2001 Fiscal Year Final Research Report Summary
NMR Study of Pressure-induced Superconductivity and Pressure-induced Weak Magnetism in f-electron Systems
| Project/Area Number |
12640358
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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 | Himeji Institution of Technology |
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Principal Investigator |
KOHARA Takao Faculty of Sci. Himeji Institute of Technology, Professor, 理学部, 教授 (70107986)
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| Co-Investigator(Kenkyū-buntansha) |
IWAMOTO Yuji Faculty of Sci.Himeji Institute of Technology, Assist., 理学部, 助手 (80244680)
UEDA Koh-ichi Faculty of Sci.Himeji Institute of Technology, Assist., 理学部, 助手 (20203440)
KOHORI Yoh Faculty of Sci.Assoc.Himeji Institute of Technology, Professor, 理学部, 助教授 (10153660)
MATSUDA Kazuyuki Faculty of Sci.JSPS Res. Himeji Institute of Technology, Fellowships for Young Sci., 理学部, 学振・特別研究員
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| Project Period (FY) |
2000 – 2001
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| Keywords | Pressure-induced Superconductors / Nuclear Magnetic Resonance / Nuclear Quadrupole Resonance / d-wave Superconductivity / Spin Fluctuation / f-electron Compounds / Heavy Electron Systems / Low Temperature Material Sciences under High Pressure |
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| Research Abstract |
The main purpose of this subject is for exploring the mechanisms of unconventional superconductivity and a tiny magnetic moment induced by applied high pressure in f-electron compounds. This project consists of two-sample groups; (1) pressure induced superconductors of CeTIn_5 (T= Rh, Co, Ir) and CeRh_2Si_2 and (2) Uru_2Si_2 with tiny magnetic moments. Present ^<115>NQR measurements in the super conducting state were performed on CeCoIn_5, Celrln_5 and CeRhln_5 under high pressure above the critical pressure of 1.7GPa. As for CeTIn_5 in the super conducting state, the nuclear magnetic relaxation rate has T^3 -dependence and the spin susceptibility decreases upon cooling. These results indicate that these systems exhibit d-wave superconductivity. On the other hand, CeCoIn_5 in the normal state is located just at antiferromagnetic instability and CeRhln_5 above the critical pressure and Celrln_5 are in the nearly antiferromagnetic region. Next, we have found new ^<29>Si NMR signals coming from the antiferromagnetic region in Uru_2Si_2 together with previously reported Si NMR signals from the paramagnetic region. These signal-intensities compete with each other depending on temperature and applied pressure. This result gives evidence for spatially inhomogeneous development of antiferromagnetic ordering below characteristic temperature. The ordered magnetic moments of U are expected as about 0.4 μ, B, which is of about one order of magnitude larger than 0.03 μ B measured by many neutron diffraction experiments. This picture of inhomogeneous development of antiferromagnetic region will bring us to the new scenario of understanding of hidden order parameters, which is still unsolved since the discovery of this interesting material in '85.
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