Electron correlations in kagome metals $AV_3Sb_5$ (A= K, Rb, Cs)

Abstract

The investigation of electronic order-quantum phase interplay in kagome lattices commonly employs the extended Kagome-Hubbard model, where the critical parameters comprise on-site $(U)$ and intersite $(V)$ Coulomb interactions. In prototypical kagome metals \ch{AV3Sb5} (A = K, Rb, Cs), the geometrically frustrated quasi-2D architecture induces pressure-dependent complexity in vanadium d-electron correlations, necessitating systematic theoretical scrutiny. Utilizing the $d-dp$ model within constrained random phase approximation (cRPA), we quantified $U$, $V$, and Hund's coupling $J$ under hydrostatic pressure (0-9 GPa). While \ch{KV3Sb5} and \ch{RbV3Sb5} exhibit pressure-insensitive interaction parameters, \ch{CsV3Sb5} manifests anomalous discontinuities in $U$ and $V$ near $0.2$ GPa, suggesting a first-order electronic phase transition. This work establishes cRPA-derived interaction landscapes as critical predictors for pressure-tunable quantum phenomena in correlated kagome systems, offers a new insight into the understanding of the interplay between the CDW transition and the double superconductivity dome in \ch{CsV3Sb5} at low pressure.