Anomalous phonon scattering and elastic correlations in amorphous solids

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Physics

Background:

• Glasses display distinct low-temperature thermal and vibrational properties compared to crystals.
• The damping of long-wavelength phonons in glasses is significantly higher than in crystals, but the underlying mechanism related to structural disorder is not fully understood.

Purpose of the Study:

• To investigate the impact of atomic-scale structural disorder on macroscopic phonon damping in glasses.
• To elucidate the relationship between spatial correlations of elastic disorder and phonon scattering mechanisms in amorphous solids.

Main Methods:

• Theoretical analysis of phonon damping in disordered materials.
• Modeling acoustic phonon scattering by local elastic heterogeneities.
• Investigating the role of spatial correlations in elastic disorder and stress correlations.

Main Results:

• Phonon damping in glasses scales as k^d+1ln(k), deviating from the predicted Rayleigh scattering (k^d+1).
• This enhanced damping is attributed to long-range spatial correlations of elastic disorder, driven by stress correlations.
• The findings suggest a key difference in the nature of disorder between amorphous solids and crystals.

Conclusions:

• Long-range spatial correlations of local stress and elasticity are crucial features distinguishing amorphous solids from crystals.
• The observed phonon damping mechanism provides insight into the unique properties of glasses at low temperatures.
• Structural disorder, particularly its spatial correlation, fundamentally influences the vibrational dynamics of amorphous materials.