| Project/Area Number |
13650347
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Yamaguchi University |
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Principal Investigator |
ASADA Hironori Yamaguchi University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (70201887)
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| Co-Investigator(Kenkyū-buntansha) |
KOYANAGI Tsuyoshi Yamaguchi University, Faculty of Engineering, Professor, 工学部, 教授 (90178385)
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2002: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2001: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | diluted magnetic semiconductor / carrier induced ferromagnetism / IV-VI semiconductor / GeTe / ferromagnetic semiconductor / spin / IV-VI族 / スピン半導体 / キャリア誘起 / 強磁性体 |
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| Research Abstract |
We have studied (1) the preparation of new diluted magnetic semiconductors (DMSs), (2) fabrication of ferromagnetic fine structure using phase change technique, and (3) magnetic property control and spin transport phenomena, for IV-VI compound GeTe based DMSs and its multi-structures, and obtained the following results
(1) GeTe based DMSs having the similar composition (x〜0.15) of 3d transition metals (from Ti to Ni) have been prepared by a rf sputtering. Ferromagnetic order was newly observed for Cr and Fe doped films in addition to Ge_<1-x>Mn_xTe. The higher Curie temperature 100 K was obtained for Fe doped film with the lower carrier concentration than the other ferromagnetic GeTe based DMSs
(2) The crystalline wire with 1.0 μ m width has been successfully formed in a paramagnetic amorphous Ge_<1-x>Mn_xTe film by irradiating a focused laser beam through the objective lens (beam spot size=l.2 μ m^2). After the irradiation, the ferromagnetic phase of crystalline wires was confirmed by b
… More
oth the M-H curves and magnetotransport measurements
(3) In order to control the coercive field of upper Ge_<1-x>Mn_xTe layer, Ge_<1-x>Mn_xTe/GeTe/Ge_<1-x>Mn_xTe/MnTe multilayers were fabricated. The intermediate shoulder was observed in the M-H hysteresis, which suggested the selective switching in the two Ge_<1-x>Mn_xTe layers. The magnetoresistance ratio in multilayer is 4.9 %, which is one order larger than that in single layer (0.37 %). Ge_<1-x>Mn_xTe films having the same Mn composition but different carrier concentrations ranging from 10^<19> to 10^<21> cm^<-3> have been successfully prepared. The spontaneous magnetization increased and the coercive field decreased with increasing carrier concentration. This suggested the possibility of selective magnetization switching by controlling the carrier concentration. The magnetic phase transition has been investigated using magnetotansport measurements. The values of the critical exponents were close to those for the Heisenberg model than for the mean field model Less
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