Understanding the mutual influence of magnetism, elasticity, bonding, and weak interactions in FeCo4Sb12: A DFT+U, QTAIM, and NCI approach

Abstract

Despite the importance and particularity of filled-skutterudites with two transition metals, this field remains open for further investigation and many materials of this family remain still unexplored. In this work, several physical properties of FeCo₄Sb₁₂ have been studied for the first time. We have studied the electronic, magnetic, elastic properties and we have analyzed the different types of bonds and weak interactions and we have underlined, for each property, its link with the others. The obtained value of the lattice parameter a₀ using GGA-PBEsol is very close to the experimental one. The elastic study showed that FeCo₄Sb₁₂ is mechanically stable and the directional analysis of Young's modulus showed that it is elastically anisotropic. The magnetic and electronic study using GGA + U + SOC shows that FeCo₄Sb₁₂ has a nearly half-metallic behavior with a weak correlation between the electrons of d-subshells of Fe and Co, which can be explained by their strong delocalization. The study of bonding and non-covalent interactions, using QTAIM and NCI analyses, confirms this delocalization and shows that there are only three types of bonds: Fe-Sb, Co-Sb and Sb-Sb. The NCI analysis shows the absence of weak attractive interactions (vdW-type) but a presence of strong and weak repulsive ones.