Evidence of universality in the dynamical response of micromechanical diamond resonators at millikelvin temperatures

TL;DR

This study investigates the low-temperature dissipation and frequency shift in diamond micromechanical resonators, revealing universal behavior similar to other materials and supporting the glass model of tunneling two-level systems.

Contribution

It provides the first evidence of universal dynamical response in diamond resonators at millikelvin temperatures, aligning with predictions from the glass model.

Findings

Frequency shift follows a logarithmic temperature dependence.

Dissipation scales as T^{1/3} and saturates at low temperatures.

Universal behavior observed across diamond, silicon, and gallium arsenide resonators.

Abstract

We report kelvin to millikelvin-temperature measurements of dissipation and frequency shift in megahertz-range resonators fabricated from ultra-nanocrystalline diamond. Frequency shift $\delta f/f_0$ and dissipation $Q^{-1}$ demonstrate temperature dependence in the millikelvin range similar to that predicted by the glass model of tunneling two level systems. The logarithmic temperature dependence of $\delta f/ f_0$ is in good agreement with such models, which include phonon relaxation and phonon resonant absorption. Dissipation shows a weak power law, $Q^{-1}\propto T^{{1/3}}$, followed by saturation at low temperature. A comparison of both the scaled frequency shift and dissipation in equivalent micromechanical structures made of single-crystal silicon and gallium arsenide indicates universality in the dynamical response.