Effect of structural defects on anomalous ultrasound propagation in solids during second-order phase transitions

TL;DR

This study investigates how structural defects influence ultrasound attenuation and velocity dispersion during phase transitions in solids, revealing that defects amplify these effects near the critical temperature.

Contribution

It provides a field-theoretical analysis of acoustic wave behavior in disordered solids during phase transitions, including fluctuation and relaxation mechanisms, with new calculations for disordered systems.

Findings

Structural defects increase ultrasound attenuation near critical temperature.

Disordered systems show stronger temperature and frequency dependence of acoustic properties.

Asymptotic behavior of attenuation and dispersion functions is characterized in different regions.

Abstract

The effect of structural defects on the critical ultrasound attenuation and ultrasound velocity dispersion in Ising-like three-dimensional systems is studied. A field-theoretical description of the dynamic effects of acoustic-wave propagation in solids during phase transitions is performed with allowance for both fluctuation and relaxation attenuation mechanisms. The temperature and frequency dependences of the scaling functions of the attenuation coefficient and the ultrasound velocity dispersion are calculated in a two-loop approximation for pure and structurally disordered systems, and their asymptotic behavior in hydrodynamic and critical regions is separated. As compared to a pure system, the presence of structural defects in it is shown to cause a stronger increase in the sound attenuation coefficient and the sound velocity dispersion even in the hydrodynamic region as the critical temperature is reached. As compared to pure analogs, structurally disordered systems should exhibit stronger temperature and frequency dependences of the acoustic characteristics in the critical region.