| Project/Area Number |
14540342
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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 |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | OSAKA CITY UNIVERSITY |
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Principal Investigator |
YANO Hideo Osaka City University, Graduate School of Science, Lecturer, 大学院・理学研究科, 講師 (70231652)
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| Co-Investigator(Kenkyū-buntansha) |
HATA Tohru Osaka City University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (10156333)
OBARA Ken Osaka City University, Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (50347481)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2003: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2002: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | superfluid helium 3 / impurity effect / aerogel / proximity effect / NMR / nuclear demag. cryostat / ultralow temperature / 超流動^3He |
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| Research Abstract |
We have investigated the proximity effect at the boundary of super and normal fluid ^3He using an aerogel. The porosity of the aerogel was 97.5 %, which corresponds to 2.5 % impurity. We injected the aerogel into a half of a cell and formed a boundary at the center. We prepared magnetic or non-magnetic impurities by adsorbing ^3He or ^4He gas, respectively, on the silica strands of the aerogel. We measured the nuclear spin structures by the NMR method.
The superfluid transition temperature of ^3He in the 2.5 % impurities is lower than those in lower impurities. We found two types of the superfluid phases at pressures above 2.1 MPa and clarified those by the pulsed NMR method : the phase at higher temperatures is the ABM-like (A-like) and the other the BW-like (B-like). Those phenomena are quite different from ^3He in narrow spaces, and the strands of the aerogels are considered impurities for ^3He.
The superfluid transitions were observed at higher temperatures in non-magnetic impurities than in magnetic impurities. Those results indicate that the p-wave of Cooper pairs are easily destroyed by the magnetic impurities. We observed a coexistence state of the A-like and the B-like phase of ^3He only in the non-magnetic impurities. We also observed the coexistence state at the boundary and found that its ratio at the boundary is as same as in the impurities. This result suggests that the proximity effect does not affect the coexistence state. On the other hand we observed a peculiar spin structure at the boundary between the superfluid state in the bulk and the normal state in the impurities. Those should be caused by the proximity effect at the boundary.
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