金属间化合物DyMn2Ge2的自发磁相变和场诱导的磁相变  

SPONTANEOUS AND FIELD-INDUCED MAGNETIC PHASE TRANSITIONS IN THE INTERMETALLIC COMPOUND DyMn2Ge2

作　　者：郭光华[1] Levi.,RZ 

机构地区：[1]中南工业大学应用物理与热能工程系，长沙410083 [2]Department

出　　处：《物理学报》2001年第2期313-318,共6页Acta Physica Sinica

摘　　要：在10—800K的温度范围内用X射线衍射方法测量了DyMn2Ge2化合物的晶格常数与温度的变化关系，观察到高温时DyMn2Ge2由顺磁状态到反铁磁状态的自发磁相变伴随着晶格常数a的负的磁弹性异常现象. 在4.2K—200K的温度范围内测量了DyMn2Ge2的交流磁化率. 在交换相互作用的分子场模型近似下，从理论上分析讨论了DyMn2Ge2的低温自发磁相变和场诱导的磁相变. 计算了DyMn2Ge2单晶的磁化强度与温度的变化关系以及不同温度下外磁场沿晶轴c方向时的磁化曲线. 理论分析和计算结果表明，温度低于33K时在DyMn2Ge2中观察到的场诱导的一级磁相变为由亚铁磁状态(Fi)到中间态(IS)相变.The temperature dependence of lattice constants a and c of intermetallic compund DyMn2Ge2 is measured in the temperature range 10 - 800K by using the X-ray method. The magnetoelastic anomaly of lattice constants a is observed at spontaneous magnetic phase transition from paramagnetic state to antiferromagnetic state. The sc magnetic susceptibility of DyMn2Ge2 is measured in the temperature range 4.2 - 200K. Low temperature magnetic phase transitions in DyMn2Ge2 are discussed in the molecular field approximation by taking into account of next nearest Mn-Mn interlayer exchange interaction. The temperature dependence of magnetization and magnetic curves at different temperatures of DyMn2Ge2 single crystal are calculated. Theoretical calculation shows that the observed field-induced magnetic phase transition in DyMn2Ge2 single crystal at temperature lower than 33K is the transition from ferrimagnetic state into intermediate state.

关 键 词：稀土-过渡族金属间化合物 磁结构 磁相变 场诱导 

分 类 号：O73[理学—晶体学]