Packing fraction related distortion of Mn6C octahedra and its effect on the first order magnetic transition in Mn based antiperovskites

Abstract

In this paper, we attempt to understand the cause of magnetostructural transformation in Mnbased antiperovskites by calculating EXAFS at the K edges of constituent metal atoms in three antiperovskite compounds, Mn 3 GaC, Mn 3 SnC and Mn 3 InC. These three compounds have very different magnetic ground states despite the similar cubic structure. Our calculations show that the distortions of Mn 6 C octahedra, which are responsible for the first-order magnetic transition to antiferromagnetic state, depends on the packing fraction of the lattice.

Competing Magnetic Interactions, Structure and Magnetocaloric Effect in Mn3sn1-Xznxc Antiperovskite Carbides

“…The magnetic behaviour of the Mn 3 Sn 1-x Zn x C compounds with x ≥ 0.4 resembles Mn 3 ZnC, for which two subsequent transitions can be observed. Recent studies revealed the influence of the packing fraction on the local distortions of the Mn 6 C octahedra, leading to long and short Mn-Mn distances, while the cubic structure remains unaltered [23,44,45]. With increasing Zn content, the packing fraction decreases, which results in more space for the distortion of the Mn 6 C octahedra.…”