a deterministic switching with respect to the neighbouring area. Rotation of domains at the central area with the application of small transverse field (100 mT) proves the region to be magnetically weaker. Systematic 3D micromagnetic simulation has been performed to model the laser induced change by selective reduction of anisotropy which is discussed in detail. This shows shrinking of domains to a near circular pattern to minimize the magnetostatic energy. 50% reduction in anisotropy energy is observed with increasing the total energy of the system and a sharp increase in demagnetization energy also takes place simultaneously. This also satisfies the anisotropy in domain rotation with the application of transverse field. - Highlights: • Laser induced magnetization dynamics. • Local manipulation of magnetic domains. • Deterministic switching of domains with laser. • Modeling magnetic domain structure with local anisotropy distribution.

  4. Laser induced local modification of magnetic domain in Co/Pt multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Talapatra, A., E-mail: ph13p1001@iith.ac.in; Mohanty, J., E-mail: jmohanty@iith.ac.in

    2016-11-15

    Manipulation of magnetic system by the use of laser has drawn the attention of contemporary research. We demonstrate here the modification of magnetic domain in perpendicularly magnetized Co/Pt multilayer by using ultrashort laser pulse. The as-prepared sample shows an out-of-plane saturation magnetic field of 803.4 mT and almost zero remanence with a labyrinth-like domain pattern at room temperature. Atomistic simulation showed that interaction with femto-second laser results in demagnetization of the material in 200 fs followed by a slower recovery. As it indicates a net loss in magnetization, so magnetic force microscopy is carried out to investigate the equilibrium state after the system is relaxed. Demagnetized random domains appeared at the centre of the laser spot with having a rim at the boundary which signifies a deterministic switching with respect to the neighbouring area. Rotation of domains at the central area with the application of small transverse field (100 mT) proves the region to be magnetically weaker. Systematic 3D micromagnetic simulation has been performed to model the laser induced change by selective reduction of anisotropy which is discussed in detail. This shows shrinking of domains to a near circular pattern to minimize the magnetostatic energy. 50% reduction in anisotropy energy is observed with increasing the total energy of the system and a sharp increase in demagnetization energy also takes place simultaneously. This also satisfies the anisotropy in domain rotation with the application of transverse field. - Highlights: • Laser induced magnetization dynamics. • Local manipulation of magnetic domains. • Deterministic switching of domains with laser. • Modeling magnetic domain structure with local anisotropy distribution.

  5. Multilayer Piezoelectric Stack Actuator Characterization

    Science.gov (United States)

    Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2008-01-01

    Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

  6. Repeatability of Cryogenic Multilayer Insulation

    Science.gov (United States)

    Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

    2017-12-01

    Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation (MLI) has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five Glenn Research Center (GRC) provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons has been fabricated by Yetispace and tested by Florida State University, the repeatability between coupons has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

  7. Multilayer heterostructures and their manufacture

    Science.gov (United States)

    Hammond, Scott R; Reese, Matthew; Rupert, Benjamin; Miedaner, Alexander; Curtis, Clavin; Olson, Dana; Ginley, David S

    2015-11-04

    A method of synthesizing multilayer heterostructures including an inorganic oxide layer residing on a solid substrate is described. Exemplary embodiments include producing an inorganic oxide layer on a solid substrate by a liquid coating process under relatively mild conditions. The relatively mild conditions include temperatures below 225.degree. C. and pressures above 9.4 mb. In an exemplary embodiment, a solution of diethyl aluminum ethoxide in anhydrous diglyme is applied to a flexible solid substrate by slot-die coating at ambient atmospheric pressure, and the diglyme removed by evaporation. An AlO.sub.x layer is formed by subjecting material remaining on the solid substrate to a relatively mild oven temperature of approximately 150.degree. C. The resulting AlO.sub.x layer exhibits relatively high light transmittance and relatively low vapor transmission rates for water. An exemplary embodiment of a flexible solid substrate is polyethylene napthalate (PEN). The PEN is not substantially adversely affected by exposure to 150.degree. C

  8. Magnetic studies of spin wave excitations in Fe/Mn multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Salhi, H. [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II de Casablanca, B.P. 5366 Mâarif, Casablanca (Morocco); LMPG, Ecole supérieure de technologie, Université Hassan de Casablanca, Casablanca (Morocco); Moubah, R.; El Bahoui, A.; Lassri, H. [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II de Casablanca, B.P. 5366 Mâarif, Casablanca (Morocco)

    2017-04-15

    The structural and magnetic properties of Fe/Mn multilayers grown by thermal evaporation technique were investigated by transmission electron microscopy, vibrating sample magnetometer and spin wave theory. Transmission electron microscopy shows that the Fe and Mn layers are continuous with a significant interfacial roughness. The magnetic properties of Fe/Mn multilayers were studied for various Fe thicknesses (t{sub Fe}). The change of magnetization as a function of temperature is well depicted by a T{sup 3/2} law. The Fe spin-wave constant was extracted and found to be larger than that reported for bulk Fe, which we attribute to the fluctuation of magnetic moments at the interface, due to the interfacial roughness. The experimental M (T) data were satisfactory fitted for multilayers with different Fe thicknesses; and several exchange interactions were extracted. - Highlights: • The structural and magnetic properties of Fe/Mn multilayers were studied. • Fe and Mn layers are continuous with an important interfacial roughness. • The Fe spin-wave constant is larger than that reported for bulk Fe due to the fluctuation of the interfacial magnetic moments.

  9. Theory of magnetoelectric effect in multilayer nanocomposites on a substrate: Resonant bending-mode response

    Directory of Open Access Journals (Sweden)

    Matthias C. Krantz

    2013-05-01

    Full Text Available Resonant bending-mode magnetoelectric (ME coefficients of magnetostrictive-piezoelectric multilayer cantilevers are calculated analytically using a model developed for arbitrary multilayers on a substrate. Without quality factor effects the ME coefficient maxima in the four-dimensional parameter space of layer numbers, layer sequences, piezoelectric volume fractions, and substrate thicknesses are found to be essentially constant for nonzero substrate thickness. Global maxima occur for bilayers without substrates. Vanishing magnetoelectric response regions result from voltage cancellation in piezoelectric layers or absence of bending-mode excitation. They are determined by the neutral plane position in the multilayer stack. With Q-factor effects dominated by viscous air damping ME coefficients strongly increase with cantilever thickness primarily due to increasing resonance frequencies. The results yield a layer specific prediction of ME coefficients, resonance frequencies, and Q-factors in arbitrary multilayers and thus distinction of linear-coupling and Q-factor effects from exchange interaction, interface, or nonlinear ME effects.

  10. Thermal analysis of continuous and patterned multilayer films in the presence of a nanoscale hot spot

    Science.gov (United States)

    Juang, Jia-Yang; Zheng, Jinglin

    2016-10-01

    Thermal responses of multilayer films play essential roles in state-of-the-art electronic systems, such as photo/micro-electronic devices, data storage systems, and silicon-on-insulator transistors. In this paper, we focus on the thermal aspects of multilayer films in the presence of a nanoscale hot spot induced by near field laser heating. The problem is set up in the scenario of heat assisted magnetic recording (HAMR), the next-generation technology to overcome the data storage density limit imposed by superparamagnetism. We characterized thermal responses of both continuous and patterned multilayer media films using transient thermal modeling. We observed that material configurations, in particular, the thermal barriers at the material layer interfaces crucially impact the temperature field hence play a key role in determining the hot spot geometry, transient response and power consumption. With a representative generic media model, we further explored the possibility of optimizing thermal performances by designing layers of heat sink and thermal barrier. The modeling approach demonstrates an effective way to characterize thermal behaviors of micro and nano-scale electronic devices with multilayer thin film structures. The insights into the thermal transport scheme will be critical for design and operations of such electronic devices.

  11. Magnetic studies of spin wave excitations in Fe/Mn multilayers

    International Nuclear Information System (INIS)

    Salhi, H.; Moubah, R.; El Bahoui, A.; Lassri, H.

    2017-01-01

    The structural and magnetic properties of Fe/Mn multilayers grown by thermal evaporation technique were investigated by transmission electron microscopy, vibrating sample magnetometer and spin wave theory. Transmission electron microscopy shows that the Fe and Mn layers are continuous with a significant interfacial roughness. The magnetic properties of Fe/Mn multilayers were studied for various Fe thicknesses (t Fe ). The change of magnetization as a function of temperature is well depicted by a T 3/2 law. The Fe spin-wave constant was extracted and found to be larger than that reported for bulk Fe, which we attribute to the fluctuation of magnetic moments at the interface, due to the interfacial roughness. The experimental M (T) data were satisfactory fitted for multilayers with different Fe thicknesses; and several exchange interactions were extracted. - Highlights: • The structural and magnetic properties of Fe/Mn multilayers were studied. • Fe and Mn layers are continuous with an important interfacial roughness. • The Fe spin-wave constant is larger than that reported for bulk Fe due to the fluctuation of the interfacial magnetic moments.

