Mode-Dependent Scaling of Nonlinearity and Linear Dynamic Range in a NEMS Resonator

TL;DR

This study investigates how nonlinearity and linear dynamic range scale with eigenmode number in NEMS resonators, revealing mode-dependent behaviors that can enhance sensing capabilities.

Contribution

It provides experimental and theoretical analysis of mode-dependent nonlinearity scaling laws in NEMS resonators up to the 11th eigenmode.

Findings

Duffing constant scales as n^4

Critical amplitude decreases as 1/n

Linear dynamic range increases weakly with mode number

Abstract

Even a relatively weak drive force is enough to push a typical nanomechanical resonator into the nonlinear regime. Consequently, nonlinearities are widespread in nanomechanics and determine the critical characteristics of nanoelectromechanical systems (NEMS) resonators. A thorough understanding of the nonlinear dynamics of higher eigenmodes of NEMS resonators would be beneficial for progress, given their use in applications and fundamental studies. Here, we characterize the nonlinearity and the linear dynamic range (LDR) of each eigenmode of two nanomechanical beam resonators with different intrinsic tension values up to eigenmode $n=11$. We find that the modal Duffing constant increases as $n^4$, while the critical amplitude for the onset of nonlinearity decreases as $1/n$. The LDR, determined from the ratio of the critical amplitude to the thermal noise amplitude, increases weakly with $n$. Our findings are consistent with our theory treating the beam as a string, with the nonlinearity emerging from stretching at high amplitudes. These scaling laws, observed in experiments and validated theoretically, can be leveraged for pushing the limits of NEMS-based sensing even further.