| Project/Area Number |
07454078
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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 |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | University of Tokyo |
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Principal Investigator |
TAMEGAI Tsuyoshi Univ.of Tokyo, Dept.of Applied Physics, Associate Professor, 工学系研究科, 助教授 (30183073)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBAUCHI Takasada Univ.of Tokyo, Dept.of Applied Physics, Research Associate, 工学系研究科, 助手 (00251356)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1995: ¥3,700,000 (Direct Cost: ¥3,700,000)
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| Keywords | Superclean Superconductors / Hall Effect / Vortex / Quasi-Particle / スーパークリーン / 高温超伝導体 / マイクロ波 / 微小ホール素子 |
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| Research Abstract |
In superclean superconductors, where the width of quasi-particle level is narrower than the superconducting gap, vortex dynamics is believed to be quite different compared with conventional superconductors. High temperature superconductors are one of the best candidates of this class of superconductors. The well known anomaly in the Hall effect including sign change of Hall coefficient in the mixed state can be attributed to this special feature of this class of superconductors.
With this in mind, we carried out the following three experiments related to Hall effects in high temperature superconductors ; (1)Carrier-doping dependence of the sign change of the Hall effect (2)Field dependence of low temperature critical field profile and (3)Measurement of viscosity of vortex motion.
(1)With a systematic measurements of Hall effect in a given sample by changing the carrier doping level successively, we find out that the sign change in the Hall coefficient is sustained even in the slightly overdoped region. In order to make more quantitative analysis of Hall effect, we analyzed Hall conductivity sigma_<xy'> and clarified the temperature dependence of the contributions from vortex motion and quasi-particles in the core. (2)Despite the reported huge rotation of the critical state field profile in YBa_2Cu_3O_<7-y> at low temperature, possibly due to extremely large Hall angle, we have not observed any sign of the rotation of the profile neither in YBa_2Cu_3O_<7-y> nor Bi_2Sr_2CaCu_2O_<8+y*s>. (3)For the quantitative estimation of viscosity for vortex motion, we measured field dependence of surface resistance (R_S) in Bi_2Sr_2CaCu_2O_<8+y*>. We find a characteristic field dependence of R_S**H as observed in YB_2Cu_3O_<7-y>.
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