  12. Perpendicular magnetic anisotropy in CoXPd100-X alloys for magnetic tunnel junctions

    Science.gov (United States)

    Clark, B. D.; Natarajarathinam, A.; Tadisina, Z. R.; Chen, P. J.; Shull, R. D.; Gupta, S.

    2017-08-01

    CoFeB/MgO-based perpendicular magnetic tunnel junctions (p-MTJ's) with high anisotropy and low damping are critical for spin-torque transfer random access memory (STT-RAM). Most schemes of making the pinned CoFeB fully perpendicular require ferrimagnets with high damping constants, a high temperature-grown L10 alloy, or an overly complex multilayered synthetic antiferromagnet (SyAF). We report a compositional study of perpendicular CoxPd alloy-pinned Co20Fe60B20/MgO based MTJ stacks, grown at moderate temperatures in a planetary deposition system. The perpendicular anisotropy of the CoxPd alloy films can be tuned based on the layer thickness and composition. The films were characterized by alternating gradient magnetometry (AGM), energy-dispersive X-rays (EDX), and X-ray diffraction (XRD). Current-in-plane tunneling (CIPT) measurements have also been performed on the compositionally varied CoxPd MTJ stacks. The CoxPd alloy becomes fully perpendicular at approximately x = 30% (atomic fraction) Co. Full-film MTJ stacks of Si/SiO2/MgO (13)/CoXPd100-x (50)/Ta (0.3)/CoFeB (1)/MgO (1.6)/CoFeB (1)/Ta (5)/Ru (10), with the numbers enclosed in parentheses being the layer thicknesses in nm, were sputtered onto thermally oxidized silicon substrates and in-situ lamp annealed at 400 °C for 5 min. CIPT measurements indicate that the highest TMR is observed for the CoPd composition with the highest perpendicular magnetic anisotropy.

  13. Chemical reaction at ferromagnet/oxide interface and its influence on anomalous Hall effect

    International Nuclear Information System (INIS)

    Liu, Yi-Wei; Teng, Jiao; Zhang, Jing-Yan; Liu, Yang; Chen, Xi; Li, Xu-Jing; Feng, Chun; Wang, Hai-Cheng; Li, Ming-Hua; Yu, Guang-Hua; Wu, Zheng-Long

    2014-01-01

    Chemical reactions at the ferromagnet/oxide interface in [Pt/Fe] 3 /MgO and [Pt/Fe] 3 /SiO 2 multilayers before and after annealing were investigated by X-ray photoelectron spectroscopy. The results show that Fe atoms at the Fe/MgO interface were completely oxidized in the as-grown state and significantly deoxidized after vacuum annealing. However, only some of the Fe atoms at the Fe/SiO 2 interface were oxidized and rarely deoxidized after annealing. The anomalous Hall effect was modified by this interfacial chemical reaction. The saturation anomalous Hall resistance (R xy ) was greatly increased in the [Pt/Fe] 3 /MgO multilayers after annealing and was 350% higher than that in the as-deposited film, while R xy of the [Pt/Fe] 3 /SiO 2 multilayer only increased 10% after annealing.

  14. Friction Anisotropy with Respect to Topographic Orientation

    Science.gov (United States)

    Yu, Chengjiao; Wang, Q. Jane

    2012-01-01

    Friction characteristics with respect to surface topographic orientation were investigated using surfaces of different materials and fabricated with grooves of different scales. Scratching friction tests were conducted using a nano-indentation-scratching system with the tip motion parallel or perpendicular to the groove orientation. Similar friction anisotropy trends were observed for all the surfaces studied, which are (1) under a light load and for surfaces with narrow grooves, the tip motion parallel to the grooves offers higher friction coefficients than does that perpendicular to them, (2) otherwise, equal or lower friction coefficients are found under this motion. The influences of groove size relative to the diameter of the mating tip (as a representative asperity), surface contact stiffness, contact area, and the characteristic stiction length are discussed. The appearance of this friction anisotropy is independent of material; however, the boundary and the point of trend transition depend on material properties. PMID:23248751

  15. Destabilization of TAE modes by particle anisotropy

    International Nuclear Information System (INIS)

    Wong, H.V.; Berk, H.L.

    1998-01-01

    Plasmas heated by ICRF produce energetic particle distribution functions which are sharply peaked in pitch-angle, and the authors show that at moderate toroidal mode numbers, this anisotropy is a competitive and even dominant instability drive when compared with the universal instability drive due to spatial gradient. The universal drive, acting along, destabilizes only co-propagating waves (i.e., waves propagating in the same toroidal direction as the diamagnetic flow of the energetic particles), but stabilizes counter-propagating waves (i.e., waves propagating in the opposite toroidal direction as the diamagnetic flow of the energetic particles). Nonetheless, the authors show that in a tokamak, it is possible that particle anisotropy can produce a larger linear growth rate for counter-propagating waves, and provide a mechanism for preferred destabilization of the counter-propagating TAE modes that are sometimes experimentally observed

  16. Anisotropies in the cosmic microwave background: Theory

    International Nuclear Information System (INIS)

    Dodelson, S.

    1998-02-01

    Anisotropies in the Cosmic Microwave Background (CMB) contain a wealth of information about the past history of the universe and the present values of cosmological parameters. I online some of the theoretical advances of the last few years. In particular, I emphasize that for a wide class of cosmological models, theorists can accurately calculate the spectrum to better than a percent. The spectrum of anisotropies today is directly related to the pattern of inhomogeneities present at the time of recombination. This recognition leads to a powerful argument that will enable us to distinguish inflationary models from other models of structure formation. If the inflationary models turn out to be correct, the free parameters in these models will be determined to unprecedented accuracy by the upcoming satellite missions

  17. Microwave background anisotropies in quasiopen inflation

    Science.gov (United States)

    García-Bellido, Juan; Garriga, Jaume; Montes, Xavier

    1999-10-01

    Quasiopenness seems to be generic to multifield models of single-bubble open inflation. Instead of producing infinite open universes, these models actually produce an ensemble of very large but finite inflating islands. In this paper we study the possible constraints from CMB anisotropies on existing models of open inflation. The effect of supercurvature anisotropies combined with the quasiopenness of the inflating regions make some models incompatible with observations, and severely reduces the parameter space of others. Supernatural open inflation and the uncoupled two-field model seem to be ruled out due to these constraints for values of Ω0<~0.98. Others, such as the open hybrid inflation model with suitable parameters for the slow roll potential can be made compatible with observations.

  18. General quadrupolar statistical anisotropy: Planck limits

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, S. [Gran Sasso Science Institute (INFN), Viale Francesco Crispi 7, I-67100 L' Aquila (Italy); Rubtsov, G. [Institute for Nuclear Research of the Russian Academy of Sciences, Prospect of the 60th Anniversary of October 7a, 117312 Moscow (Russian Federation); Thorsrud, M. [Faculty of Engineering, Østfold University College, P.O. Box 700, 1757 Halden (Norway); Urban, F.R., E-mail: sabir.ramazanov@gssi.infn.it, E-mail: grisha@ms2.inr.ac.ru, E-mail: mikjel.thorsrud@hiof.no, E-mail: federico.urban@kbfi.ee [National Institute of Chemical Physics and Biophysics, Rävala 10, 10143 Tallinn (Estonia)

    2017-03-01

    Several early Universe scenarios predict a direction-dependent spectrum of primordial curvature perturbations. This translates into the violation of the statistical isotropy of cosmic microwave background radiation. Previous searches for statistical anisotropy mainly focussed on a quadrupolar direction-dependence characterised by a single multipole vector and an overall amplitude g {sub *}. Generically, however, the quadrupole has a more complicated geometry described by two multipole vectors and g {sub *}. This is the subject of the present work. In particular, we limit the amplitude g {sub *} for different shapes of the quadrupole by making use of Planck 2015 maps. We also constrain certain inflationary scenarios which predict this kind of more general quadrupolar statistical anisotropy.

  19. Seismic anisotropy in deforming salt bodies

    Science.gov (United States)

    Prasse, P.; Wookey, J. M.; Kendall, J. M.; Dutko, M.

