Role of Tin and Carbon in the magnetic interactions in Mn${}_3$SnC

In this paper we attempt to understand the role of tin and carbon in magnetic interactions in Mn${}_3$SnC. Mn${}_3$SnC exhibits a time dependent magnetic configuration and a complex magnetic ground state with both ferromagnetic and antiferromagnetic orders. Such a magnetic state is attributed to presence of distorted Mn${}_6$C octahedra with long and short Mn–Mn bonds. Our studies show that C deficiency increases the tensile strain on the Mn${}_6$C octahedra which elongates Mn–Mn bonds and strengthens ferromagnetic interactions while Sn deficiency tends to ease out the strain resulting in shorter as well as longer Mn–Mn bond distances in comparison with stoichiometric Mn${}_3$SnC. Such a variation strengthens both, ferromagnetic and antiferromagnetic interactions. Thus the structural strain caused by both Sn and C is responsible for complex magnetic ground state of Mn${}_3$SnC.