Effect of Zn substitution on the magnetic and magnetocaloric properties of Cd 1-x Zn x Cr 2 Se 4 spinel.

The influence of Zn substitution on the magnetic and magnetocaloric properties of Cd1-x Znx Cr2 Se4 (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 (Tf ) and Curie temperature (TC ). It was demonstrated that Tf changed slightly with the Zn content; however, the TC value decreased with increasing Zn content due to the decrease of lattice constant. The magnetic entropy variation (-ΔSM ) was found to exhibit two maxima at TC and Tf , which have an opposite trend as a function of Zn content. With increasing Zn content, (-ΔSM ) was found to decrease at TC , whereas at Tf , (-ΔSM ) increased. It was shown that the change of (-ΔSM ) 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.