关于海森堡反铁磁链材料LiVGe2O6有限温度相变的理论研究

自旋s=1的海森堡反铁磁链材料LiVGe₂O₆的磁化率以及 核磁共振实验表明该材料在临界温度约为22 K时由顺磁相转变为反铁磁Néel相, 且低温磁激发谱存在能隙. 本文在已有模型哈密顿量的基础上提出了一个低能场论模型——Ginzburg-Landau理论来描述 这一反铁磁链材料, 并运用这一理论讨论了LiVGe₂O₆由于自发对称性破缺导致的有限温度相变及 相应的磁化率变化情况, 理论计算很好地解释了现有的实验结果.关键词：海森堡模型σ模型')" href="#">O(3)非线性σ模型有限温度相变

Analysis of the finite-temperature phase transition of Heisenberg antiferromagnetic compound LiVGe2O6

The susceptibility and nuclear magnetic resonance measurements on quasi-one-dimensional spin-1 Heisenberg antiferromagnet LiVGe₂O₆ indicate that this material shows a phase transition from paramagnetic state to antiferromagnetic Néel state at about 22 K, and there exists a gap in the low-temperature magnetic excitation spectrum. Based on the model Hamiltonian of LiVGe₂O₆, we propose a low-energy field theory——Ginzburg-Landau theory for this compound. From this theory, we study the finite-temperature phase transition induced by spontaneous symmetry breaking and then calculate the finite-temperature susceptibility of LiVGe₂O₆. All the theoretical calculations are consistent with the experimental results.
Keywords：Heisenberg modelσ model')" href="#">O(3) non-linear σ modelfinite-temperature phase transition