| Project/Area Number |
04452036
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAKEUCHI Shin The University of Tokyo, Inst.Solid State Physics, Professor, 物性研究所, 教授 (60013512)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Kunio The University of Tokyo, Inst.Solid State Physics, Research Associate, 物性研究所, 助手 (50107439)
EDAGAWA Keiichi The University of Tokyo, Inst.Solid State Physics, Research Associate, 物性研究所, 助手 (20223654)
KIMURA Kaoru The University of Tokyo, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30169924)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1993: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1992: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Quasicrystal / Crystal approximant / Electrical conductivity / Electron localization / Hopping conduction |
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| Research Abstract |
1. Main results obtained for high quality samples are as follows :
(1) In A1-Pd-Mn icosahedral phase, electrical resistivity increases almost linearly with deceasing temperature and shows a maximum at few tens of Kelvin and then decreases in low Mn-concentration alloys. The specific resistivity at helium temperature is generally quite high and varies from 10^3 to 10^4 mu OMEGA cm depending on the alloy composition. The temperature dependence of the resistivity, as well as the magnetoresistance effect, can be interpreted by the weak-localization theory that takes into account the spin-orbit interaction.
(2) Also in Al-Pd-Re icosahedral phase, the resistivity is extremely high and varies sensitively with the composition. In some Al_<70>Pd_<20>Re_<10> alloys, the resistivity value reaches as high as 1O MEGA cm at helium temperature, which is the highest value ever reported for quasicrystals. Temperature and magnetic field dependences of the resistivity are interpreted by the weak-localization theory except the samples with the highest resistivity which show hoping-like conduction.
(3) In Al-Cu-Ru and Al-Cu-Fe icosahedral phases, the electrical conductivity varies as T^<1/2> below a few tens of Kelvin due to the electron-electron interaction effect and as T linear above the temperature due to the weak-localization effect. Hall coefficient measurements have suggested the temperature variation of the carrier density.
2. From the experimental results so far obtained, we get the following picture : in both high-quality quasicrystals and their high-order crystal approximants, a deep pseudo-gap is always forms at the Fermi-level due to the Fermi-surface quasi-Brillouin zone boundary interaction, and the electrons near the Fermi-level have a stronger tendency to localize as the pseudo-gap deepens ; these circumstances produce characteristic behavior of electrical resistivity in quasicrystals.
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