化合物HoMn6Sn6的磁晶各向异性及自旋重取向相变研究

采用交换相互作用的分子场理论模型对金属间化合物HoMn₆Sn₆的自旋重取向相变进行了研究. 从理论上计算了HoMn₆Sn₆的易磁化方向以及Ho和Mn离子磁矩与c轴夹角随温度的变化. 基于单离子模型计算了Ho离子的一阶和二阶磁晶各向异性常数K_1R和K_2R随温度的变化. 研究表明，为了很好描述该化合物的自旋重取向相变，必须考虑Ho离子的四阶晶场项及相应的二阶磁晶各向异性常数K_2R，K_2R与K_1R和Mn离子磁晶各向异性常数K_1t之间的相互竞争是导致HoMn₆Sn₆自旋重取向相变的重要因素. 关键词： 稀土-过渡族金属间化合物 自旋重取向 磁晶各向异性

Magnetocrystalline anisotropy and spin-reorientation transition of intermetallic compound HoMn6Sn6

The molecular field theory of exchange interaction has been applied to investigate the spin-reorientation transition in intermetallic compound HoMn₆Sn₆. The theoretically calculated temperature dependence of easy magnetization direction is in good agreement with experimental data. The temperature dependence of magnetocrystalline anistropic constants of Ho ion K_1R and K_2R have been calcullated in the framework of single ion model. It is shown that the fourth-order crystal field parameter B⁰₄ and the corresponding second-order magnetocrystalline anistropic constant K_2R of Ho ion have to be taken into account in order to explain the spin-reorientation transition. The competition between K_2R and K_1R plays an important role in the spin-reorientation transition in HoMn₆Sn₆.