2001 Fiscal Year Final Research Report Summary
Strongly Correlated Electron Systems in Multiple Extreme Conditions
| Project/Area Number |
11440110
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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 | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SUZUKI Takashi Hiroshima University, Graduate School of Advanced Science of Matter, Associate Professor, 大学院・先端物質科学研究科, 助教授 (00192617)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Masakazu Hiroshima University, Graduate School of Advanced Science of Matter, Research Associate, 大学院・先端物質科学研究科, 助手 (40294524)
NAKAMURA Fumihiko Hiroshima University, Graduate School of Advanced Science of Matter, Research Associate, 大学院・先端物質科学研究科, 助手 (40231477)
FUJITA Toshizo Hiroshima University, Graduate School of Advanced Science of Matter, Professor, 大学院・先端物質科学研究科, 教授 (20004369)
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| Project Period (FY) |
1999 – 2001
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| Keywords | extreme conditions / specific heat / electric resistivity / pressure effects / quadrupolar order / phase diagram / elastic moduli |
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| Research Abstract |
1. Magnetic field dependence of the ferroquadrupolar ordering temperature in UCu_2Sn
We found that UCu_2Sn undergoes a ferroquadrupolar transition and explained the origin for the transition, which occurs due to the quadrupolar instability of the non-magnetic ground state doublet Г5. In the research in 2001, we measured many thermodynamic properties in magnetic field along various directions to determine the field dependence of the transition temperature, and established the phase diagram. From the analysis by taking account of the strain-multipolar interaction, Zeeman interaction, we succeeded in establishing the CEF model which explain all properties we measured.
2. Magnetic field induced irreversibility in UNiAl
We measured magnetization, magnetoresistivity, Hall coefficient, magnetostriction and elastic moduli of UNiAl under magnetic fields up to 14T. We found that this compound at 7 K shows the first order meta-magnetic transition from an antiferromagnetic to ferromagnetic phase at 11.35T with increasing field. Especially, it is interesting that the meta-magnetic transition shows a remarkable history effect. We explained the history effect due to the irreversible change in the magnetic structural propagation vector in the basal plane of the hexagonal structure from the neutron scattering experiments.
3. Strain dependence of the superconducting transition temperature in Sr_2Ruo_4
Using a high-quality single crystal of this compound, we measured precisely temperature dependence of various elastic moduli. We found a clear jump-like decrease in the longitudinal C11 at the superconducting transition temperature. Using the Ehrenfest relation, we determined the strain and uniaxial pressure dependence of Tc. We also found a jump-like behavior at Tc in transverse modes, which suggests a asymmetric time-reversal 2-dimensional superconducting order parameter.
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