自旋玻璃的重入行为及Co_xZn(1-x)(Fe_yCr(1-y))_2O_4尖晶石系统的磁相图

REENTRANT BEHAVIOUR OF SPIN GLASS AND THE MAGNETIC PHASE DIAGRAM OF A SPINEL SYSTEM Co_xZn_1-x(Fe_y-Cr_1-v)_2O_4

本文研究了Co_xZn-(1-x)(Pe_yCr(1-x)_2O_4尖晶石系统的磁性,测量了不同成份样品的低频弱场交流磁化率与低场直流磁化强度的温度关系。根据实验结果,给出了该系统可能的磁相图。发现在该系统中相当宽的成份范围内,都存在自旋玻璃的重入现象。同时发现,自旋玻璃的重入温度随磁性离子浓度增加而增加。这些行为是磁性离子浓度含量较高和多种磁性离子共存系统的共同特性。还讨论了自旋玻璃重入行为的机制。认为该尖晶石系统中的重入自旋玻璃态,是由亚铁磁长程序解体而形成的大量亚铁磁微畴或自旋团与自旋玻璃共存的状态。

A study of magnetic properties in the insuluing spinel system CozZn1-x(FeyCr1-v)2O4has been made based on the temperature relationships of the low-frequency, weak field ac susceptibilities and low field magnetizations measurements. According to the above experimental results, we propose a probable magnetic phase diagram of the spinel. This magnetic phase diagram shows the reentrant spin glass phenomena in quite wide concentration ranges in the spinel. Increasing the concentration of the magnetic ions, the freezing temperatures of the reentrant spin glass increase. These properties are common in the systems with a few kinds of the magnetic ions or the magnetic ions which concentration are quite high. The mechanism of reentrance of spin glasses has been discussed in the paper. The reentrant spin glass in the spinel is a mixed state of spin glass and ferrimagnetic microdomains or spin clusters, which come from the collapse of the ferrimagnetic state.