Symmetry-breaking induced frequency combs in graphene resonators

TL;DR

This paper demonstrates how symmetry-breaking forces in graphene resonators can induce nonlinear phenomena, including frequency combs and chaotic dynamics, by tuning into internal resonances and exploiting non-symmetric restoring potentials.

Contribution

It introduces a method to generate mechanical frequency combs in graphene resonators through electrostatic symmetry-breaking and internal resonance tuning.

Findings

Frequency combs emerge near internal resonances in graphene resonators.

Symmetry-breaking induces a Neimark bifurcation leading to complex dynamics.

Strong mode coupling is achieved via electrostatic tuning.

Abstract

Nonlinearities are inherent to the dynamics of two-dimensional materials. Phenomena like intermodal coupling already arise at amplitudes of only a few nanometers, and a range of unexplored effects still awaits to be harnessed. Here, we demonstrate a route for generating mechanical frequency combs in graphene resonators undergoing symmetry-breaking forces. We use electrostatic force to break the membrane's out-of-plane symmetry and tune its resonance frequency towards a two-to-one internal resonance, thus achieving strong coupling between two of its mechanical modes. When increasing the drive level, we observe splitting of the fundamental resonance peak, followed by the emergence of a frequency comb regime. We attribute the observed physics to a non-symmetric restoring potential, and show that the frequency comb regime is mediated by a Neimark bifurcation of the periodic solution. These results demonstrate that mechanical frequency combs and chaotic dynamics in 2D material resonators can emerge near internal resonances due to symmetry-breaking.