Effect of composition on magnetocaloric properties of Mn3Ga(1−x)SnxC

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\leq0.2 $) the MCE is of the inverse type wherein an increase in the applied field beyond 5T gives rise to a table like temperature dependence of the entropy due to a coupling between the first order FM - AFM transition and the field induced AFM - FM transition. Replacement of Ga by larger concentrations of Sn ($ x\geq0.71 $) $(\Delta S_M)$ results in a change of the MCE to a conventional type with very little variation in the position of $(\Delta S_M)_{max}$ 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.