Low-frequency non-phononic vibrations of amorphous solids

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Amorphous solids possess anomalous low-temperature mechanical and thermodynamic properties distinct from crystalline solids.
• Understanding these low-temperature anomalies is crucial but remains a significant scientific challenge.
• Low-frequency vibrations are recognized as key to explaining these properties in amorphous materials.

Purpose of the Study:

• To review recent advancements in the investigation of low-frequency vibrations in amorphous solids.
• To focus on the low-frequency non-phononic spectrum and its implications.
• To discuss the role of these vibrations in phenomena like the glass transition and phonon attenuation.

Main Methods:

• Focus on numerical and theoretical investigations of the low-frequency non-phononic spectrum.
• Analysis of recent advancements in experimental and computational techniques.
• Review of literature concerning vibrational properties and their relation to material characteristics.

Main Results:

• A surge in numerical and theoretical studies of the low-frequency non-phononic spectrum beyond the Debye model.
• Identification of unresolved issues and ongoing debates in the field.
• Insights into the connection between low-frequency non-phononic vibrations and phenomena such as the glass transition, phonon attenuation, two-level systems, and soft spots.

Conclusions:

• Low-frequency non-phononic vibrations are critical for understanding amorphous solid behavior at low temperatures.
• Despite progress, the low-frequency non-phononic spectrum presents persistent challenges and areas for future research.
• Further investigation into these vibrations offers pathways to comprehending complex phenomena in disordered materials.