Scaling of the magnetic entropy change in spinel selenide CuCr2Se4

The magnetic entropy change (ΔSMΔSM) of the spinel selenide CuCr2Se4 has been thoroughly investigated around Curie temperature TC=430K. It is found that the temperature dependence of ΔSMΔSM under different applied fields H presents a unimodal shape only below 1 T, while the full width at half maximum δTFWHMδTFWHM becomes broad with the increase of H. We suggest that the suppression of the spin–orbit coupling between Cr3+ 3d electrons and Se 4p states by the external field should be responsible for the suppression of ΔSMΔSM. In addition, it is displayed that the maximum of ΔSMΔSM depends on Hn with n=0.63±0.05n=0.63±0.05 obtained by experiment, in agreement with that n=0.62±0.06n=0.62±0.06 deduced by the critical analysis. The relative cooling power [RCP(S)] increases with H   fulfilling the relation RCP(S)=aHbRCP(S)=aHb, where a=25.4±0.5 J/kg T and b  =0.93±0.08. With the scaling laws of ΔSMΔSM, the experimental ΔSM(T,H)ΔSM(T,H) collapse onto a universal curve, where an average curve is obtained. With the phenomenological universal curve, the experimental ΔSM(T,H)ΔSM(T,H) are well predicted.