Sound attenuation in finite-temperature stable glasses.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Amorphous Solids

Background:

• Thermal conductivity in amorphous solids differs from crystalline solids, exhibiting universal behavior.
• Sound attenuation is linked to this universal behavior, with prior simulations showing Rayleigh and quadratic scaling.
• Anharmonic effects at finite temperatures complicate understanding sound attenuation in glasses.

Purpose of the Study:

• Investigate sound attenuation at finite temperatures in model glasses of varying stability.
• Identify new scaling laws governing sound attenuation based on temperature and glass stability.
• Reconcile discrepancies between simulations, theory, and experiments regarding sound attenuation in glasses.

Main Methods:

• Utilized computer simulations to study model glasses.
• Examined glasses ranging from unstable (aging) to experimentally relevant stability.
• Analyzed sound attenuation (Γ) as a function of wavevector (k) at finite temperatures.

Main Results:

• Observed unchanged quadratic scaling at large wavevectors across all temperatures.
• Found distinct small wavevector scaling: Γ~k^1.5 for aging glasses and Γ~k^2 for non-aging glasses.
• Identified crossovers in stable glasses: Γ~k^2 to Γ~k^4 (Rayleigh) to Γ~k^2 at large wavevectors.

Conclusions:

• Established new temperature- and stability-dependent scaling laws for sound attenuation in glasses.
• Demonstrated that quadratic scaling at large wavevectors is temperature-independent.
• Provided a computational basis for understanding the temperature dependence of thermal conductivity in amorphous solids.