    2017-12-01

    Salt is often involved in forming hydrocarbon traps. Studying salt dynamics and the deformation processes is important for the exploration industry. We have performed numerical texture simulations of single halite crystals deformed by simple shear and axial extension using the visco-plastic self consistent approach (VPSC). A methodology from subduction studies to estimate strain in a geodynamic simulation is applied to a complex high-resolution salt diapir model. The salt diapir deformation is modelled with the ELFEN software by our industrial partner Rockfield, which is based on a finite-element code. High strain areas at the bottom of the head-like strctures of the salt diapir show high amount of seismic anisotropy due to LPO development of halite crystals. The results demonstrate that a significant degree of seismic anisotropy can be generated, validating the view that this should be accounted for in the treatment of seismic data in, for example, salt diapir settings.

  20. Experimental investigation of ultrasonic velocity anisotropy in ...

    Indian Academy of Sciences (India)

    Permanent link: https://www.ias.ac.in/article/fulltext/pram/077/02/0345-0355. Keywords. Magnetic fluids; ultrasonic wave; sound velocity; anisotropy. Abstract. Magnetic field-induced dispersion of ultrasonic velocity in a Mn0.7Zn0.3Fe2O4 fluid (applied magnetic field is perpendicular to the ultrasonic propagation vector) is ...

  1. Transfer anisotropy effect in a turbulent plasma

    International Nuclear Information System (INIS)

    Bychenkov, V.Yu.; Gradov, O.M.; Silin, V.P.

    1982-01-01

    A theory is developed of transfer phenomena with pronounced ion-sound turbulence. A transfer anisotropy effect is observed which is due to the temperature gradient. The corresponding fluxes across the effective force vector generating the turbulence are found to be considerably greater than the longitudinal fluxes in a plasma with a comparatively low degree of nonisothermality. In a strongly nonisothermal plasma the suppression of transverse fluxes occurs, corresponding to the growth of thermal insulation of the current-carrying plasma filaments

  2. Ultrasonic evaluation of local human skin anisotropy

    Czech Academy of Sciences Publication Activity Database

    Tokar, Daniel; Převorovský, Zdeněk; Hradilová, Jana

    2014-01-01

    Roč. 19, č. 12 (2014) ISSN 1435-4934. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. Praha, 06.10.2014-10.10.2014] Institutional support: RVO:61388998 Keywords : anisotropy * ultrasonic testing * human skin in-vivo * fabric-fiber composite * signal processing Subject RIV: BI - Acoustics http://www.ndt.net/events/ECNDT2014/app/content/Paper/324_Tokar.pdf

  3. Anisotropy of dark matter velocity distribution

    OpenAIRE

    Nagao, Keiko I.

    2018-01-01

    Direct detection of dark matter with directional sensitivity has the potential to discriminate the dark matter velocity distribution. Especially, it will be suitable to discriminate isotropic distribution from anisotropic one. Analyzing data produced with Monte-Carlo simulation, required conditions for the discrimination is estimated. If energy threshold of detector is optimized, $O(10^3-10^4)$ event number is required to discriminate the anisotropy.

  4. Assessment of velocity anisotropy in rocks

    Czech Academy of Sciences Publication Activity Database

    Lokajíček, Tomáš; Goel, R. K.; Rudajev, Vladimír; Dwivedi, R.D.

    2013-01-01

    Roč. 57, January (2013), s. 142-152 ISSN 1365-1609 R&D Projects: GA ČR(CZ) GA205/08/0676; GA AV ČR IAA300130906; GA ČR(CZ) GAP104/12/0915 Institutional research plan: CEZ:AV0Z30130516 Keywords : elastic anisotropy * acoustic emission * uniaxial loading * hydrostatic loading Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.424, year: 2013

  5. A magneto-optic technique for studying magnetization reversal processes and anisotropies applied to Co/Cu/Co trilayer structures

    Science.gov (United States)

    Daboo, C.; Bland, J. A. C.; Hicken, R. J.; Ives, A. J. R.; Baird, M. J.; Walker, M. J.

    1993-05-01

    We report the magnetization reversal and magnetic anisotropy behavior of ultrathin Co/Cu(111)/Co (dCu=20 and 27 Å) trilayer structures prepared by MBE on a 500-Å Ge/GaAs(110) epilayer. We describe an arrangement in which the magnetization components parallel and perpendicular to the applied field are both determined from longitudinal MOKE measurements. For the samples examined, coherent rotation of the magnetization vector is observed when the magnetic field is applied along the hard in-plane anisotropy axis, with the magnitude of the magnetization vector constant and close to its bulk value. Results of micromagnetic calculations closely reproduce the observed parallel and perpendicular magnetization loops, and yield strong uniaxial magnetic anisotropies in both layers while the interlayer coupling appears to be absent or negligible in comparison with the anisotropy strengths. An absence of antiferromagnetic (AF) coupling has been observed previously [W. F. Egelhoff, Jr. and M. T. Kief, Phys. Rev. B 45, 7795 (1992)] in contrast to recent results, indicating that AF coupling [M. T. Johnson et al., Phys. Rev. Lett. 69, 969 (1992)] and GMR [D. Grieg et al., J. Magn. Magn. Mater. 110, L239 (1992)] can occur in Co/Cu(111)/Co structures grown by MBE, but these properties are sensitively dependent on growth conditions. The absence of coupling in our samples is attributed to the presence of a significant interface roughness induced by the Ge epilayer. The uniaxial anisotropies are assumed to arise from strain or defects induced in the film.

  6. Thickness dependence of magnetic anisotropy and intrinsic anomalous Hall effect in epitaxial Co{sub 2}MnAl film

    Energy Technology Data Exchange (ETDEWEB)

    Meng, K.K., E-mail: kkmeng@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Miao, J.; Xu, X.G. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhao, J.H. [State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Jiang, Y. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-04-04

    We have investigated the thickness dependence of magnetic anisotropy and intrinsic anomalous Hall effect (AHE) in single-crystalline full-Heusler alloy Co{sub 2}MnAl (CMA) grown by molecular-beam epitaxy on GaAs(001). The magnetic anisotropy is the interplay of uniaxial and the fourfold anisotropy, and the corresponding anisotropy constants have been deduced. Considering the thickness of CMA is small, we ascribe it to the influence from interface stress. The AHE in CMA is found to be well described by a proper scaling. The intrinsic anomalous conductivity is found to be smaller than the calculated one and is thickness dependent, which is ascribed to the influence of chemical ordering by affecting the band structure and Fermi surface. - Highlights: • Single-crystalline full-Heusler alloy Co{sub 2}MnAl grown by molecular-beam epitaxy. • Uniaxial and the fourfold magnetic anisotropies in Heusler alloys. • Anomalous Hall effect in Heusler alloys. • The intrinsic contributions modified by chemical ordering.

  7. Engineering functional anisotropy in fibrocartilage neotissues.

    Science.gov (United States)

    MacBarb, Regina F; Chen, Alison L; Hu, Jerry C; Athanasiou, Kyriacos A

    2013-12-01

    The knee meniscus, intervertebral disc, and temporomandibular joint (TMJ) disc all possess complex geometric shapes and anisotropic matrix organization. While these characteristics are imperative for proper tissue function, they are seldom recapitulated following injury or disease. Thus, this study's objective was to engineer fibrocartilages that capture both gross and molecular structural features of native tissues. Self-assembled TMJ discs were selected as the model system, as the disc exhibits a unique biconcave shape and functional anisotropy. To drive anisotropy, 50:50 co-cultures of meniscus cells and articular chondrocytes were grown in biconcave, TMJ-shaped molds and treated with two exogenous stimuli: biomechanical (BM) stimulation via passive axial compression and bioactive agent (BA) stimulation via chondroitinase-ABC and transforming growth factor-β1. BM + BA synergistically increased Col/WW, Young's modulus, and ultimate tensile strength 5.8-fold, 14.7-fold, and 13.8-fold that of controls, respectively; it also promoted collagen fibril alignment akin to native tissue. Finite element analysis found BM stimulation to create direction-dependent strains within the neotissue, suggesting shape plays an essential role toward driving in vitro anisotropic neotissue development. Methods used in this study offer insight on the ability to achieve physiologic anisotropy in biomaterials through the strategic application of spatial, biomechanical, and biochemical cues. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. On the limits of uniaxial magnetic anisotropy tuning by a ripple surface pattern

    Energy Technology Data Exchange (ETDEWEB)

    Arranz, Miguel A. [Facultad de Ciencias Químicas, Universidad de Castilla-La Mancha, Avda. Camilo J. Cela 10, 13071 Ciudad Real (Spain); Colino, Jose M., E-mail: josemiguel.colino@uclm.es [Instituto de Nanociencia, Nanotecnología y Materiales Moleculares, Universidad de Castilla-La Mancha, Campus de la Fábrica de Armas, 45071 Toledo (Spain); Palomares, Francisco J. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, c/ Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain)

