In silico broadband mechanical spectroscopy of amorphous tantala

Abstract

Adopting an agnostic approach, the quality factor Q of tantala glass is drawn via in silico mechanical spectroscopy in wide ranges of temperature (10-300 K) and frequency (500MHz≤f≤1THz). At the highest frequencies, Qf-3, consistent with Rayleigh sound scattering. For frequencies lower than terahertz, losses exhibit a weak power-law frequency dependence Qf-α with α∼0.1to0.2, depending on glass preparation and temperature. Arguing the validity of the power law down to 1 kHz, we show striking agreement with the losses measured in annealed amorphous films in the whole temperature range, revealing similitude between disordered structures created by different routes (quench cooling and deposition). Our results do not support the scenario of the mechanical loss due to activated relaxation of independent two-level systems.