Acoustically driven Dirac electrons in monolayer graphene

TL;DR

This study explores how surface acoustic waves interact with Dirac electrons in monolayer graphene, revealing oscillatory velocity changes and fine structures in acousto-electric signals influenced by strain effects.

Contribution

It demonstrates the coupling between surface acoustic waves and Dirac electrons in graphene, showing new effects like velocity oscillations and strain-induced shifts.

Findings

Oscillatory attenuation of SAW velocity depending on graphene conductivity

Fine structure in acousto-electric current absent in pure magnetotransport

Shift in acousto-electric voltage attributed to strain effects on Dirac cone

Abstract

We demonstrate the interaction between surface acoustic waves and Dirac electrons in monolayer graphene at low temperatures and high magnetic fields. A metallic interdigitated transducer launches surface waves that propagate through a conventional piezoelectric GaAs substrate and couple to large-scale monolayer CVD graphene films resting on its surface. Based on the induced acousto-electric current, we characterize the frequency domains of the transducer from its first to the third harmonic. We find an oscillatory attenuation of the SAW velocity depending on the conductivity of the graphene layer. The acousto-electric current reveals additional fine structure that is absent in pure magnetotransport. In addition we find a shift between the acousto-electric longitudinal voltage and the velocity change of the SAW. We attribute this shift to the periodic strain field from the propagating SAW that slightly modifies the Dirac cone.