Atomic-scale magnetic structure of magnetocaloric system MnSb investigated via magnetic pair distribution function analysis

We study the magnetic structure of materials in order to discover their unique characteristics, many of which form the foundation of important technologies in modern times. Obtaining a thorough understanding of the magnetic characteristics of materials requires studying their structure at the atomic level. Magnetic pair distribution function (mPDF) analysis of neutron scattering data is a powerful and reliable method for studying atomic-scale magnetic structures, especially for materials with complex magnetic configurations. Here, we present mPDF data on MnSb and several of its derivative compounds, which have attracted significant interest in recent years for their excellent and highly tunable magnetocaloric properties, which have potential applications in novel magnetic refrigeration and waste-heat recovery technologies. Using the open-source python package called diffpy to perform the mPDF analysis, we succeeded in modeling the atomic and magnetic structure of stoichiometric MnSb and variants with excess Mn over a large temperature range spanning the magnetic transition. We identified anomalies in the volume of the crystallographic unit cell and the orientation of the Mn spins, which we hypothesize originate from magnetostructural coupling in these materials. Our ongoing study of this interesting and technologically relevant system brings both confirmations and questions to the discussion surrounding these materials.