The Experts below are selected from a list of 24924 Experts worldwide ranked by ideXlab platform
Migaku Takahashi - One of the best experts on this subject based on the ideXlab platform.
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extra large unidirectional Anisotropy Constant of co fe mn ir bilayers with ultra thin antiferromagnetic layer
Journal of Magnetism and Magnetic Materials, 2002Co-Authors: Masakiyo Tsunoda, Kazuhiro Nishikawa, Thorsten Damm, Takahiko Hashimoto, Migaku TakahashiAbstract:Abstract Unidirectional Anisotropy Constant, JK, of Co1−xFex/Mn–Ir bilayer was investigated as a function of the Fe concentration, x. As a result, we obtained an extra large value of JK, which exceeds 0.5 erg/cm2, at x=0.3–0.4 with the ultra-thin (50–100 A) Mn–Ir layer. The blocking temperature of Co0.7Fe0.3 40 A/Mn–Ir 100 A bilayer was 290°C, which is sufficiently high for the application of spin valve giant magnetoresistive devices.
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single spin ensemble model for the change of unidirectional Anisotropy Constant by annealing on polycrystalline ferromagnetic antiferromagnetic bilayers
Journal of Applied Physics, 2000Co-Authors: Masakiyo Tsunoda, Migaku TakahashiAbstract:A model for the exchange coupled polycrystalline ferromagnetic/antiferromagnetic (F/AF) bilayers is proposed in order to discuss the mechanism of the change of the unidirectional Anisotropy Constant (JK) of the bilayers by thermal annealing. The AF layer is treated as an aggregation of the AF grains whose magnetic Anisotropy axes lay in the film plane with two-dimensionally random distribution. Two stable states concerning the direction of the AF spins are calculated for the AF grain. Determining the populations of the AF grains in each state in thermal equilibrium, total energy of the system is obtained, which provides the magnetization curves and the magnetic torque curves of the F/AF bilayers. The calculated results show the reduction of JK with increasing the equilibrium temperature, which is due to the changes of the probability functions for the respective spin alignments of the AF grain. We conclude that the changes in JK do not necessarily need any changes of the microstructure and the intrinsic p...
Masakiyo Tsunoda - One of the best experts on this subject based on the ideXlab platform.
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extra large unidirectional Anisotropy Constant of co fe mn ir bilayers with ultra thin antiferromagnetic layer
Journal of Magnetism and Magnetic Materials, 2002Co-Authors: Masakiyo Tsunoda, Kazuhiro Nishikawa, Thorsten Damm, Takahiko Hashimoto, Migaku TakahashiAbstract:Abstract Unidirectional Anisotropy Constant, JK, of Co1−xFex/Mn–Ir bilayer was investigated as a function of the Fe concentration, x. As a result, we obtained an extra large value of JK, which exceeds 0.5 erg/cm2, at x=0.3–0.4 with the ultra-thin (50–100 A) Mn–Ir layer. The blocking temperature of Co0.7Fe0.3 40 A/Mn–Ir 100 A bilayer was 290°C, which is sufficiently high for the application of spin valve giant magnetoresistive devices.
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single spin ensemble model for the change of unidirectional Anisotropy Constant by annealing on polycrystalline ferromagnetic antiferromagnetic bilayers
Journal of Applied Physics, 2000Co-Authors: Masakiyo Tsunoda, Migaku TakahashiAbstract:A model for the exchange coupled polycrystalline ferromagnetic/antiferromagnetic (F/AF) bilayers is proposed in order to discuss the mechanism of the change of the unidirectional Anisotropy Constant (JK) of the bilayers by thermal annealing. The AF layer is treated as an aggregation of the AF grains whose magnetic Anisotropy axes lay in the film plane with two-dimensionally random distribution. Two stable states concerning the direction of the AF spins are calculated for the AF grain. Determining the populations of the AF grains in each state in thermal equilibrium, total energy of the system is obtained, which provides the magnetization curves and the magnetic torque curves of the F/AF bilayers. The calculated results show the reduction of JK with increasing the equilibrium temperature, which is due to the changes of the probability functions for the respective spin alignments of the AF grain. We conclude that the changes in JK do not necessarily need any changes of the microstructure and the intrinsic p...
A Del Moral - One of the best experts on this subject based on the ideXlab platform.
