Liquid-to-glass transition in the cluster-spin-glass Zn_0.5Co_0.5FeCrO₄

Abstract

The ac susceptibility and low field magnetization measurements indicate a magnetic ordering in the disordered spinel system Zn_0.5Co_0.5FeCrO₄ at T_f~147K with features typical of a 'cluster spin glass'. Although for T > T_f, the remanent magnetization is found to be nonzero, no Zeeman splitting is observed in the Fe⁵⁷ Mössbauer spectra at the same temperature. The spectrum gradually changes from a single line at T≫T_f to finally a broad sextuplet suggestive of a gradual evolution of spin clusters on lowering the temperature. The region T_f < T < 2T_f may be considered as a 'liquid like' state of the coupled spin system, where the clusters possess rotational freedom in the spin space which vanishes at T_f once they are frozen.