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

The influence of Zn substitution on the magnetic and magnetocaloric properties of Cd-1- xZnxCr2Se4 (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 Tf 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 (-Delta S-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, (-Delta S-M) was found to decrease at T-C, whereas at T-f, (-Delta S-M) increased. It was shown that the change of (-Delta S-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.