Faculty Profiles - TANIYAMA Tomoyasu

Papers - TANIYAMA Tomoyasu

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Control of magnetic anisotropy and magnetotransport in epitaxial micropatterned (Ga,Mn)As wire structures Reviewed International journal

K Hamaya, R Moriya, A Oiwa, T Taniyama, Y Kitamoto, H Munekata

IEEE TRANSACTIONS ON MAGNETICS Vol. 39 ( 5 ) page： 2785 - 2787 2003.9

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The authors present magnetoresistance characteristics of patterned (Ga,Mn)As wire structures, which depend on wire width and thus overall magnetic anisotropy. Cubic and uniaxial magnetocrystalline anisotropies seem to be the, dominant magnetic contributions in 2-mum-wide wires, whereas both magnetocrystalline and shape-induced anisotropies, contribute to magnetization reversal in 1mum-wide wires, as manifested by jumps in the magnetoresistance curves. The role of these two anisotropies in the magnetization reversal is discussed, together with the determination of magnetic easy/hard axes of (Ga,Mn)As wires.

DOI： 10.1109/TMAG.2003.815710

Web of Science

Scopus

J-GLOBAL

Anomalous hall resistivity due to grain boundary in manganite thin films Reviewed International journal

T. Taniyama, K. Hamaya, Y. Kitamoto, Y. Yamazaki

Journal of Applied Physics Vol. 93 ( 10 ) page： 8107 - 8109 2003.5

Language：English Publishing type：Research paper (international conference proceedings)

The anomalous Hall resistivities of polycrystalline manganite thin films with different grain sizes were analyzed. Positive anomalous Hall coefficients due to grain boundaries were observed in addition to a negative contribution in the bulk manganite. The temperature dependence of the anomalous Hall resistivity was found to be in agreement with its magnetoresistive feature.

DOI： 10.1063/1.1543865

Cation order and magnetic properties of double perovskite Sr2FeMoO6 Reviewed International journal

H Sakuma, T Taniyama, Y Kitamoto, Y Yamazaki

JOURNAL OF APPLIED PHYSICS Vol. 93 ( 5 ) page： 2816 - 2819 2003.3

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

A double perovskite. type compound Sr2FeMoO6 was synthesized by a solid-state reaction. The order parameter (x) of Fe and Pt ions on the B sites increased from 68% to 82% and the spontaneous magnetization at 5 K increased from 2.1 to 3.0 mu(B) per formula unit by lowering the calcination temperature from 1100 to 500degreesC. The dependence of the spontaneous magnetization on x was discussed using two models considering the local magnetic interactions between ions on the B sites. Fe-57 Mossbauer analysis suggested the existence of tiny areas of SrFeO3-delta in Sr2FeMoO6. (C) 2003 American Institute of Physics.

DOI： 10.1063/1.1544088

Web of Science

J-GLOBAL

Asymmetric transport due to spin injection into a Kondo alloy Reviewed International journal

T Taniyama, N Fujiwara, Y Kitamoto, Y Yamazaki

PHYSICAL REVIEW LETTERS Vol. 90 ( 1 ) page： 016601/1 - 4 2003.1

Language：English Publishing type：Research paper (scientific journal) Publisher：AMERICAN PHYSICAL SOC

Spin injection is found to have a significant effect on the transport properties of the Kondo alloy Cu(Fe). When a spin-polarized electron current flows from Co into Cu(Fe) wires through the Co/Cu(Fe) interface, the resistivity of the Cu(Fe) wire is suppressed near the interface, as distinct from the ordinary logarithmic increase in the resistivity at low temperatures. For the opposite current direction, no significant changes are observed. The asymmetry of the resistivity with respect to the current direction decays with a characteristic length of 1.5+/-0.4 mum at 2.5 K as the distance from the interface is increased. Possible mechanisms for the asymmetry are discussed.

DOI： 10.1103/PhysRevLett.90.016601

Web of Science

Optical studies of spin injection and detection at ferromagnet/semiconductor interfaces International journal

J.A.C. Bland, S.J. Steinmuller, A. Hirohata, W.S. Cho, Y.B. Xu, C.M. Guertler, G. Wastlbauer, A. Inonescu, T. Taniyama, T. Trypiniotis

Europhys. News Vol. 34 ( 6 ) page： 240 2003

FePt nanoparticle-assembly for magnetic recording media Reviewed

Kitamoto Y, Sakuma H, Jogo A, Taniyama T, Yamazaki Y, Nishio H, Yamamoto H

MAGNETIC MATERIALS, PROCESSES, AND DEVICES VII AND ELECTRODEPOSITION OF ALLOYS, PROCEEDINGS Vol. 2002 ( 27 ) page： 483-490 2003

Crossover of magnetotransport process toward spin-polarized tunneling in manganite thin films Reviewed International journal

T Taniyama, M Yamasaki, Y Yamazaki

APPLIED PHYSICS LETTERS Vol. 81 ( 24 ) page： 4562 - 4564 2002.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

We report on the magnetoresistive features of well-characterized polycrystalline manganite thin films as a function of film thickness. A crossover of the magnetization process from domain wall displacement to magnetic rotation of each grain is observed around a thickness of 25 nm, accompanied with the maximum of the coercivity. The thickness dependence of the electrical resistivity clearly distinguishes the transport mechanism at 25 nm, below which the magnetoresistance can be well scaled by similar to(M/M-S)(2), using the magnetization M and the saturation magnetization M-S. Spin-polarized tunneling transport between adjacent grains provides a comprehensive picture for the magnetotransport data. (C) 2002 American Institute of Physics.

