Spin fluctuation in frustrated antiferromagnets

受挫反铁磁体中的自旋涨落

• 批准号: 06640474
• 负责人: MAEGAWA Satoru
• 金额: $ 1.34万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06640474/
• 关键词: Frustration; Triangular Lattice Antiferromagnet; Kagome Lattice Antiferromagnet; Spin Fluctuation; Successive Phase Transition; Nuclear Magnetic Resonance; Nuclear Magnetic Relaxation; Relaxation Time; 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.

利用核磁共振谱和核磁弛豫时间研究了受挫反铁磁体的相变、自旋结构和涨落。三角形晶格Heisenberg反铁磁体RbNiCl_3的磁性。(1)证实了连续相变，发现中间相温度范围仅为0.2K。(2) ^<87>Rb的核磁共振分裂可以用电四极相互作用解释，其中包括高达二阶扰动。(3)提出了低温相自旋结构和自旋间相互作用的新模型。(4)通过测量各相的弛豫时间，阐明了受挫反铁磁体的特征涨落。在具有小易轴各向异性的三角形晶格Heisenberg反铁磁体CsNiBr_3(1)中测量了顺磁相、分量无序相和三角形有序相的自旋晶格弛豫时间和电子自旋涨落。(2)发现三角形有序相存在摆动涨落，这种涨落的双磁振子过程有助于核弛豫。(3)通过弛豫时间揭示了顺磁相位的特征波动。Kagome晶格反铁磁体AFe_3(OH)_6(SO_4)_2 （A=NH_4, Na， K）的磁性及涨落。(1)首次在Kagome晶格反铁磁体中观察到连续相变。(2)通过测量^1H nad ^<23> Na的核磁共振波谱来考虑各相的自旋结构。(3)发现了Kagome晶格反铁磁体的特征涨落。

项目成果

小山田明: "NQR Studies of the Structural Instabilities in CePb_2Al_3" Physica B. 206. 237-239 (1995)

Akira Oyamada：“CePb_2Al_3 结构不稳定性的 NQR 研究”Physica B. 206. 237-239 (1995)

S.MAEGAWA: "Observation of Successive Phase Transitions in Kagome Lattice Antiferromagnets AFe_3(OH)_6(SO_4)_2 (A=NH_4, Na, K)" Journal of Physical Society of Japan. (submitted to). (1996)

S.MAEGAWA：“戈薇晶格反铁磁体 AFe_3(OH)_6(SO_4)_2 (A=NH_4，Na，K) 中连续相变的观察”日本物理学会杂志。

河本敏郎: "Sublattice Switching in the Three-Dimensional Ordered Phase of the Triangular-Lattice Antiferromagnet CsCoCl_3" Physical Review B. 52. 12526-12529 (1995)

Toshiro Kawamoto：“三角晶格反铁磁体 CsCoCl_3 三维有序相中的亚晶格切换”物理评论 B. 52. 12526-12529 (1995)

S.MAEGAWA: "Magnetic Properties and Phase Transition in Kagome Lattice Antiferromagnets" Report of the Institute of Solid State Physics. (in press). (1996)

S.MAEGAWA：固体物理研究所的“戈薇晶格反铁磁体的磁性和相变”报告。

前川覚: "Spin Fluctuation in a Triangular Lattice Antiferromagnet CsNiBr_3 Studied by NMR" Journal of Magnetism and magnetic Materials. 140. 1789-1790 (1995)

Satoru Maekawa：“通过 NMR 研究三角形晶格反铁磁体 CsNiBr_3 中的自旋涨落”《磁性与磁性材料杂志》140。1789-1790 (1995)。