Dynamic Local Strain in Graphene Generated by Surface Acoustic Waves

We experimentally demonstrate that the Raman-active optical phonon modes of single-layer graphene can be modulated by the dynamic local strain created by surface acoustic waves (SAWs). In particular, the dynamic strain field of the SAW is shown to induce a Raman scattering intensity variation as large as 15% and a phonon frequency shift of up to 10 cm^-1 for the G band, for instance, for an effective hydrostatic strain of 0.24% generated in single-layer graphene atop a LiNbO₃ piezoelectric substrate with a SAW resonator operating at a frequency of ∼400 MHz. Thus, we demonstrate that SAWs are powerful tools for modulating the optical and vibrational properties of supported graphene by means of the high-frequency localized deformations tailored by the acoustic transducers, which can also be extended to other 2D systems.