Effect of Zn substitution on the magnetic and magnetocaloric properties of Cd1−xZnxCr2Se4 spinel

Abstract

The influence of Zn substitution on the magnetic and magnetocaloric properties of Cd_1−xZn_xCr₂Se₄ (0.35 ≤ x ≤ 0.45) spinel was investigated. All the samples exhibited two successive magnetic transitions associated with the reentrant spin glass at a freezing temperature (T_f) and Curie temperature (T_C). It was demonstrated that T_f changed slightly with the Zn content; however, the T_C value decreased with increasing Zn content due to the decrease of lattice constant. The magnetic entropy variation (−ΔS_M) was found to exhibit two maxima at T_C and T_f, which have an opposite trend as a function of Zn content. With increasing Zn content, (−ΔS_M) was found to decrease at T_C, whereas at T_f, (−ΔS_M) increased. It was shown that the change of (−ΔS_M) is closely correlated to the local exponent factor n at both transitions. The results showed that materials with double magnetic transitions could be integrated in a new class of magnetic refrigeration working in different temperature windows.