Charge-loop current order and Z3 nematicity mediated by bond order fluctuations in kagome metals

Abstract

Recent experiments on geometrically frustrated kagome metal AV3Sb5 (A = K, Rb, Cs) have revealed the emergence of the charge loop current (cLC) order near the bond order (BO) phase. However, the origin of the cLC and its interplay with other phases have been uncovered. Here, we propose a novel mechanism of the cLC state, by focusing on the BO phase common in kagome metals. The BO fluctuations in kagome metals, which emerges due to the Coulomb interaction and the electron-phonon coupling, mediate the odd-parity particle-hole condensation that gives rise to the topological current order. Furthermore, the predicted cLC+BO phase gives rise to the Z3-nematic state in addition to the giant anomalous Hall effect. The present theory predicts the close relationship between the cLC, the BO, and the nematicity, which is significant to understand the cascade of quantum electron states in kagome metals. The present scenario provides a natural understanding.

Tuning charge density wave of kagome metal ScV6Sn6

“…The presence of an additional valence electron in Cr results in an upward shift of the E F by 120 meV [26]. This shift also causes the vHS to move further away from the E F , where the vHS is the primary reason for the loop current order in AV 3 Sb 5 systems [39][40][41][42].…”