Grant-in-Aid for Scientific Research (C).
|Research Institution||KYOTO UNIVERSITY|
MAEGAWA Satoru Kyoto University, Graduate school of human and environmental studies, Associate Professor, 大学院人間・環境学研究科, 助教授 (40135489)
|Project Fiscal Year
1994 – 1995
Completed(Fiscal Year 1995)
|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1995 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1994 : ¥1,100,000 (Direct Cost : ¥1,100,000)
|Keywords||Frustration / Triangular Lattice Antiferromagnet / Kagome Lattice Antiferromagnet / Spin Fluctuation / Successive Phase Transition / Nuclear Magnetic Resonance / Nuclear Magnetic Relaxation / Relaxation Time / フラストレーション / 三角格子反強磁性体 / かごめ格子反強磁性体 / スピン揺動 / 逐次相転移 / 核磁気共鳴 / 核磁気緩和 / 緩和時間 / 核磁気共鳴(NMR)|
The NMR spectrum and the nuclear magnetic relaxation time have been measured to investigate the phase transition, the spin structure and the fluctuation in frustrated antiferromagnets.
1. Magnetic properties in the triangular lattice Heisenberg antiferromagnet, RbNiCl_3.
(1) Successive phase transitions were confirmed and the temperature range of the intermediate phase is found to be only 0.2K.
(2) The NMR splitting of ^<87>Rb is explained by the electric quadrupole interaction including up to the second-order perturbation.
(3) A new model was proposed about the spin structure in the low temperature phase and the interactions between spins.
(4) A characteristic fluctuation in the frustrated antiferromagnets has been clarified by the measurement of the relaxation times in each phase.
2. Spin-lattice relaxation time and electron spin fluctuation in the triangular lattice Heisenberg antiferromagnet with a small easy-axis anisotropy, CsNiBr_3
(1) Spin-lattice relaxation times have been measured in the paramagnetic phase, the component disordered phase and the triangular ordered phase.
(2) It was found that the swinging fluctuation exists in the triangular ordered phase and the two-magnon process of this fluctuation contributes to the nuclear relaxation.
(3) The characteristic fluctuation in the paramagnetic phase was revealed from the relaxation time.
3. Magnetic properties and fluctuation in Kagome Lattice Antiferromagnets AFe_3(OH)_6(SO_4)_2 (A=NH_4, Na, K).
(1) Successive phase transitions were observed for the first time in the Kagome Lattice Antiferromagnets.
(2) Spin structure in each phase was considered by the measurement of the NMR spectra of^1H nad ^<23> Na.
(3) The characteristic fluctuation in Kagome Lattice Antiferromagnet was found.