Critical behavior’s and spontaneous magnetization’s estimation through magnetic entropy change in CoFeCuO 4 spinel ferrite

Abstract

Abstract In this work we are basically interested in the critical behavior study of the CoFeCuO4 spinel ferrite and the determination of its spontaneous magnetization through magnetic entropy change. This sample was prepared by the sol-gel method, the Rietveld refinement of X-ray diffraction proves the cubic spinel structure with the Fd3̅m space group. Besides, the second order ferromagnetic (FM)/paramagnetic (PM) phase transition is exhibited by the studied compound at a Curie-temperature TC= 688K. The magnetic entropy change (ΔSM) is evaluated based on Maxwell relations. Its maximum value at μ0H = 5 T is 0.6 J.kg-1.K-1 , it corresponds to a value of 64.34 J.kg-1 for the relative cooling power (RCP), which makes our sample as a promising material for the magnetic refrigeration (MR) technology. The critical exponents 𝛽 , 𝛾 and 𝛿 are deduced from the field dependence of the magnetic entropy change and the relative cooling power. The found values aren’t in good agreement with those found according to (MAP), (K-F) and (CIA) methods. The spontaneous magnetization values determined through the magnetic entropy change (ΔSM vs. M2) aren’t in good agreement with those corresponding to the classical extrapolation of arrott curves (μ0H/M vs. M2). Subsequently, using the magnetic entropy change for the critical behavior and spontaneous magnetization study in CoFeCuO4 spinel ferrite isn’t well appropriate.