Surface acoustic wave-driven valley current generation in intervalley coherent states

TL;DR

This paper demonstrates that intervalley coherent states in rhombohedral graphene can generate anomalous valley currents when driven by surface acoustic waves, revealing new valleytronics phenomena linked to symmetry breaking.

Contribution

It introduces a theoretical framework showing how IVC order induces valley-current generation via SAWs, highlighting a novel mechanism for valleytronics in graphene.

Findings

Valley current exhibits power-law dependence on low-frequency SAWs.

IVC order enhances valley-current generation in rhombohedral graphene.

Results suggest potential for exploring exotic valley-gauge-symmetry-breaking phenomena.

Abstract

Recent experiments have reported valley-gauge-symmetry-broken phases, identified as intervalley coherent (IVC) states. Exploration of anomalous responses, particularly those analogous to superconductivity, has become an urgent theoretical issue. In this study, we show that the IVC order gives rise to anomalous valley-current generation driven by surface acoustic waves (SAWs). The anomalous valley current exhibits a characteristic power-law dependence for low-frequency SAWs. Furthermore, we demonstrate by numerical analysis that the IVC order significantly enhances valley-current generation in rhombohedral graphene. These results open a pathway toward exploring exotic phenomena emerging from valley-gauge-symmetry breaking, in close analogy with gauge-symmetry breaking in superconductors.