1988 Fiscal Year Final Research Report Summary
NMR Studies of Structural Phase Transitions of Quasi one-dimensional Jahn-Teller Crystals
| Project/Area Number |
62540246
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
HAUO NIKI Division of General Education, Assistant Professor, 教養部, 講師 (80145549)
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| Co-Investigator(Kenkyū-buntansha) |
KATSUMA YAGASAKI College of Science, Associate Professor, 理学部, 助教授 (70045037)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Nuclear Magnetic Resonance (NMR) / Nuclear Quadrupole Resonance (NQR) / Low Dimensional Magnetic Materials / Structural Phase Transition / ヤーンーテラー効果 |
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| Research Abstract |
The ABX_3 type of Jahn-Teller crystal such as CsCuCl_3 and RbCuCl_3 undergo structural phase transition which has been studied microscopically by NMR and NQR. Since the change of physical properties induced by the phase transition is revealed by the frequency, line width and relaxation time of resonance, accurate measurement of these quantities is necessary. Since the Cu atom is par-amagnetic in room temperatures, line width and relaxation time of resonance signal of each atom are broader than those of non-magnetic substances by the order of 10. Moreover, since measurement at high temperatures are required, it was urgent to improve S/N ratio, necessarily resulting in construction and improvement of NMR and NQR apparatus. Following are two features in constructing and improving the apparatus 1) Development of a marginal oscillator capable of wide-line and automatic measurement. 2) Construction of apparatus for NMR and NQR for pulse method. These apparatus were employed in NMR measurements of ^1H nucleus of high temperature superconductor YBa_2Cu_3O_7- H_<0.2>. The magnetic field penetration depth can be de-termined from the temperature dependence of NMR line width and the knowledge of spin-lattice relaxation time T_1 has been acquired. Moreover, use of the apparatus for Cl NQR in Chloral Iso-Butylhemiacetal has given much knowledge about lattice defect. The study of Jahn-Teller crystals CsCuCl_3 and RbCuCl_3 and clarification of the origin of their structural phase transitions will be extensively continued.
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