Absence of first order magnetic transition, a curious case of Mn3InC
Abstract
The volume expanding magnetostructural transition in Mn3GaC and Mn3SnC has been identified to be due to distortion of Mn6C octahedra. Despite a similar lattice volume as Mn3SnC and similar valence electron contribution to the density of states as in Mn3GaC, Mn3InC does not undergo a first order magnetostructural transformation like the Ga and Sn antiperovskite counterparts. A systematic investigation of its structure and magnetic properties using probes like x-ray diffraction, magnetization measurements, neutron diffraction and extended x-ray absorption fine structure (EXAFS) reveal that though the octahedra are distorted resulting in long and short Mn -- Mn bonds and different magnetic moments on Mn atoms, the interaction between them remains ferromagnetic. This has been attributed to the strain on the Mn6C octahedra produced due to the relatively larger size of In atom compared to Sn and Ga. The size of In atom constricts the deformation of Mn6C octahedra giving rise to Mn -- Mn distances that favor only ferromagnetic interactions in the compound.