    2014-05-14

    Ion beam patterning of a nanoscale ripple surface has emerged as a versatile method of imprinting uniaxial magnetic anisotropy (UMA) on a desired in-plane direction in magnetic films. In the case of ripple patterned thick films, dipolar interactions around the top and/or bottom interfaces are generally assumed to drive this effect following Schlömann's calculations for demagnetizing fields of an ideally sinusoidal surface [E. Schlömann, J. Appl. Phys. 41, 1617 (1970)]. We have explored the validity of his predictions and the limits of ion beam sputtering to induce UMA in a ferromagnetic system where other relevant sources of magnetic anisotropy are neglected: ripple films not displaying any evidence of volume uniaxial anisotropy and where magnetocrystalline contributions average out in a fine grain polycrystal structure. To this purpose, the surface of 100 nm cobalt films grown on flat substrates has been irradiated at fixed ion energy, fixed ion fluency but different ion densities to make the ripple pattern at the top surface with wavelength Λ and selected, large amplitudes (ω) up to 20 nm so that stray dipolar fields are enhanced, while the residual film thickness t = 35–50 nm is sufficiently large to preserve the continuous morphology in most cases. The film-substrate interface has been studied with X-ray photoemission spectroscopy depth profiles and is found that there is a graded silicon-rich cobalt silicide, presumably formed during the film growth. This graded interface is of uncertain small thickness but the range of compositions clearly makes it a magnetically dead layer. On the other hand, the ripple surface rules both the magnetic coercivity and the uniaxial anisotropy as these are found to correlate with the pattern dimensions. Remarkably, the saturation fields in the hard axis of uniaxial continuous films are measured up to values as high as 0.80 kG and obey a linear dependence on the parameter ω{sup 2}/Λ/t in quantitative

  9. Soft Interfaces

    International Nuclear Information System (INIS)

    Strzalkowski, Ireneusz

    1997-01-01

    This book presents an extended form of the 1994 Dirac Memorial Lecture delivered by Pierre Gilles de Gennes at Cambridge University. The main task of the presentation is to show the beauty and richness of structural forms and phenomena which are observed at soft interfaces between two media. They are much more complex than forms and phenomena existing in each phase separately. Problems are discussed including both traditional, classical techniques, such as the contact angle in static and dynamic partial wetting, as well as the latest research methodology, like 'environmental' scanning electron microscopes. The book is not a systematic lecture on phenomena but it can be considered as a compact set of essays on topics which particularly fascinate the author. The continuum theory widely used in the book is based on a deep molecular approach. The author is particularly interested in a broad-minded rheology of liquid systems at interfaces with specific emphasis on polymer melts. To study this, the author has developed a special methodology called anemometry near walls. The second main topic presented in the book is the problem of adhesion. Molecular processes, energy transformations and electrostatic interaction are included in an interesting discussion of the many aspects of the principles of adhesion. The third topic concerns welding between two polymer surfaces, such as A/A and A/B interfaces. Of great worth is the presentation of various unsolved, open problems. The kind of topics and brevity of description indicate that this book is intended for a well prepared reader. However, for any reader it will present an interesting picture of how many mysterious processes are acting in the surrounding world and how these phenomena are perceived by a Nobel Laureate, who won that prize mainly for his investigations in this field. (book review)

  10. Interface Screenings

    DEFF Research Database (Denmark)

    Thomsen, Bodil Marie Stavning

    2015-01-01

    In Wim Wenders' film Until the End of the World (1991), three different diagrams for the visual integration of bodies are presented: 1) GPS tracking and mapping in a landscape, 2) video recordings layered with the memory perception of these recordings, and 3) data-created images from dreams...... and memories. From a transvisual perspective, the question is whether or not these (by now realized) diagrammatic modes involving the body in ubiquitous global media can be analysed in terms of the affects and events created in concrete interfaces. The examples used are filmic as felt sensations...

  11. The confinement of phonon propagation in TiAlN/Ag multilayer coatings with anomalously low heat conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Kovalev, A. I.; Wainstein, D. L., E-mail: d-wainstein@sprg.ru [Surface Phenomena Researches Group, Radio Str., 23/9, Bld. 2, Off. 475, CNIICHERMET, 105005 Moscow (Russian Federation); Rashkovskiy, A. Yu. [Surface Phenomena Researches Group, Radio Str., 23/9, Bld. 2, Off. 475, CNIICHERMET, 105005 Moscow (Russian Federation); National University of Science and Technology MISiS, Leninskiy pr-t, 4, 119049 Moscow (Russian Federation); Gago, R. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, E-28049 Madrid (Spain); Soldera, F. [Department of Materials Science and Engineering, Saarland University, 66123 Saarbruecken (Germany); Endrino, J. L. [School of Aerospace, Transport and Manufacturing (SATM), Surface Engineering and Nanotechnology Institute, Cranfield University, College Road, Cranfield, MK43 0AL Bedfordshire (United Kingdom)

    2016-05-30

    TiAlN/Ag multilayer coatings with a different number of bilayers and thicknesses of individual layers were fabricated by DC magnetron co-sputtering. Thermal conductivity was measured in dependence of Ag layer thickness. It was found anomalous low thermal conductivity of silver comparing to TiAlN and Ag bulk standards and TiAlN/TiN multilayers. The physical nature of such thermal barrier properties of the multilayer coatings was explained on the basis of reflection electron energy loss spectroscopy. The analysis shows that nanostructuring of the coating decreases the density of states and velocity of acoustic phonons propagation. At the same time, multiphonon channels of heat propagation degenerate. These results demonstrate that metal-dielectric interfaces in TiAlN/Ag coatings are insurmountable obstacles for acoustic phonons propagation.

  12. What does anisotropy measure? Insights from increased and decreased anisotropy in selective fiber tracts in schizophrenia.

    Science.gov (United States)

    Alba-Ferrara, L M; de Erausquin, Gabriel A

    2013-01-01

    Schizophrenia is a common, severe, and chronically disabling mental illness of unknown cause. Recent MRI studies have focused attention on white matter abnormalities in schizophrenia using diffusion tensor imaging (DTI). Indices commonly derived from DTI include (1) mean diffusivity, independent of direction, (2) fractional anisotropy (FA) or relative anisotropy (RA), (3) axial diffusivity, and (4) radial diffusivity. In cerebral white matter, contributions to these indices come from fiber arrangements, degree of myelination, and axonal integrity. Relatively pure deficits in myelin result in a modest increase in radial diffusivity, without affecting axial diffusivity and with preservation of anisotropy. Although schizophrenia is not characterized by gross abnormalities of white matter, it does involve a profound dysregulation of myelin-associated gene expression, reductions in oligodendrocyte numbers, and marked abnormalities in the ultrastructure of myelin sheaths. Since each oligodendrocyte myelinates as many as 40 axon segments, changes in the number of oligodendrocytes (OLG), and/or in the integrity of myelin sheaths, and/or axoglial contacts can have a profound impact on signal propagation and the integrity of neuronal circuits. Whereas a number of studies have revealed inconsistent decreases in anisotropy in schizophrenia, we and others have found increased FA in key subcortical tracts associated with the circuits underlying symptom generation in schizophrenia. We review data revealing increased anisotropy in dopaminergic tracts in the mesencephalon of schizophrenics and their unaffected relatives, and discuss the possible biological underpinnings and physiological significance of this finding.

  13. Influence of modulation periods on the tribological behavior of Si/a-C: H multilayer film

    Science.gov (United States)

    Zhu, Linan; Wu, Yanxia; Zhang, Shujiao; Yu, Shengwang; Tang, Bin; Liu, Ying; Zhou, Bing; Shen, Yanyan

    2018-01-01

    A series of Si/a-C: H multilayer films with different modulation periods were fabricated on stainless steel and silicon substrates by radio-frequency magnetron sputtering. The influence of the modulation period on the structure, morphology, mechanical properties and tribological behaviors in different environments (air, simulated acid rain, and NaCl solution) was investigated. The results show that the content of the sp2 hybrid carbon, surface roughness and hardness of the multilayer film increased firstly and then decreased with the decreased modulation period. Furthermore, the combination of the sublayer agrees well with the formation of the SiC crystal at the interface. Interestingly, the films show quite substantially different tribological properties in various test environments. The lowest friction coefficient is 0.2 for the S1 film in air. However, the lowest friction coefficient can reach 0.13 in solution. Importantly, the tribological behavior of the multilayer film is mainly determined by its hardness, as well as surface roughness in air while it is closely related with modulation period and interface structure in solution.

