Mode coupling, bi-stability, and spectral broadening in buckled nanotube resonators

TL;DR

This paper introduces a novel buckled carbon nanotube resonator with bi-stability and high frequency tunability, providing insights into nonlinear mode coupling and dissipation mechanisms at the nanoscale.

Contribution

It demonstrates the first bi-stable CNT resonator with Euler-Bernoulli bi-stability and analyzes nonlinear mode coupling and dissipation mechanisms through 3D theoretical modeling.

Findings

Record electrical frequency tunability in CNT resonators.

Identification of Euler-Bernoulli bi-stability in larger buckled CNTs.

Explanation of low quality factors via nonlinear mode coupling.

Abstract

Bi-stable mechanical resonators play a significant role in various applications, such as sensors, memory elements, and quantum computing. While carbon nanotube (CNT) based resonators have been widely investigated as promising nano electro-mechanical devices, a bi-stable CNT resonator has never been demonstrated. Here, we report a new class of CNT resonators in which the nanotube is buckled upward. We show that a small upward buckling yields record electrical frequency tunability, whereas larger buckling can achieve Euler-Bernoulli (EB) bi-stability, the smallest mechanical resonator with two stable configurations to date. We believe that these recently discovered CNT devices will open new avenues for realizing nano-sensors, mechanical memory elements and parametric amplifiers. Furthermore, we present a three-dimensional theoretical analysis revealing significant nonlinear coupling between the in-plane and out-of-plane static and dynamic modes of motion, and a unique three-dimensional EB snap-through transition. We utilize this coupling to provide a conclusive explanation for the low quality factor in CNT resonators at room temperature, key in understanding dissipation mechanisms at the nano scale.