Effect of Anisotropy on Magnetic Ordering in the Spinel System CoZn<sub>z</sub>Ge<sub>z</sub>Cr<sub>x-z</sub>Fe<sub>2-x-z</sub>O<sub>4</sub>

Abstract

The spinel ferrite system CoZnzGezCrx-zFe2-x-zO4with z= x2;x = 0.60, 0.65 and 0.70 was studied by Mà T (ZFC-FC) DC magnetization at low and high fields in the temperature range 5K to 300K, MàH measurements with high field up to 55 kOe at 15K temperature and low field AC susceptibility in temperature range 77K to 300K. We observe thermo-magnetic irreversibility (TMI) in MàT study, high field slope with high coercivity in MàH study. The composition x = 0.70 shows constricted hysterisis loop at 15K. We observed a cusp at transition temperature in AC susceptibility measurements. We have shown that the features observed in all these measurements are adequately explained using domain wall dynamics and inherent magneto-crystalline anisotropy without invoking the concept of cluster spin-glass type ordering in x = 0.60 and x = 0.65 in temperature range 5K to 300K. The sample x= 0.70, however showed signatures of cluster spin-glass type of ordering at low temperature as revealed in non-Brillouin type shape of low field FC curves in MàT DC magnetization and constricted hysterisis loop at 15K temperature.