  14. 18O-tracer diffusion along nanoscaled Sc2O3/yttria stabilized zirconia (YSZ multilayers: on the influence of strain

    Directory of Open Access Journals (Sweden)

    Halit Aydin, Carsten Korte and Jürgen Janek

    2013-01-01

    Full Text Available The oxygen tracer diffusion coefficient describing transport along nano-/microscaled YSZ/Sc2O3 multilayers as a function of the thick­ness of the ion-conducting YSZ layers has been measured by isotope exchange depth profiling (IEDP, using secondary ion mass spec­trometry (SIMS. The multilayer samples were prepared by pulsed laser deposition (PLD on (0001 Al2O3 single crystalline substrates. The values for the oxygen tracer diffusion coefficient were analyzed as a combination of contributions from bulk and interface contributions and compared with results from YSZ/Y2O3-multilayers with similar microstructure. Using the Nernst–Einstein equation as the relation between diffusivity and electrical conductivity we find very good agreement between conductivity and diffusion data, and we exclude substantial electronic conductivity in the multilayers. The effect of hetero-interface transport can be well explained by a simple interface strain model. As the multilayer samples consist of columnar film crystallites with a defined inter­face structure and texture, we also discuss the influence of this particular microstructure on the interfacial strain.

  15. Base Metal Co-Fired Multilayer Piezoelectrics

    Directory of Open Access Journals (Sweden)

    Lisheng Gao

    2016-03-01

    Full Text Available Piezoelectrics have been widely used in different kinds of applications, from the automobile industry to consumer electronics. The novel multilayer piezoelectrics, which are inspired by multilayer ceramic capacitors, not only minimize the size of the functional parts, but also maximize energy efficiency. Development of multilayer piezoelectric devices is at a significant crossroads on the way to achieving low costs, high efficiency, and excellent reliability. Concerning the costs of manufacturing multilayer piezoelectrics, the trend is to replace the costly noble metal internal electrodes with base metal materials. This paper discusses the materials development of metal co-firing and the progress of integrating current base metal chemistries. There are some significant considerations in metal co-firing multilayer piezoelectrics: retaining stoichiometry with volatile Pb and alkaline elements in ceramics, the selection of appropriate sintering agents to lower the sintering temperature with minimum impact on piezoelectric performance, and designing effective binder formulation for low pO2 burnout to prevent oxidation of Ni and Cu base metal.

  16. Corrugated grating on organic multilayer Bragg reflector

    Science.gov (United States)

    Jaquet, Sylvain; Scharf, Toralf; Herzig, Hans Peter

    2007-08-01

    Polymeric multilayer Bragg structures are combined with diffractive gratings to produce artificial visual color effects. A particular effect is expected due to the angular reflection dependence of the multilayer Bragg structure and the dispersion caused by the grating. The combined effects can also be used to design particular filter functions and various resonant structures. The multilayer Bragg structure is fabricated by spin-coating of two different low-cost polymer materials in solution on a cleaned glass substrate. These polymers have a refractive index difference of about 0.15 and permit multilayer coatings without interlayer problems. Master gratings of different periods are realized by laser beam interference and replicated gratings are superimposed on the multilayer structure by soft embossing in a UV curing glue. The fabrication process requires only polymer materials. The obtained devices are stable and robust. Angular dependent reflection spectrums for the visible are measured. These results show that it is possible to obtain unexpected reflection effects. A rich variety of color spectra can be generated, which is not possible with a single grating. This can be explained by the coupling of transmission of grating orders and the Bragg reflection band. A simple model permits to explain some of the spectral vs angular dependence of reflected light.

  17. Magnetic surfaces, thin films, and multilayers

    International Nuclear Information System (INIS)

    Parkin, S.S.P.; Renard, J.P.; Shinjo, T.; Zinn, W.

    1992-01-01

    This paper details recent developments in the magnetism of surfaces, thin films and multilayers. More than 20 invited contributions and more than 60 contributed papers attest to the great interest and vitality of this subject. In recent years the study of magnetic surfaces, thin films and multilayers has undergone a renaissance, partly motivated by the development of new growth and characterization techniques, but perhaps more so by the discovery of many exciting new properties, some quite unanticipated. These include, most recently, the discovery of enormous values of magnetoresistance in magnetic multilayers far exceeding those found in magnetic single layer films and the discovery of oscillatory interlayer coupling in transition metal multilayers. These experimental studies have motivated much theoretical work. However these developments are to a large extent powered by materials engineering and our ability to control and understand the growth of thin layers just a few atoms thick. The preparation of single crystal thin film layers and multilayers remains important for many studies, in particular, for properties dependent. These studies obviously require engineering not just a layer thicknesses but of lateral dimensions as well. The properties of such structures are already proving to be a great interest

  18. Out-of-plane spin-orientation dependent magnetotransport properties in the anisotropic helimagnet CR1/3NbS2 [Spin-Orbit Coupling Induced Anisotropy in the Magnetotransport of the Chiral Helimagnet Cr1=3NbS2

    International Nuclear Information System (INIS)

    Bornstein, Alexander C.; Chapman, Benjamin J.; Ghimire, Nirmal J.; Oak Ridge National Lab.; Technology Div.); Mandrus, David G.; Oak Ridge National Lab.; Technology Div.); Parker, David S.; Technology Div.); Lee, Minhyea

    2015-01-01

    Understanding the role of spin-orbit coupling (SOC) has been crucial for controlling magnetic anisotropy in magnetic multilayer films. It has been shown that electronic structure can be altered via interface SOC by varying the superlattice structure, resulting in spontaneous magnetization perpendicular or parallel to the plane. In lieu of magnetic thin films, we study the similarly anisotropic helimagnet Cr1/3NbS2 where the spin-polarization direction, controlled by the applied magnetic field, can modify the electronic structure. As a result, the direction of spin polarization can modulate the density of states and in turn affect the in-plane electrical conductivity. In Cr1/3NbS2, we found an enhancement of in-plane conductivity when the spin polarization is out-of-plane as compared to in-plane spin polarization. This is consistent with the increase in density of states near the Fermi energy at the same spin configuration, found from first-principles calculations. We also observe unusual field dependence of the Hall signal in the same temperature range. This is unlikely to originate from the noncollinear spin texture but rather further indicates strong dependence of electronic structure on spin orientation relative to the plane

  19. Chemically mediated diffusion of d-metals and B through Si and agglomeration at Si-on-Mo interfaces

    NARCIS (Netherlands)

    T. Tsarfati,; Zoethout, E.; van de Kruijs, R.; F. Bijkerk,

    2009-01-01

    Chemical diffusion and interlayer formation in thin layers and at interfaces is of increasing influence in nanoscopic devices, such as nanoelectronics and reflective multilayer optics. Chemical diffusion and agglomeration at interfaces of thin Ru, Mo, Si, and B4C layers have been studied with x-ray

  20. Thermodynamic and kinetic anisotropies in octane thin films

    Energy Technology Data Exchange (ETDEWEB)

    Haji-Akbari, Amir; Debenedetti, Pablo G., E-mail: pdebene@exchange.princeton.edu [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2015-12-07

    Confinement breaks the translational symmetry of materials, making all thermodynamic and kinetic quantities functions of position. Such symmetry breaking can be used to obtain configurations that are not otherwise accessible in the bulk. Here, we use computer simulations to explore the effect of substrate-liquid interactions on thermodynamic and kinetic anisotropies induced by a solid substrate. We consider n-octane nano-films that are in contact with substrates with varying degrees of attraction, parameterized by an interaction parameter ϵ{sub S}. Complete freezing of octane nano-films is observed at low temperatures, irrespective of ϵ{sub S}, while at intermediate temperatures, a frozen monolayer emerges at solid-liquid and vapor-liquid interfaces. By carefully inspecting the profiles of translational and orientational relaxation times, we confirm that the translational and orientational degrees of freedom are decoupled at these frozen monolayers. At sufficiently high temperatures, however, free interfaces and solid-liquid interfaces close to loose (low-ϵ{sub S}) substrates undergo “pre-freezing,” characterized by mild peaks in several thermodynamic quantities. Two distinct dynamic regimes are observed at solid-liquid interfaces. The dynamics is accelerated in the vicinity of loose substrates, while sticky (high-ϵ{sub S}) substrates decelerate dynamics, sometimes by as much as two orders of magnitude. These two distinct dynamical regimes have been previously reported by Haji-Akbari and Debenedetti [J. Chem. Phys. 141, 024506 (2014)] for a model atomic glass-forming liquid. We also confirm the existence of two correlations—proposed in the above-mentioned work—in solid-liquid subsurface regions of octane thin films, i.e., a correlation between atomic density and normal stress, and between atomic translational relaxation time and lateral stress. Finally, we inspect the ability of different regions of an octane film to explore the potential energy

  1. Thermodynamic and kinetic anisotropies in octane thin films.

    Science.gov (United States)

