关于海森堡反铁磁链材料LiVGe_2O_6有限温度相变的理论研究  

Analysis of the finite-temperature phase transition of Heisenberg antiferromagnetic compound LiVGe_2O_6

作　　者：黄海[1] 李伟锋[1] 

机构地区：[1]华北电力大学数理学院,北京102206

出　　处：《物理学报》2013年第21期344-349,共6页Acta Physica Sinica

基　　金：中央高校基本科研业务费专项基金(批准号:12ZP11;13TD03)资助的课题~~

摘　　要：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Ne′el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.The susceptibility and nuclear magnetic resonance measurements on quasi-one-dimensional spin-1 Heisenberg antiferromagnet LiVGe206 indicate that this material shows a phase transition from paramagnetic state to antiferromagnetic N6el state at about 22 K, and there exists a gap in the low-temperature magnetic excitation spectrum. Based on the model Hamiltonian of LiVGe206, 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 LiVGe206. All the theoretical calculations are consistent with the experimental results.

关 键 词：海森堡模型 O(3)非线性仃模型 有限温度相变 

分 类 号：TM271.6[一般工业技术—材料科学与工程]