Phase separation and effect of strain on magnetic properties of Mn${}_3$Ga${}_{1-x}$Sn${}_x$C

While the unit cell volume of compounds belonging to the Mn${}_3$Ga${}_{1-x}$Sn${}_x$C, (0 $\le x\le$ 1) series shows a conformity with Vegard’s law, their magnetic and magnetocaloric properties behave differently from those of parent compounds Mn${}_3$GaC and Mn${}_3$SnC. A correlation between the observed magnetic properties and underlying magnetic and local structure suggests that replacing Ga atoms by larger atoms of Sn results in the formation of Ga-rich and Sn-rich clusters. As a result, even though the long range structure appears to be cubic, Mn atoms find themselves in two different local environments. The packing of these two different local structures into a single global structure induces tensile/compressive strains on the Mn${}_6$C functional unit and is responsible for the observed magnetic properties across the entire solid solution range.