# Giant Tunable Mechanical Nonlinearity in Graphene-Silicon Nitride Hybrid Resonator

## TL;DR

This paper demonstrates a hybrid graphene-silicon nitride resonator system where large, tunable mechanical nonlinearity is achieved, enabling novel phononic frequency combs and advancing control over mechanical resonator nonlinearities.

## Contribution

It introduces a hybrid platform combining SiNx and graphene resonators to induce and control giant mechanical nonlinearity, including the observation of a new phononic frequency comb.

## Key findings

- Induced large nonlinear response on SiNx resonator via coupling with graphene.
- Achieved tunable nonlinearity controlled by gate voltage.
- Observed a novel phononic frequency comb.

## Abstract

High quality factor mechanical resonators have shown great promise in developing classical or quantum technologies. Simultaneously, progress has been made in developing controlled mechanical nonlinearity. Here we combine these two directions of progress in a single platform consisting of coupled Silicon Nitride (SiNx) and graphene mechanical resonators. We show that nonlinear response can be induced on a large area SiNx resonator mode and can be efficiently controlled by coupling it to a gate-tunable, freely suspended graphene mode. The induced nonlinear response of the hybrid modes, as measured on the SiNx resonator surface is giant, with one of the highest measured Duffing constants. We observe a novel phononic frequency comb which we use as an alternate validation of the measured values, along with numerical simulations which are in overall agreement with measurements.