Energy transport in jammed sphere packings

Area of Science:

• Physics
• Materials Science
• Condensed Matter Physics

Background:

• Understanding energy transport in disordered materials like glasses is crucial.
• The boson peak in glasses is linked to vibrational anomalies and energy transport.
• The Ioffe-Regel criterion describes a crossover in wave transport.

Purpose of the Study:

• To investigate energy diffusivity in jammed sphere packings.
• To identify spectral measures of transport related to vibrational modes.
• To explore the connection between jamming and vibrational properties relevant to glasses.

Main Methods:

• Calculation of normal modes of vibration in jammed sphere packings.
• Determination of energy diffusivity as a spectral measure of transport.
• Analysis of the Ioffe-Regel crossover at the boson peak frequency.

Main Results:

• An Ioffe-Regel crossover in energy diffusivity was observed at the boson peak frequency.
• Diffusivity transitions from frequency-dependent to frequency-independent behavior.
• The crossover frequency shifts to zero as the system approaches the jamming transition.

Conclusions:

• Jamming transition properties directly influence a regime of nearly constant diffusivity.
• This regime, previously postulated for glasses, arises from jamming-related vibrational properties.
• The findings provide evidence for the role of jamming in glass dynamics and thermal conductivity.