(中南大学 物理科学与技术学院， 长沙 410083)
摘 要: 采用分子场理论模型对稀土-过渡族金属间化合物的磁性、 自旋重取向相变和场诱导的一级磁相变进行了研究。从理论上计算了TbMn6Sn6的易磁化方向随温度的变化以及不同温度时的磁化曲线，描述了自旋重取向相变和场诱导的一级磁相变。 基于单离子模型计算了Tb离子和化合物的一阶和二阶磁晶各向异性常数及其随温度的变化，得到了和实验数据基本一致的结果。 结果表明： Mn次晶格和Tb次晶格磁晶各向异性能之间的相互竞争是导致自旋重取向相变的物理机制，而稀土离子的四阶晶场项对场诱导的一级磁相变产生很大的影响。
关键字: 稀土-过渡族金属间化合物； 自旋重取向； 磁相变； 磁晶各向异性
（School of Physics Science and Technology,
Central South University, Changsha 410083, China）
Abstract: The molecular field theory of exchange interaction was applied to investigate the magnetic properties, spin-reorientation transition and field-induced magnetic phase transitions of intermetallic compound TbMn6Sn6. The temperature dependence of easy magnetization direction and magnetic curves at different temperatures were calculated. The theoretical results have good agreement with the experimental data. In the framework of single ion model the magnetocrystalline anistropic constants and their temperature dependence of compound were calculated. The results show that the competition between the magnetocrtstalline anistropic energy of Tb and Mn sunlattices gives rise to the spin-reorientation transition. The fourth-order crystal field parameter (B04) of Tb ion plays an important role on the field-induced magnetic phase transition.
Key words: rare earth-transition intermetallic compound; spin-reorientation transition; magnetic phase transition; magnetocrystalline anisotropy