DOI： 10.1063/1.1528282

Web of Science

CiNii Research

J-GLOBAL

Surface magnetism of Pd-Fe fine particles Reviewed International journal

T Shinohara, M Shigemune, T Sato, T Taniyama

IEEE TRANSACTIONS ON MAGNETICS Vol. 38 ( 5 ) page： 2634 - 2636 2002.9

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Magnetization and ac susceptibility measurements of Pd98.0Fe2.0 fine particles (average radii of 7.6-20.4 nm) gave the evidence of magnetic ordering of the surface layer in fine particle. The magnetic transition temperature of the surface layer in Pd-Fe fine particles was determined to be about 40 K based on the peaks in nonlinear susceptibility, and it slightly decreased with decreasing the particles size. Moreover, the size dependence of saturation magnetization indicates that the surface layer has no saturation magnetization at low temperature.

DOI： 10.1109/TMAG.2002.801968

Web of Science

J-GLOBAL

Change in resistance of CuFe wires induced by spin injection Reviewed International journal

T. Taniyama, N. Fujiwara, Y. Kitamoto, Y. Yamazaki

IEEE Transactions on Magnetics Vol. 38 ( 5 I ) page： 2872 - 2874 2002.9

Language：English Publishing type：Research paper (international conference proceedings)

Spin injection from a ferromagnetic metal Co into a Kondo alloy CuFe is demonstrated using the devices with a Co/CuFe wire junction. The temperature dependent resistivity of CuFe shows an increase below 20 K as spin current flows from CuFe into Co as seen in Kondo alloys. In contrast, the resistivity for the opposite current direction from Co into CnFe decreases at low temperatures at a current of 250 μA. The difference between the resistivities of both the current directions logarithmically increases with decreasing temperature, indicating the suppression of the spin scattering at Fe impurities that causes the logarithmic increase in Kondo alloys.

DOI： 10.1109/TMAG.2002.803135

Web of Science

Scopus

J-GLOBAL

Magneto-optical properties and morphology of particulate film consisting of Bi-YIG coprecipitated particles Reviewed

Kuroda CS, Taniyama T, Kitamoto Y, Yamazaki Y

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 241 ( 2-3 ) page： 201-206 2002.3

Strain-induced anisotropic low-field magnetoresistance of La-Sr-Mn-O thin films Reviewed

Choi KK, Taniyama T, Yamazaki Y

JOURNAL OF APPLIED PHYSICS Vol. 90 ( 12 ) page： 6145-6150 2001.12

Selective dry etching of manganite thin films for high sensitive magnetoresistive sensors Reviewed

Naoe M, Hamaya K, Fujiwara N, Taniyama T, Kitamoto Y, Yamazaki Y

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 235 ( 1-3 ) page： 223-226 2001.10

Improvement in magneto-optical properties of Bi-YIG particulate films by reduction in particle size Reviewed

Kuroda CS, Taniyama T, Kitamoto Y, Yamazaki Y, Hirano T

IEEE TRANSACTIONS ON MAGNETICS Vol. 37 ( 4 ) page： 2432-2434 2001.7

Magnetotransport and Mossbauer study of Fe3O4/gamma Fe2O3 granular thin films Reviewed

Taniyama T, Kitamoto Y, Yamazaki Y

JOURNAL OF APPLIED PHYSICS Vol. 89 ( 11 ) page： 7693-7695 2001.6

Magnetoresistance of manganite thin films induced by reaction with substrate Reviewed Open Access

Hamaya K, Taniyama T, Yamazaki Y

JOURNAL OF APPLIED PHYSICS Vol. 89 ( 11 ) page： 6320-6323 2001.6

X-ray magnetic circular dichroism of PdFe fine particles at Pd L-2,L-3 edges Reviewed

Shinohara T, Sato T, Taniyama T, Sakurai H

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 226 page： 1939-1941 2001.5

Magnetotransport and spin con-figurations in patterned ferromagnetic wires Reviewed

Taniyama T, Nakatani L, Yakabe T, Nomura A, Shiiki K, Yamazaki Y

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 226 page： 1850-1852 2001.5

Iron mixed-valence compounds, BaSm(Cu0.5+xFe0.5-x)(2)O5+delta II: The Fe2.5+ state and magnetic properties Reviewed

Linden J, Nakamura J, Pietari T, Taniyama T, Karppinen M, Yamauchi H

PHYSICA C Vol. 338 ( 1-2 ) page： 126-131 2000.8

Magnetic properties, oxygen content and metal valences in BaRE(Cu0.5Fe0.5)(2)O5+delta with RE = Lu, Yb, Y, Eu, Sm, Nd and Pr Reviewed

Kochi M, Linden J, Taniyama T, Lehmus K, Karppinen M, Yamauchi H

PHYSICA C Vol. 338 ( 1-2 ) page： 132-136 2000.8

Magnetic and magneto-transport properties of gamma Fe2O3-grain-embedded Fe3O4 thin films Reviewed

Uotani M, Taniyama T, Yamazaki Y

JOURNAL OF APPLIED PHYSICS Vol. 87 ( 9 ) page： 5585-5587 2000.5

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Papers - TANIYAMA Tomoyasu