Anomaly in cluster glass behaviour of Co0.2Zn0.8Fe2O4 spinel oxide

Abstract

We report cluster glass behaviour mixed with short-range ferrimagnetic ordering in Co0.2Zn0.8Fe2O4 spinel oxide. The AC susceptibility data show a maximum at Tf1≈110K and a shoulder at Tf2≈212K. The DC magnetization data also show a maximum at Tm1≈110K and a shoulder at Tm2≈260K. The frequency dependence of AC susceptibility and field dependence of DC magnetization data suggest a cluster spin-glass freezing at Tf1≈110K. The appearance of shoulder in AC susceptibility data at Tf2≈212K can be explained in terms of freezing of larger size clusters associated with anisotropy distribution. This is a pseudo-phase transition related to cluster size effect, rather than spin-glass-like freezing. The AC susceptibility, DC magnetization and room temperature Mössbauer spectroscopy measurements suggest that above 260K the magnetic phase is dominated by short-range interacting clusters in paramagnetic state, called cluster-paramagnetic phase and at 110K<T⩽260K short-range ferrimagnetic phase coexist with cluster spin-glass phase, called mixed magnetic phase, in the present system.