Strong phase correlation between diffusons governs heat conduction in amorphous silicon

TL;DR

This paper reveals that strong phase correlation between diffusons, a type of vibrational mode, governs heat conduction in amorphous silicon, providing new insights into thermal transport mechanisms.

Contribution

It demonstrates that phase correlation between diffusons triggers heat conduction, offering a new framework for understanding thermal transport in amorphous materials.

Findings

Diffusons exhibit wave-like behavior influencing heat transfer.

Phase correlation between modes is crucial for thermal conduction.

Temperature and length dependence of thermal conductivity are explained.

Abstract

Understanding the thermal vibrations and thermal transport in amorphous materials is an important but long-standing issue in several theoretical and practical fields. Using direct molecular dynamic simulations, we demonstrate that the strong phase correlation between local and non-propagating modes, commonly named diffusons in the terminology of amorphous systems, triggers conduction of heat. By considering the predominance of collective excitations in amorphous silicon, the predominant contribution of diffusons, due to phase correlation, is predicted, which further reveals the unique temperature and length dependences of thermal conductivity in amorphous silicon. The explored wavelike behavior of diffusons uncovers the unsolved physical picture of mode correlation in prevailing models and further provides an interpretation of their ability to transport heat. This work introduces a framework for understanding thermal vibrations and thermal transport in amorphous materials, as well as perspectives on the wave nature of thermal vibrations.