    Haji-Akbari, Amir; Debenedetti, Pablo G

    2015-12-07

    Confinement breaks the translational symmetry of materials, making all thermodynamic and kinetic quantities functions of position. Such symmetry breaking can be used to obtain configurations that are not otherwise accessible in the bulk. Here, we use computer simulations to explore the effect of substrate-liquid interactions on thermodynamic and kinetic anisotropies induced by a solid substrate. We consider n-octane nano-films that are in contact with substrates with varying degrees of attraction, parameterized by an interaction parameter ϵS. Complete freezing of octane nano-films is observed at low temperatures, irrespective of ϵS, while at intermediate temperatures, a frozen monolayer emerges at solid-liquid and vapor-liquid interfaces. By carefully inspecting the profiles of translational and orientational relaxation times, we confirm that the translational and orientational degrees of freedom are decoupled at these frozen monolayers. At sufficiently high temperatures, however, free interfaces and solid-liquid interfaces close to loose (low-ϵS) substrates undergo "pre-freezing," characterized by mild peaks in several thermodynamic quantities. Two distinct dynamic regimes are observed at solid-liquid interfaces. The dynamics is accelerated in the vicinity of loose substrates, while sticky (high-ϵS) substrates decelerate dynamics, sometimes by as much as two orders of magnitude. These two distinct dynamical regimes have been previously reported by Haji-Akbari and Debenedetti [J. Chem. Phys. 141, 024506 (2014)] for a model atomic glass-forming liquid. We also confirm the existence of two correlations-proposed in the above-mentioned work-in solid-liquid subsurface regions of octane thin films, i.e., a correlation between atomic density and normal stress, and between atomic translational relaxation time and lateral stress. Finally, we inspect the ability of different regions of an octane film to explore the potential energy landscape by performing inherent

  2. Thermodynamic and kinetic anisotropies in octane thin films

    International Nuclear Information System (INIS)

    Haji-Akbari, Amir; Debenedetti, Pablo G.

    2015-01-01

    Confinement breaks the translational symmetry of materials, making all thermodynamic and kinetic quantities functions of position. Such symmetry breaking can be used to obtain configurations that are not otherwise accessible in the bulk. Here, we use computer simulations to explore the effect of substrate-liquid interactions on thermodynamic and kinetic anisotropies induced by a solid substrate. We consider n-octane nano-films that are in contact with substrates with varying degrees of attraction, parameterized by an interaction parameter ϵ S . Complete freezing of octane nano-films is observed at low temperatures, irrespective of ϵ S , while at intermediate temperatures, a frozen monolayer emerges at solid-liquid and vapor-liquid interfaces. By carefully inspecting the profiles of translational and orientational relaxation times, we confirm that the translational and orientational degrees of freedom are decoupled at these frozen monolayers. At sufficiently high temperatures, however, free interfaces and solid-liquid interfaces close to loose (low-ϵ S ) substrates undergo “pre-freezing,” characterized by mild peaks in several thermodynamic quantities. Two distinct dynamic regimes are observed at solid-liquid interfaces. The dynamics is accelerated in the vicinity of loose substrates, while sticky (high-ϵ S ) substrates decelerate dynamics, sometimes by as much as two orders of magnitude. These two distinct dynamical regimes have been previously reported by Haji-Akbari and Debenedetti [J. Chem. Phys. 141, 024506 (2014)] for a model atomic glass-forming liquid. We also confirm the existence of two correlations—proposed in the above-mentioned work—in solid-liquid subsurface regions of octane thin films, i.e., a correlation between atomic density and normal stress, and between atomic translational relaxation time and lateral stress. Finally, we inspect the ability of different regions of an octane film to explore the potential energy landscape by performing

  3. Multilayer cladding with hyperbolic dispersion for plasmonic waveguides

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Shalaginov, Mikhail Y.; Ishii, Satoshi

    2015-01-01

    We study the properties of plasmonic waveguides with a dielectric core and multilayer metal-dielectric claddings that possess hyperbolic dispersion. The waveguides hyperbolic multilayer claddings show better performance in comparison to conventional plasmonic waveguides. © OSA 2015....

  4. Multilayer Integrated Film Bulk Acoustic Resonators

    CERN Document Server

    Zhang, Yafei

    2013-01-01

    Multilayer Integrated Film Bulk Acoustic Resonators mainly introduces the theory, design, fabrication technology and application of a recently developed new type of device, multilayer integrated film bulk acoustic resonators, at the micro and nano scale involving microelectronic devices, integrated circuits, optical devices, sensors and actuators, acoustic resonators, micro-nano manufacturing, multilayer integration, device theory and design principles, etc. These devices can work at very high frequencies by using the newly developed theory, design, and fabrication technology of nano and micro devices. Readers in fields of IC, electronic devices, sensors, materials, and films etc. will benefit from this book by learning the detailed fundamentals and potential applications of these advanced devices. Prof. Yafei Zhang is the director of the Ministry of Education’s Key Laboratory for Thin Films and Microfabrication Technology, PRC; Dr. Da Chen was a PhD student in Prof. Yafei Zhang’s research group.

  5. Enhancement of surface mechanical properties by using TiN[BCN/BN]{sub n}/c-BN multilayer system

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, H. [Laboratorio de Recubrimientos Duros, CDT-ASTIN SENA, Cali (Colombia); Caicedo, J.C., E-mail: Jcesarca@calima.univalle.edu.co [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Amaya, C. [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Munoz-Saldana, J. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Mexico (Mexico); Yate, L.; Esteve, J. [Department de Fisica Aplicada i Optica, Universitat de Barcelona, Catalunya (Spain); Prieto, P. [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Centro de Excelencia en Nuevos Materiales, CENM, Cali (Colombia)

    2010-11-15

    The aim of this work is to improve the mechanical properties of AISI 4140 steel substrates by using a TiN[BCN/BN]{sub n}/c-BN multilayer system as a protective coating. TiN[BCN/BN]{sub n}/c-BN multilayered coatings via reactive r.f. magnetron sputtering technique were grown, systematically varying the length period ({Lambda}) and the number of bilayers (n) because one bilayer (n = 1) represents two different layers (t{sub BCN} + t{sub BN}), thus the total thickness of the coating and all other growth parameters were maintained constant. The coatings were characterized by Fourier transform infrared spectroscopy showing bands associated with h-BN bonds and c-BN stretching vibrations centered at 1400 cm{sup -1} and 1100 cm{sup -1}, respectively. Coating composition and multilayer modulation were studied via secondary ion mass spectroscopy. Atomic force microscopy analysis revealed a reduction in grain size and roughness when the bilayer number (n) increased and the bilayer period decreased. Finally, enhancement of mechanical properties was determined via nanoindentation measurements. The best behavior was obtained when the bilayer period ({Lambda}) was 80 nm (n = 25), yielding the relative highest hardness ({approx}30 GPa) and elastic modulus (230 GPa). The values for the hardness and elastic modulus are 1.5 and 1.7 times greater than the coating with n = 1, respectively. The enhancement effects in multilayered coatings could be attributed to different mechanisms for layer formation with nanometric thickness due to the Hall-Petch effect; because this effect, originally used to explain increased hardness with decreasing grain size in bulk polycrystalline metals, has also been used to explain hardness enhancements in multilayered coatings taking into account the thickness reduction at individual single layers that make up the multilayered system. The Hall-Petch model based on dislocation motion within layered and across layer interfaces has been successfully applied to

  6. Enhancement of surface mechanical properties by using TiN[BCN/BN] n/c-BN multilayer system

    Science.gov (United States)

    Moreno, H.; Caicedo, J. C.; Amaya, C.; Muñoz-Saldaña, J.; Yate, L.; Esteve, J.; Prieto, P.

