Acoustically driven Dirac electrons in monolayer graphene

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 (IDT) 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 surface acoustic wave (SAW) velocity depending on the conductivity of the graphene layer. The acousto-electric current reveals an additional fine structure that is absent in pure magneto-transport. 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.