Effect of composition on magnetocaloric properties of Mn${}_3$Ga${}_{(1-x)}$Sn${}_x$C

Abstract

A study investigating the effect of Sn substitution on the magnetocaloric properties of Mn${}_3$Ga${}_{(1-x)}$Sn${}_x$C compounds reveals that nature of the MCE has a strong dependence on the nature of the magnetic ordering. For small amounts of Sn ($x\le 0.2$) the MCE is of the inverse type wherein an increase in the applied field beyond 5T gives rise to a table like temperature dependence of the entropy due to a coupling between the first order FM - AFM transition and the field induced AFM - FM transition. Replacement of Ga by larger concentrations of Sn ($x\ge 0.71$) $(\hat{I}”S_M)$ results in a change of the MCE to a conventional type with very little variation in the position of $(\hat{I}”S_M{)}_{max}$ with increasing magnetic field. This has been explained to be due to the local strain introduced by A site ions (Ga/Sn) which affect the magnetostructural coupling in these compounds.

7 pages 7 figures, Accepted for publication in J. Appl. Phys