Magnetic properties and magnetic entropy change in spinels (Cd,M)Cr2S4 with M=Cu or Fe

Abstract

Magnetic properties and magnetic entropy changes in spinels $(\mathrm{Cd},M){\mathrm{Cr}}_2{\mathrm{S}}_4$ with $M=\mathrm{Cu}$ or Fe have been studied. The saturation moments per formula unit are about $4.77{\mu }_B$ for ${\mathrm{Cd}}_{0.8}{\mathrm{Cu}}_{0.2}{\mathrm{Cr}}_2{\mathrm{S}}_4$ and $4.41{\mu }_B$ for ${\mathrm{Cd}}_{0.7}{\mathrm{Fe}}_{0.3}{\mathrm{Cr}}_2{\mathrm{S}}_4$ . Magnetic transition in Cu- and Fe-doped samples are of second order in nature, and their Curie temperatures are $T_C=86$ and $119\mathrm{K}$ , respectively. The maximum values of magnetic entropy change $\Delta S$ are found to be 5.1 and $5.4\mathrm{J}∕\mathrm{kg}\mathrm{K}$ for ${\mathrm{Cd}}_{0.8}{\mathrm{Cu}}_{0.2}{\mathrm{Cr}}_2{\mathrm{S}}_4$ and ${\mathrm{Cd}}_{0.7}{\mathrm{Fe}}_{0.3}{\mathrm{Cr}}_2{\mathrm{S}}_4$ for a field change from $0\text{to}5\mathrm{T}$ , respectively. The significant $\Delta S$ suggests a potential of the sulfospinel as a magnetic refrigerant in the corresponding temperature range.