  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.
