Hysteretic responses of nanomechanical resonators based on crumpled few-layer graphene

TL;DR

This study investigates the hysteretic mechanical responses of crumpled few-layer graphene membranes in nanomechanical resonators, revealing shape-dependent nonlinearities and the effects of annealing on restoring regular behavior.

Contribution

It demonstrates hysteretic responses in crumpled graphene resonators and links these to morphology and adsorbates, offering insights into their nonlinear mechanical behavior.

Findings

Hysteresis observed in static and dynamic responses with increasing and decreasing gate voltage.

Discontinuities indicate sudden shape and strain changes in membranes.

Annealing removes hysteresis, restoring regular responses.

Abstract

Manipulating two-dimensional materials occasionally results in crumpled membranes. Their complicated morphologies feature an abundance of folds, creases and wrinkles that make each crumpled membrane unique. Here, we prepare four nanomechanical resonators based on crumpled membranes of few-layer graphene and measure their static response and the spectrum of their dynamic response. We tune both responses with a dc voltage applied between the membrane and an underlying gate electrode. Surprisingly, we find that all four resonators exhibit hysteretic responses as the gate voltage is increased and then decreased. Concomitant discontinuities in the static response and in the vibrational resonant frequencies indicate a sudden change in the shape and in the tensile strain of the membranes. We also find that the hystereses can be removed and regular responses can be restored by annealing the resonators. We hypothesize that the hysteretic nature of the responses may originate from an interplay between the rugged morphology of the membranes and adsorbates trapped within the confine of the folds.