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measuring the magnetoelastic Anisotropy Constant in manganite epitaxial thin films
Journal of Magnetism and Magnetic Materials, 2004Co-Authors: J I Arnaudas, A Del Moral, M Ciria, L Benito, C De La Fuente, M R Ibarra, M Bibes, Ll Balcells, J FontcubertaAbstract:Abstract We present direct measurement and indirect determination of the irreducible magnetoelastic stress coefficient B1 performed in La2/3Ca1/3MnO3 epitaxial thin films grown on SrTiO3(0 0 1) and LaAlO3(0 0 1) substrates. The values obtained are, respectively, −13 and −16 MPa. These results suggest the magnetoelastic origin of the magnetic Anisotropy energy that induces out-of-plane magnetization in La2/3Ca1/3MnO3/LaAlO3 (0 0 1) thin films.
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macroscopic random magnetic Anisotropy Constant in crystalline dyxy1 xal2 x 0 3 0 4
Journal of Applied Physics, 1994Co-Authors: A Del Moral, M Ciria, J I Arnaudas, J S AbellAbstract:Cooling in a weak magnetic field the random magnetic Anisotropy (RMA) spin glasses DyxY1−xAl2 (x=0.3, 0.4) induces unidirectional and uniaxial anisotropies, on top of the cubic coherent one. The unidirectional Anisotropy Constant KRMAu has been determined at 3.8 K, amounting at zero applied field 127 and 255 J/m3 for x=0.3 and 0.4, respectively. The predicted model ratio between KRMAu and the uniaxial Constant KRMAa, i.e., KRMAa=2KRMAu, has been confirmed. As by‐product the relevant RMA parameter D2/J, where D is the RMA crystal field strength and J, the exchange Constant has been determined, as well as separate estimates of D and J.
J I Arnaudas - One of the best experts on this subject based on the ideXlab platform.
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measuring the magnetoelastic Anisotropy Constant in manganite epitaxial thin films
Journal of Magnetism and Magnetic Materials, 2004Co-Authors: J I Arnaudas, A Del Moral, M Ciria, L Benito, C De La Fuente, M R Ibarra, M Bibes, Ll Balcells, J FontcubertaAbstract:Abstract We present direct measurement and indirect determination of the irreducible magnetoelastic stress coefficient B1 performed in La2/3Ca1/3MnO3 epitaxial thin films grown on SrTiO3(0 0 1) and LaAlO3(0 0 1) substrates. The values obtained are, respectively, −13 and −16 MPa. These results suggest the magnetoelastic origin of the magnetic Anisotropy energy that induces out-of-plane magnetization in La2/3Ca1/3MnO3/LaAlO3 (0 0 1) thin films.
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macroscopic random magnetic Anisotropy Constant in crystalline dyxy1 xal2 x 0 3 0 4
Journal of Applied Physics, 1994Co-Authors: A Del Moral, M Ciria, J I Arnaudas, J S AbellAbstract:Cooling in a weak magnetic field the random magnetic Anisotropy (RMA) spin glasses DyxY1−xAl2 (x=0.3, 0.4) induces unidirectional and uniaxial anisotropies, on top of the cubic coherent one. The unidirectional Anisotropy Constant KRMAu has been determined at 3.8 K, amounting at zero applied field 127 and 255 J/m3 for x=0.3 and 0.4, respectively. The predicted model ratio between KRMAu and the uniaxial Constant KRMAa, i.e., KRMAa=2KRMAu, has been confirmed. As by‐product the relevant RMA parameter D2/J, where D is the RMA crystal field strength and J, the exchange Constant has been determined, as well as separate estimates of D and J.
Christophe Payen - One of the best experts on this subject based on the ideXlab platform.
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Comparative study of core-shell iron/iron oxide gold covered magnetic nanoparticles obtained in different conditions
Journal of Nanoparticle Research, 2011Co-Authors: C. Leostean, O. Pana, R. Turcu, M. L. Soran, S. Macavei, Olivier Chauvet, Christophe PayenAbstract:In this study, we report the synthesis and characterization of the core-shell Fe covered with Au shells nanoparticles with mean diameters between 5 and 8 nm. The inverse micelles method was utilized to produce the samples. X-ray diffraction studies show that both core-shell systems have the expected crystalline structure. High resolution transmission electron microscopy and atomic emission spectroscopy techniques give additional information concerning the structure and composition of nanoparticles. An intermediate shell of amorphous oxidized iron was found between the magnetic Fe core and the external gold shell. The magnetic behavior of different core-shell samples shows no hysteresis loop indicating the superparamagnetic behavior of Fe@Au systems. The superparamagnetic behavior is also evidenced from FC and ZFC dependences of the magnetization versus temperature. By using the temperature dependence of the thermoremanent magnetization combined with magnetization versus applied magnetic field, the effective Anisotropy Constant was determined. The Fe/Au interface contribution to the effective Anisotropy Constant was calculated and discussed in relation with the combined shape and stress anisotropies.
