Dynamic local strain in graphene generated by surface acoustic waves

TL;DR

This paper demonstrates that surface acoustic waves can dynamically modulate the optical phonon modes of graphene, leading to significant changes in Raman scattering intensity and phonon frequency, with potential applications in 2D material control.

Contribution

It introduces a method to control graphene's vibrational properties using high-frequency surface acoustic waves, a novel approach for dynamic strain engineering in 2D materials.

Findings

Raman scattering intensity varies by up to 15% due to SAW-induced strain.

Phonon frequency shifts by up to 10 cm$^{-1}$ in graphene under SAW.

Effective hydrostatic strain of 0.24% achieved in the experiment.

Abstract

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 a single layer graphene atop a LiNbO$_{3}$ piezoelectric substrate with a SAW resonator operating at a frequency of $ \sim $ 400 MHz. Thus, we demonstrate that SAWs are powerful tools to modulate 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.