| Project/Area Number |
11450239
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Shimane University |
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Principal Investigator |
YAMADA Yuh Interdisciplinary Faculty of Science and Engineering, Shimane University, Associate Prof., 総合理工学部, 助教授 (10242835)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUSHITA Akiyuki National Institute for Materials Science, Materials Engineering Laboratory, Materials Physics Research Group, Senior Researcher, 材料研究所・基礎物性グループ, 主席研究員
KUBO Shugo Interdisciplinary Faculty of Science and Engineering, Shimane University, Prof., 総合理工学部, 教授 (30294359)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥11,900,000 (Direct Cost: ¥11,900,000)
Fiscal Year 2001: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2000: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1999: ¥6,400,000 (Direct Cost: ¥6,400,000)
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| Keywords | The strongly correlated electron oxide / The effects of pressure / High T_2 oxide superconductor / The Rietveld refinement / The structural analysis / 強相関酸化物 / 高圧X線回折 / マキシマムエントロピー法 |
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| Research Abstract |
We have investigated the electric and crystal structural changes on the strongly correlated electron oxide and alloys under high pressure. The results are explained in the following.
(1) We have successfully grown single crystals of PrBa_2Cu_4O_8 (Pr124) by a flux method under high-pressure oxygen gas. The structure data of a Pr124 single crystal were taken by using a four-circle diffractometer and the structure was refined by full matrix least-square structure refinements. All z-positional parameters are essentially the same between the single crystal and the polycrystalline Pr124. The temperature dependence of resistivity of Pr124 single crystals did not exhibit superconductivity, at least down to 2 K. Resistivity along the b- axis showed a highly conductive behavior, of which the origin is attributed to the double-chain site because of the large anisotropy between the resistivities along a- and b- axes.
(2) The RuSr_2GdCu_2O_8 oxide exhibits the superconducting transition at about 40K and ferromagnetic order at about 130K. The pressure dependence of the superconducting and ferromagnetic transition temperature of this sample was measured. The superconducting transition temperature was scarcely varies under pressure. The ferromagnetic transition temperature increases with increasing pressure.
(3) Magnetization, electrical resistivity and specific heat measurements have been made on Heusler-type Fe_2VAl compound. The electrical resistivity shows semiconductor-like negative temperature dependence. We suggested that this compound should be a semimetal with a pseudogap in the density of states at the Fermi level.
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