Coexistence of spin glass and superparamagnetism with ferrimagnetic order in polycrystalline spinel [formula omitted

Abstract

We discuss our investigation of DC magnetization, as a function of time, temperature and magnetic field, and explore some distinct magnetic behaviour in the polycrystalline spinel Co 0.2Zn 0.8Fe 1.95Ho 0.05O 4. The system is essentially to be a ferrimagnet and the ferrimagnetic order (spontaneous magnetization) is identified using Arrot plot of M ( H ) data. Application of some scaling laws have shown the coexistence of spin glass (SG) and superparamagnetism (SPM) with ferrimagnetic order (FIMO) at low and high temperature, respectively, in the system. The coexistence of SG and SPM with FIMO shows paramagnetic to ferrimagnetic state at T C ≈ 225 K and ferrimagnetic to cluster spin glass state below T m ≈ 120 K . The non-linear increase, without hysteresis, of M ( H ) data above T C indicates the existence of short range interacting clusters in the paramagnetic state. In addition, the anisotropy effect of Ho 3+ has shown some interesting magnetic features, such as, spin glass of Ising nature and an unusual maximum in the thermoremanent magnetization about 180 K.