# Intrinsic dissipation mechanisms in metallic glass resonators

## TL;DR

This study uses molecular dynamics simulations to investigate intrinsic energy dissipation in metallic glass resonators, identifying key parameters like kinetic energy and system size that influence the quality factor and performance limits.

## Contribution

It introduces a detailed analysis of the intrinsic dissipation mechanisms in metallic glasses, highlighting the critical energy and strain thresholds affecting resonator quality factors.

## Key findings

- Atomic rearrangements occur above a critical kinetic energy $K_r$
- $K_r$ decreases with system size as a power-law, $K_r \\sim N^{-k}$
- Below a critical strain, large $Q$-values are achievable in metallic glass resonators.

## Abstract

Micro- and nano-resonators have important applications including sensing, navigation, and biochemical detection. Their performance is quantified using the quality factor $Q$, which gives the ratio of the energy stored to the energy dissipated per cycle. Metallic glasses are a promising materials class for micro- and nano-scale resonators since they are amorphous and can be fabricated precisely into complex shapes on these lengthscales. To understand the intrinsic dissipation mechanisms that ultimately limit large $Q$-values in metallic glasses, we perform molecular dynamics simulations to model metallic glass resonators subjected to bending vibrations. We calculate the vibrational density of states, redistribution of energy from the fundamental mode of vibration, and $Q$ versus the kinetic energy per atom $K$ of the excitation. In the linear and nonlinear response regimes where there are no atomic rearrangements, we find that $Q \rightarrow \infty$ (since we do not consider coupling to the environment). We identify a characteristic $K_r$ above which atomic rearrangements occur, and there is significant energy leakage from the fundamental mode to higher frequencies, causing finite $Q$. Thus, $K_r$ is a critical parameter determining resonator performance. We show that $K_r$ decreases as a power-law, $K_r\sim N^{-k},$ with increasing system size $N$, where $k \approx 1.3$. We estimate the critical strain $\langle \gamma_r \rangle \sim 10^{-8}$ for micron-sized resonators below which atomic rearrangements do not occur, and thus large $Q$-values can be obtained when they are operated below $\gamma_r$. We find that $K_r$ for amorphous resonators is comparable to that for resonators with crystalline order.