Abstract
The magnetocaloric effect (MCE) of Ni0.4Mg0.3Cu0.3Fe2O4 ferrite was analyzed by different theoretical methods such as mean-field, Bean-Rodbell and Landau theories. Results confirm the second order type of the ferromagnetic (FM)-paramagnetic (PM) magnetic phase transition for the sample. The values of magnetic entropy change (-Delta S-M) estimated from each theory agree well with those experimentally determined using Maxwell relations. The spontaneous magnetization values (M-spont(T)) determined from both (-Delta S-M versus M-2) and (H/M versus M-2) data are very close, confirming the validity of the magnetic entropy change to estimate M-spont (T) values. The critical exponents (beta, gamma and delta) obtained for Ni0.4Mg0.3Cu0.3Fe2O4 sample at its Curie temperatures (T-C) are close to those predicted in mean-field model.