Charge-loop current order and Z3 nematicity mediated by bond-order fluctuations in kagome metal AV3Sb5 (A=Cs,Rb,K)

TL;DR

This paper proposes a new mechanism for charge loop current order in kagome metals, linking bond order fluctuations to topological charge currents and nematicity, explaining experimental observations like the anomalous Hall effect.

Contribution

It introduces a novel theoretical framework connecting bond order fluctuations to charge loop currents and Z3 nematicity in kagome metals.

Findings

Charge loop current order is mediated by bond order fluctuations.

The cLC+BO phase leads to Z3-nematicity and giant anomalous Hall effect.

The theory explains the relationship between charge currents, bond order, and nematicity.

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 relation to other phases have been uncovered. Here, we discover a novel mechanism of the cLC state, by focusing on the BO phase common in kagome metals. The BO fluctuations in metals mediate the odd-parity particle-hole condensation, which drives the topological charge-current. This state is further stabilized by the finite electron-phonon coupling and the off-site Coulomb interaction. Furthermore, it is worth noting that 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.