Magnetic exchange interactions in kagome metal KMn₃Sb₅

Abstract

The concept of electronic topology and the associated topological protection brings great opportunity for developing next-generation spintronics devices, especially those requiring high quantum-mechanical coherence properties. Among these, different types of topological kagome materials have attracted attention because they exhibit a wide range of exotic quantum states, such as charge density wave (CDW), chiral non-collinear magnetic orderings, etc. KMn₃Sb₅, a new ferromagnetic (FM) kagome material, belongs to the same family as well-known CDW kagome materials like AV₃Sb₅ (A = K, Rb, and Cs). Although FM-KMn₃Sb₅ was predicted to be a non-trivial topological material with considerable anomalous Hall response, the presence of strongly correlated Mn:3d valence electrons necessitates further examinations. Our first-principles density-functional theory (DFT+U) calculations unveil an A-type antiferromagnetic (AFM) order in KMn₃Sb₅, which is sensitive to the strength of the onsite Coulomb interaction parameter U. A tight-binding Hamiltonian is constructed to evaluate Heisenberg exchange-interaction parameters and unveil the magnetic configuration of this complex system. We further discuss the role of electronic correlations on the electronic structure of AFM-KMn₃Sb₅.