    2010-11-01

    The aim of this work is to improve the mechanical properties of AISI 4140 steel substrates by using a TiN[BCN/BN] n/c-BN multilayer system as a protective coating. TiN[BCN/BN] n/c-BN multilayered coatings via reactive r.f. magnetron sputtering technique were grown, systematically varying the length period ( Λ) and the number of bilayers ( n) because one bilayer ( n = 1) represents two different layers ( tBCN + tBN), thus the total thickness of the coating and all other growth parameters were maintained constant. The coatings were characterized by Fourier transform infrared spectroscopy showing bands associated with h-BN bonds and c-BN stretching vibrations centered at 1400 cm -1 and 1100 cm -1, respectively. Coating composition and multilayer modulation were studied via secondary ion mass spectroscopy. Atomic force microscopy analysis revealed a reduction in grain size and roughness when the bilayer number ( n) increased and the bilayer period decreased. Finally, enhancement of mechanical properties was determined via nanoindentation measurements. The best behavior was obtained when the bilayer period ( Λ) was 80 nm ( n = 25), yielding the relative highest hardness (˜30 GPa) and elastic modulus (230 GPa). The values for the hardness and elastic modulus are 1.5 and 1.7 times greater than the coating with n = 1, respectively. The enhancement effects in multilayered coatings could be attributed to different mechanisms for layer formation with nanometric thickness due to the Hall-Petch effect; because this effect, originally used to explain increased hardness with decreasing grain size in bulk polycrystalline metals, has also been used to explain hardness enhancements in multilayered coatings taking into account the thickness reduction at individual single layers that make up the multilayered system. The Hall-Petch model based on dislocation motion within layered and across layer interfaces has been successfully applied to multilayered coatings to explain this

  7. Enhancement of surface mechanical properties by using TiN[BCN/BN]n/c-BN multilayer system

    International Nuclear Information System (INIS)

    Moreno, H.; Caicedo, J.C.; Amaya, C.; Munoz-Saldana, J.; Yate, L.; Esteve, J.; Prieto, P.

    2010-01-01

    The aim of this work is to improve the mechanical properties of AISI 4140 steel substrates by using a TiN[BCN/BN] n /c-BN multilayer system as a protective coating. TiN[BCN/BN] n /c-BN multilayered coatings via reactive r.f. magnetron sputtering technique were grown, systematically varying the length period (Λ) and the number of bilayers (n) because one bilayer (n = 1) represents two different layers (t BCN + t BN ), thus the total thickness of the coating and all other growth parameters were maintained constant. The coatings were characterized by Fourier transform infrared spectroscopy showing bands associated with h-BN bonds and c-BN stretching vibrations centered at 1400 cm -1 and 1100 cm -1 , respectively. Coating composition and multilayer modulation were studied via secondary ion mass spectroscopy. Atomic force microscopy analysis revealed a reduction in grain size and roughness when the bilayer number (n) increased and the bilayer period decreased. Finally, enhancement of mechanical properties was determined via nanoindentation measurements. The best behavior was obtained when the bilayer period (Λ) was 80 nm (n = 25), yielding the relative highest hardness (∼30 GPa) and elastic modulus (230 GPa). The values for the hardness and elastic modulus are 1.5 and 1.7 times greater than the coating with n = 1, respectively. The enhancement effects in multilayered coatings could be attributed to different mechanisms for layer formation with nanometric thickness due to the Hall-Petch effect; because this effect, originally used to explain increased hardness with decreasing grain size in bulk polycrystalline metals, has also been used to explain hardness enhancements in multilayered coatings taking into account the thickness reduction at individual single layers that make up the multilayered system. The Hall-Petch model based on dislocation motion within layered and across layer interfaces has been successfully applied to multilayered coatings to explain this

  8. Evolution of structure with Fe layer thickness in low dimensional Fe/Tb multilayered structures

    International Nuclear Information System (INIS)

    Harris, V.G.; Aylesworth, K.D.; Elam, W.T.; Koon, N.C.; Coehoorn, R.; Hoving, W.

    1992-01-01

    This paper reports on the atomic structure of a series of low-dimensional Fe/Tb multilayered structures which has been explored using a conversion-electron, extended x-ray absorption fine structure (EXAFS) technique. A structural transition from a close-packed amorphous structure to a body-centered crystalline structure is detected to occur over an Fe layer thickness range of 12.5 Angstrom to 15.0 Angstrom (Tb thickness is held constant at 4.5 Angstrom). Magnetic properties, specifically, magnetization, anisotropy field, and Kerr rotation angle, are measured and found to change significantly in response to this transition. Exploitation of the polarization properties of synchrotron radiation allowed for the description of the atomic structure both perpendicular and parallel to the sample plane

  9. Effects of Various Passivation Layers on Electrical Properties of Multilayer MoS₂ Transistors.

    Science.gov (United States)

    Ma, Jiyeon; Yoo, Geonwook

    2018-09-01

    So far many of research on transition metal dichalcogenides (TMDCs) are based on a bottomgate device structure due to difficulty with depositing a dielectric film on top of TMDs channel layer. In this work, we study different effects of various passivation layers on electrical properties of multilayer MoS2 transistors: spin-coated CYTOP, SU-8, and thermal evaporated MoOX. The SU-8 passivation layer alters device performance least significantly, and MoOX induces positive threshold voltage shift of ~8.0 V due to charge depletion at the interface, and the device with CYTOP layer exhibits decreased field-effect mobility by ~50% due to electric dipole field effect of C-F bonds in the end groups. Our results imply that electrical properties of the multilayer MoS2 transistors can be modulated using a passivation layer, and therefore a proper passivation layer should be considered for MoS2 device structures.

  10. Multi-layer composite structure covered polytetrafluoroethylene for visible-infrared-radar spectral Compatibility

    Science.gov (United States)

    Qi, Dong; Cheng, Yongzhi; Wang, Xian; Wang, Fang; Li, Bowen; Gong, Rongzhou

    2017-12-01

    In this paper, a polytetrafluoroethylene (PTFE) top-covered multi-layer composite structure PTFE/H s/(Ge/ZnS)3 (H s represents the surface layer ZnS with various thicknesses) for spectral compatibility is proposed and investigated theoretically and experimentally. A substantial decline of glossiness from over 200 Gs to 74.2 Gs could be realized, due to high roughness and interface reflection of the 800 nm PTFE protection layer. In addition, similar to the structure of H s/(Ge/ZnS)3, the designed structure with a certain color exhibits ultra-low emissivity of average 0.196 at 8-14 µm and highly transparent performance of 96.45% in the radar frequency range of 2-18 GHz. Our design will provide an important reference for the practical applications of the spectral compatible multilayer films.

  11. Solid-state reaction in Fe/V multilayers by ion beam mixing with thermal annealing

    International Nuclear Information System (INIS)

    Borges, J.F.M.; Costa, M.I. da Jr.; Teixeira, S.R.; Cunha, J.B.M. da; Alves, M.C.M.

    2001-01-01

    We report a study on the structural and magnetic properties of iron-vanadium thin films, originally grown in multilayer form [Fe(20 A)/V(20 A)] 20 , and mixed by ion beam mixing (IBM) and a subsequent thermal treatment. The samples were structurally characterised by X-ray diffraction (XRD) in the θ-2θ geometry and X-ray absorption spectroscopy (XAS). The magnetic characterisation was made using conversion electron Moessbauer spectroscopy (CEMS). The XRD result for the as-deposited multilayer shows a high-degree crystallinity, while CEMS suggests abrupt interface, since no significant contribution from vanadium in iron is observed. After the IBM and thermal treatment, the results from XRD show an FeV solid solution indexed as a bcc-disordered structure (α phase). XAS structural results are consistent with the XRD observations. CEMS results show a magnetic moment reduction for mixed samples

  12. Low-threshold optical bistability with multilayer graphene-covering Otto configuration

    International Nuclear Information System (INIS)

    Wang, Hengliang; Wu, Jipeng; Xiang, Yuanjiang; Wen, Shuangchun; Guo, Jun; Jiang, Leyong

    2016-01-01

    In this paper, we propose a modified Otto configuration to realize tunable and low-threshold optical bistability at terahertz frequencies by attaching multilayer graphene sheets to a nonlinear substrate interface. Our work demonstrates that the threshold of optical bistability can be markedly reduced (three orders of magnitude) by covering the nonlinear substrate with multilayer graphene sheets, due to strong local field enhancement with the excitation of surface plasmons. We present the influences of the Fermi energy of graphene, the incident angle, the thickness of air gap and the relaxation time of graphene on the hysteresis phenomenon and give a way to optimize the surface plasmon resonance, which will enable us to further lower the minimal power requirements for realizing optical bistability due to the strong interaction of light with graphene sheets. These results are promising for realization of terahertz optical switches, optical modulators and logical devices. (paper)

  13. Assessment of Theories for Free Vibration Analysis of Homogeneous and Multilayered Plates

    Directory of Open Access Journals (Sweden)

    Erasmo Carrera

    2004-01-01

    Full Text Available This paper assesses classical and advanced theories for free vibrational response of homogeneous and multilayered simply supported plates. Closed form solutions are given for thick and thin geometries. Single layer and multilayered plates made of metallic, composite and piezo-electric materials, are considered. Classical theories based on Kirchhoff and Reissner-Mindlin assumptions are compared with refined theories obtained by enhancing the order of the expansion of the displacement fields in the thickness direction z. The effect of the Zig-Zag form of the displacement distribution in z as well as of the Interlaminar Continuity of transverse shear and normal stresses at the layer interface were evaluated. A number of conclusions have been drawn. These conclusions could be used as desk-bed in order to choose the most valuable theories for a given problem.

