| Project/Area Number |
09640444
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
固体物性Ⅱ(磁性・金属・低温)
|
|---|
| Research Institution | Osaka City University |
|---|
Principal Investigator |
ISHII Hiroumi Faculty of Science, Osaka City University, Department of Material Science, Professor, 理学部, 教授 (80047167)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
OGURI Akira Faculty of Science, Osaka City University, Department of Material Science, Associate Professor, 理学部, 助教授 (10204166)
HATA Tohru Faculty of Science, Osaka City University, Department of Physics, Professor, 理学部, 教授 (10156333)
|
|---|
| Project Period (FY) |
1997 – 1998
|
| Project Status |
Completed (Fiscal Year 1998)
|
| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥1,000,000 (Direct Cost: ¥1,000,000)
|
|---|
| Keywords | Nuclear Magnetism / Ultralow Temperature / Negative Temperature / Singlet Ground State / Van Vleck Paramagnetism / RKKY Interaction / Dzyalosjhinsky-Moriya Interaction / Nuclear Spin Relaxation / ヴァンヴレック定磁性 / s-f交換相互作用 / 一重項基底状態 / ヴァンヴレック常磁性 / 結晶場 / 異方的超伝導 |
|---|
| Research Abstract |
In this research project we have studied following two themes.
1. Ultralow temperature property of systems consisting of conduction electrons and nuclear spins in the crystalline field singlet ground state (CFSGS).
(1) We have studied the effect of the Coulomb interaction on the superconductivity mediated by the virtual excitation of the CFSGS. The superconducting transition temperature is lowered somewhat, but the effect is not pronounced.
(2) We have derived the Coqblin-Schrieffer type s-f exchange interaction for (4f)ィイD12ィエD1 configuration with strong Hund and LS couplings. On the basis of it the RKKY interaction is derived for nuclear spins in the CFSGS system. It is of tensorial form and brings sinusoidal or helical nuclear spin structures.
(3) Nuclear magnetism of PrCu6 is studied theoretically. Experimental study by Hata, one of the investigator of this project, found an evidence for a cannted weak ferromagnet, i. e., antiferromagnetic along the b axis and ferromagnetic along the c-axis together with a hysteresis phenomenon. We payed attention to the monoclinic crystal structure in which the inversion symmetry does not hold, and then derived a Dzyaloshinsky-Moriya type RKKY interaction for nuclear spins. The theory can explain the magnetic properties found in the experiment.
2. Nuclear spin relaxation at ultralow temperatures.
(4) We have solved the anomaly found experimentally in Rh near T=0, i. e., the nuclear spin relaxation is two-times slower at negative T than at positive T. We have derived a formula for relaxation effective at ultralow temperatures and applied the high-T expansion method to it to explain the experiment.
|
