Microscopic nanomechanical dissipation in gallium arsenide resonators

TL;DR

This study investigates nanomechanical dissipation in gallium arsenide resonators, revealing surface and microscopic effects, especially two-level systems, as key factors influencing damping across a wide temperature range.

Contribution

It provides a systematic analysis linking nanomechanical dissipation in gallium arsenide resonators to microscopic surface properties and two-level systems models.

Findings

Phonon-phonon interactions contribute to dissipation at room temperature.

Surface modifications alter the quality factor, highlighting surface dissipation.

Two-level systems models accurately fit the temperature dependence of dissipation.

Abstract

We report on a systematic study of nanomechanical dissipation in high-frequency (approximatively 300 MHz) gallium arsenide optomechanical disk resonators, in conditions where clamping and fluidic losses are negligible. Phonon-phonon interactions are shown to contribute with a loss background fading away at cryogenic temperatures (3 K). Atomic layer deposition of alumina at the surface modifies the quality factor of resonators, pointing towards the importance of surface dissipation. The temperature evolution is accurately fitted by two-level systems models, showing that nanomechanical dissipation in gallium arsenide resonators directly connects to their microscopic properties. Two-level systems, notably at surfaces, appear to rule the damping and fluctuations of such high-quality crystalline nanomechanical devices, at all temperatures from 3 to 300K.