A‑Site and Epitaxial Strain Effect on the Properties of AMn3Sb5 (A = K, Cs, and Rb) Kagome Lattices.

Kagome lattices are an exciting family of compounds where frustrated magnetism, superconductivity, charge density wave (CDW) orders, topological features, large anomalous Hall conductivity, flat bands, and van Hove singularities collide. With this in mind, we theoretically studied the Mn-based Kagome AMn3Sb5 (A = K, Rb, and Cs) lattices and explored the A-site's influence, as well as the epitaxial xy-strain effect on the structural, magnetic, and electronic properties. Through theoretical analysis, coupled with first-principles density functional theory calculations, we demonstrate that the entire family is dynamically stable, locking the ferromagnetic order as the ground-state configuration in the primitive cell and preventing charge-density wave condensation, as observed in the AV3Sb5 family. In these compounds, our results suggest an out-of-plane ferromagnetic response that, in turn, breaks the T -symmetry, allowing a nonzero Berry curvature. The latter leads to a symmetry-allowed anomalous Hall conductivity (σ αβ ) as large as σ xy = 402 S·cm-1 in the CsMn3Sb5 and σ xy = 442 S·cm-1 under +3% in-plane epitaxial strain.