FPU physics with nanomechanical graphene resonators: intrinsic relaxation and thermalization from flexural mode coupling

TL;DR

This paper demonstrates that nonlinear mode coupling in nanomechanical graphene resonators causes intrinsic thermalization, which limits their quality factor and provides a platform to study FPU physics through molecular dynamics and continuum models.

Contribution

It reveals the intrinsic thermalization mechanism in graphene resonators due to nonlinear mode coupling, linking it to FPU physics and quantifying the thermalization rate.

Findings

Thermalization rate is independent of resonator radius.

Thermalization rate scales as temperature over prestrain squared.

Nanomechanical graphene drums can serve as test beds for FPU physics.

Abstract

Thermalization in nonlinear systems is a central concept in statistical mechanics and has been extensively studied theoretically since the seminal work of Fermi, Pasta and Ulam (FPU). Using molecular dynamics and continuum modeling of a ring-down setup, we show that thermalization due to nonlinear mode coupling intrinsically limits the quality factor of nanomechanical graphene drums and turns them into potential test beds for FPU physics. We find the thermalization rate $\Gamma$ to be independent of radius and scaling as $\Gamma\sim T^*/\epsilon_{{\rm pre}}^2$, where $T^*$ and $\epsilon_{{\rm pre}}$ are effective resonator temperature and prestrain.