Interlocked Vortex Order in the Frustrated $A_3$V$_9$Te$_{13}$ Lattice ($A$=Cs,Rb)

Abstract

Recently synthesized $A_3$V$_9$Te$_{13}$ ($A$ = Cs, Rb) provides a unique platform for exploring the interplay between geometric frustration, magnetism, and correlated electronic states beyond conventional kagome systems. Based on first-principles calculations, we demonstrate that the frustrated V sublattice naturally stabilizes a robust vortex or anti-vortex antiferromagnetic ground state, whose total energy is substantially lower than all other configurations. In addition, the Heisenberg model analysis show strong constraints on the ground state magnetic configuration, such that fixing spin configuration of 1 triangle propagates and fixes all others. The vortex or anti-vortex phase hosts electronic structures reminiscent of kagome metals, including Dirac-like band crossings, van Hove singularities, and flat bands near the Fermi level. Owing to the noncollinear spin texture and quasi-two-dimensional magnetic character, the Néel temperature exhibits an extremely weak dependence on both the magnitude and direction of external magnetic fields, consistent with experimental observations. For Cs-based compound, the ground state band structure is metallic with 6 Weyl points in the BZ; while for the Rb-based compound, spin--orbit coupling opens an approximately 27-meV gap at ambient pressure due to the lifted C$_3$ symmetry. Our results establish $A_3$V$_9$Te$_{13}$ as a promising platform for studying frustration-driven chiral magnetism and its interplay with topological electronic states.