2001 Fiscal Year Final Research Report Summary
ESR and Cyclotron Resonance of Strongly Correlated Materials
| Project/Area Number |
08404022
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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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 | Tohoku University |
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Principal Investigator |
MOTOKAWA Mitsuhiro Institute for Materials Research, Tohoku University, Professor, 金属材料研究所, 教授 (30028188)
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| Co-Investigator(Kenkyū-buntansha) |
OHTA Hitoshi Faculty of Science, Kobe University, Associate Professor, 理学部, 助教授 (70194173)
KOYAMA Kei-ichi Institute for Materials Research, Tohoku University, Research Associate, 金属材料研究所, 助手 (70302205)
TAKUO Sakon Institute for Materials Research, Tohoku University, Research Associate, 金属材料研究所, 助手 (80271964)
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| Project Period (FY) |
1996 – 1999
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| Keywords | heavy-electron systems / cyclotron resonance / magnetic resonance / CoS_2 / low-carrier systems / GdAs |
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| Research Abstract |
Continuing the experiments done last year, we have performed the magnetic resonance and cyclotron resonance on some rare-earth compounds using vector network analyzer system developed recently at ultra low temperatures and high magnetic fields. A microwave cavity has been used for high sensitivity. The frequency range is 40〜110 GHz and the temperature range is 0.5〜300 K. The obtained results are as follows :
1) GdAs : The magnetic structure of this compound with easy (111) plane, which had been unknown so far, has been determined by ESR. The cyclotron resonance has been observed at 0.5 K and the effective mass of the carrier is detemined as 0.48 m0. This result suggests that the fermi surface is spherical and the effective mass is two times larger than that obtained by quantum oscillation.
2) LaSb : The cyclotron resonance has been observed below 4.2 K. From the anisotropic behavior of the resonance position, this resonance occurs due to carriers with a ellipsoidal fermi surface. The effective mass obtained is 0.26 m0 along the <100> direction and is two times larger than that obtained by quantum oscillation.
The difference between masses obtained by cyclotron resonance and quantum oscillaation has been observed for low dimensional organic conductors. However the former is larger than the latter and consistent with the theoretical prediction, which is against our result. In this study, we have first observed the cyclotron resonance on strongly correlated materials, which has never reported, and determined the effective mass directly. The theory to explain our result has not been done yet.
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