  14. Optical properties of metallic multi-layer films

    International Nuclear Information System (INIS)

    Dimmich, R.

    1991-09-01

    Optical properties of multi-layer films consisting of alternating layers of two different metals are studied on the basis of the Maxwell equations and the Boltzmann transport theory. The influence of free-electron scattering at the film external surface and at the interfaces is taken into account and considered as a function of the electromagnetic field frequency and the structure modulation wavelength. Derived formulas for optical coefficients are valid at low frequencies, where the skin effect is nearly classical, as well as in the near-infrared, visible and ultraviolet spectral ranges, where the skin effect has the anomalous nature. It is shown that the obtained results are apparently dependent on the values of the scattering parameters. What is more, the oscillatory nature of analyzed spectra is observed, where the two oscillation periods may appear on certain conditions. The oscillations result from the electron surface and interface scattering and their amplitudes and periods depend on the boundary conditions for free-electron scattering. Finally, the application of the interference phenomenon in dielectric layers is proposed to obtain the enhancement of the non distinct details which can appear in optical spectra of metallic films. (author). 31 refs, 6 figs

  15. Transitional inertialess instabilities in driven multilayer channel flows

    Science.gov (United States)

    Papaefthymiou, Evangelos; Papageorgiou, Demetrios

    2016-11-01

    We study the nonlinear stability of viscous, immiscible multilayer flows in channels driven both by a pressure gradient and/or gravity in a slightly inclined channel. Three fluid phases are present with two internal interfaces. Novel weakly nonlinear models of coupled evolution equations are derived and we concentrate on inertialess flows with stably stratified fluids, with and without surface tension. These are 2 × 2 systems of second-order semilinear parabolic PDEs that can exhibit inertialess instabilities due to resonances between the interfaces - mathematically this is manifested by a transition from hyperbolic to elliptic behavior of the nonlinear flux functions. We consider flows that are linearly stable (i.e the nonlinear fluxes are hyperbolic initially) and use the theory of nonlinear systems of conservation laws to obtain a criterion (which can be verified easily) that can predict nonlinear stability or instability (i.e. nonlinear fluxes encounter ellipticity as they evolve spatiotemporally) at large times. In the former case the solution decays asymptotically to its base state, and in the latter nonlinear traveling waves emerge. EPSRC Grant Numbers EP/K041134 and EP/L020564.

  16. Optical phonons in PbTe/CdTe multilayer heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Novikova, N. N.; Yakovlev, V. A. [Russian Academy of Sciences, Institute for Spectroscopy (Russian Federation); Kucherenko, I. V., E-mail: kucheren@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Karczewski, G. [Polish Academy of Sciences, Institute of Physics (Poland); Aleshchenko, Yu. A.; Muratov, A. V.; Zavaritskaya, T. N.; Melnik, N. N. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2015-05-15

    The infrared reflection spectra of PbTe/CdTe multilayer nanostructures grown by molecular-beam epitaxy are measured in the frequency range of 20–5000 cm{sup −1} at room temperature. The thicknesses and high-frequency dielectric constants of the PbTe and CdTe layers and the frequencies of the transverse optical (TO) phonons in these structures are determined from dispersion analysis of the spectra. It is found that the samples under study are characterized by two TO phonon frequencies, equal to 28 and 47 cm{sup −1}. The first frequency is close to that of TO phonons in bulk PbTe, and the second is assigned to the optical mode in structurally distorted interface layers. The Raman-scattering spectra upon excitation with the radiation of an Ar{sup +} laser at 514.5 nm are measured at room and liquid-nitrogen temperatures. The weak line at 106 cm{sup −1} observed in these spectra is attributed to longitudinal optical phonons in the interface layers.

  17. Magnetic anisotropies and magnetic switching in Co films

    Science.gov (United States)

    Bland, J. A. C.; Baird, M. J.; Leung, H. T.; Ives, A. J. R.; Mackay, K. D.; Hughes, H. P.

    1992-07-01

    We have used the magneto-optical Kerr effect to investigate the role of the substrate and growth conditions in determining the magnetic switching behaviour of Co films in the thickness range 100-200 Å supported by GaAs(001) and Si(111) substrates. We discuss the anisotropic magnetic hysteresis behaviour observed for Co/GaAs and Co/Si films in terms of coherent rotation of the magnetisation vector during magnetic switching. Equivalent films supported by glass substrates are found to be almost isotropic in-plane. The in-plane coercive and saturation fields are observed to lie in the range 20-80 Oe but perpendicular saturation fields of 25 and 19 kOe are found for the Co/Si and Co/GaAs systems respectively which substantially exceed the demagnetising field in each case. The measured perpendicular anisotropy fields differ strongly from the values for hcp and bcc Co and are attributed to the details of the interface and film structure. We also report strongly frequency dependent magnetic switching behaviour in these Co films.

  18. Improving the tribological and corrosive properties of MoS2-based coatings by dual-doping and multilayer construction

    Science.gov (United States)

    Shang, Kedong; Zheng, Shaoxian; Ren, Siming; Pu, Jibin; He, Dongqing; Liu, Shuan

    2018-04-01

    The pure MoS2 coating always performs high friction coefficient and short service life when used in high humidity or after long-time storage in humid atmospheric environment. In this study, the MoS2/Pb-Ti composite and MoS2/Pb-Ti multilayer coatings are deposited to improve the corrosion resistance in 3.5 wt% NaCl solution and tribological performance in high humidity condition. The electrochemical impedance spectra and salt spray test shown that the MoS2/Pb-Ti composite and multilayer coatings can inhibit the permeation of oxygen and other corrosive elements, thus resulting a high corrosion resistance. Furthermore, compared with pure MoS2 coating, the tribological performance of the MoS2/Pb-Ti composite and multilayer coatings is also improved significantly owing to the high mechanical properties and compact structure. Moreover, the heterogenous interfaces in MoS2/Pb-Ti multilayer coating play an important role to improve the corrosion resistance and tribological performance of coatings. Overall, the dual-doping and multilayer construction are promising approaches to design the MoS2 coatings as the environmentally adaptive lubricants.

  19. Structure and tribological behavior of Pb-Ti/MoS2 nanoscaled multilayer films deposited by magnetron sputtering method

    Science.gov (United States)

    Li, Hao; Xie, Mingling; Zhang, Guangan; Fan, Xiaoqiang; Li, Xia; Zhu, Minhao; Wang, Liping

    2018-03-01

    The Pb-Ti/MoS2 nanoscaled multilayer films with different bilayer period were deposited by unbalanced magnetron sputtering system. The morphology, microstructure, mechanical and tribological properties of the films were investigated. It was found that the film changed from multilayer structure to composite structure as the bilayer period decreased from 25 nm to 6 nm, due to the diffusion effect. The multilayer film showed a pronounced (002) diffraction peak, the growth of the MoS2 platelets below the interface were affected by Pb and Ti, and the c-axis of MoS2 platelets were inclined to the substrate at an angle of -30° to 30°. The hardness of the film ranged from 5.9 to 7.2 GPa depending on the bilayer period. The tribological behavior of the films was performed under vacuum, and the friction coefficient were typically below 0.25. Furthermore, the nanoscale multilayer film with a bilayer period of 20 nm exhibits much better mechanical and tribological properties than pure MoS2. The result indicates that the nanoscale multilayer is a design methodology for developing high basal plane oriented and vacuum solid lubricating MoS2 based materials.

  20. Plastic Deformation Induced by Nanoindentation Test Applied on ZrN/Si3N4 Multilayer Coatings

    Directory of Open Access Journals (Sweden)

    Zhengtao Wu

    2017-12-01

    Full Text Available ZrN/Si3N4 multilayer coating that alternates with either nanocrystalline ZrN or amorphous Si3N4 interlayers was fabricated by reactively magnetron sputtering in an Ar-N2 mixture atmosphere. The thicknesses of the nanocrystalline ZrN and the amorphous Si3N4 interlayers are ~12.5 and 2.5 nm, respectively. The ZrN/Si3N4 coating exhibits a promoted hardness of 28.6 ± 1.2 GPa when compared to the binary ZrN. Microstructure evolution just underneath the nanoindentation impression of the ZrN/Si3N4 multilayer coating has been investigated. The result indicates that both ZrN nanograin rotations and plastic flow of the Si3N4 interlayers contribute to the permanent deformation of the multilayer coating induced by the nanoindentation. In addition, the introduction of the a-Si3N4 interlayers hinders both the initiation and propagation of microcracks when the multilayer coating was applied to the scratch test. The propagation deflection of the microcracks was observed attributed to the heterogenous interface, which produces the hardness promotion of the multilayer coating eventually.