(中南大學(xué) 物理科學(xué)與技術(shù)學(xué)院， 長(zhǎng)沙 410083)
摘 要: 采用分子場(chǎng)理論模型對(duì)稀土-過(guò)渡族金屬間化合物的磁性、 自旋重取向相變和場(chǎng)誘導(dǎo)的一級(jí)磁相變進(jìn)行了研究。從理論上計(jì)算了TbMn6Sn6的易磁化方向隨溫度的變化以及不同溫度時(shí)的磁化曲線，描述了自旋重取向相變和場(chǎng)誘導(dǎo)的一級(jí)磁相變。 基于單離子模型計(jì)算了Tb離子和化合物的一階和二階磁晶各向異性常數(shù)及其隨溫度的變化，得到了和實(shí)驗(yàn)數(shù)據(jù)基本一致的結(jié)果。 結(jié)果表明： Mn次晶格和Tb次晶格磁晶各向異性能之間的相互競(jìng)爭(zhēng)是導(dǎo)致自旋重取向相變的物理機(jī)制，而稀土離子的四階晶場(chǎng)項(xiàng)對(duì)場(chǎng)誘導(dǎo)的一級(jí)磁相變產(chǎn)生很大的影響。
關(guān)鍵字: 稀土-過(guò)渡族金屬間化合物； 自旋重取向； 磁相變； 磁晶各向異性
（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
