Exchange bias and magnetization reversal in Ni(Cr1−xFex)2O4 (x=0–0.20)

Abstract

Exchange bias and magnetization reversal in single phase samples of Ni(Cr1−xFex)2O4 (x=0–0.20) were studied through magnetic measurements. Substitution of Fe for Cr changes the crystal structure at room temperature from tetragonal (space group: I41/amd) to cubic (space group: Fd3¯m) form. Temperature variation of magnetization measurements show that these samples undergo ferrimagnetic transitions and the transition temperature (TC) increases from 73K for x=0.0 to 314K for x=0.20. An interesting magnetization reversal phenomenon was observed for x=0.06 sample with a magnetic compensation temperature of 49K. M–H loop measurements at different temperature show the signature of presence of strong antiferromagnetic interactions especially at low temperature (T<50K). Tunable exchange bias behavior with a maximum exchange bias field of 5670Oe is observed for x=0.06 sample and it is explained by considering the exchange anisotropy between the ferrimagnetic and the antiferromagnetic components. The exchange bias field and the vertical shift in magnetization decrease exponentially with increase in temperature.