稀土ErCrO_3多铁性材料的结构与温度依赖的磁特性研究

Structure and the dependence of magnetic properties on temperature for rare earth ErCrO_3 chromites

系统研究了稀土ErCrO3铬氧化物的结构与磁特性,结果表明,室温下实验样品ErCrO3呈正交的单相结构(Pbnm群);从热磁曲线M-T结合不同温度下的磁滞回线结果发现,在T>133K的高温区体系表现出典型的顺磁特性,其直流磁化率倒数随温度的变化很好地遵从居里-外斯定律,由此拟合可给出体系的有效平均磁矩μeff=10.57μB、顺磁居里温度Tcw=-30K。随温度降低,在133K以下样品呈现出弱铁磁的Г4(Fx)相,即铁磁相变温度为TN≈133K;当温度进一步降低到约20K,样品ErCrO3经历了从Г4(Fx)弱铁磁到反铁磁相Gy或Г1(0)的转变,并呈现出自旋重新取向特征;结合ErCrO3结构特征,这一温度依赖的复杂磁特性反映了Cr3+-Cr3+、Cr3+-Er3+和Er3+-Er3+离子之间的交换耦合作用。

The rare earth ErCrO3 chromites have been systemically studied by structural and magnetic measurement.The results indicate that the samples show the perovskite-type ErCrO3 orthorhombic structure with space group Pbnm.The magnetic properties shown that ErCrO3 possess significant weak ferromagnetism below 133K.At TSR≈20K,ErCrO3 undergoes a spin reorientation from Г4（Ax,Fx,Cz） to Г1（Ax,Gy,Cz） or Г1（0） where the weak ferromagnetic moment disappears.And in the region of higher temperature T〉133K,the reciprocal of magnetic susceptibility χ-1 of ErCrO3 chromites behaves linearly indicating a typical curie-weiss behavior fitted.The effective magnetic moment μeff=10.57μB and asymptotic paramagnetic curie temperature Tcw=-30K,which suggests the predominance of antiferromagnetic interactions in ErCrO3 chromites.The current magnetization can be interpreted from the interaction between Cr^3＋-Cr^3＋,Cr^3＋-Er^3＋,Er^3＋-Er^3＋.