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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 acoustoelectric current reveals 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. 1 arXiv:1911.10856v1 [cond-mat.mes-hall]

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An acoustoelectric current driven through a quantum point contact (QPC) on a suspended nanobridge by surface acoustic waves displays a non-trivial behavior in the presence of a perpendicular magnetic field. Our study reveals that the dependencies of this current on the QPC gate voltage and magnetic field can be explained by a variable material parameter r m. We develop a theoretical model for this phenomenon based on the modification of the Coulomb interaction and, correspondingly, the electron-SAWs coupling in the presence of the electron confinement.

Coupling graphene’s excellent electron and spin transport properties with a higher spin–orbit coupling (SOC) material allows tackling the hurdle of spin manipulation in graphene due to the proximity to van der Waals layers. Here, we use magneto-transport measurements to study the electron spin resonance on a combined system of graphene and MoS2 at 1.5 K. The electron spin resonance measurements are performed in the frequency range of 18–33 GHz, which allows us to determine the g-factor in the system. We measure the average g-factor of 1.91 for our hybrid system, which is a considerable shift compared to that observed in graphene on SiO2. This is a clear indication of proximity induced SOC in graphene in accordance with theoretical predictions.