On 29 April, Professor Chen Jie's team at the Centre for Phononics in the School of Physical Sciences and Engineering and his collaborators published a research paper entitled "How coherence is governing diffuson heat transfer in amorphous solids" online in npj Computational Materials, developing an important theory to describe heat transport in amorphous materials.
Figure 1. (a) Atomic structure diagram of amorphous silicon. (b) Amorphous silicon thermal conductivity prediction based on coherent thermal transport theory and comparison with other results, where p(particle-like) is based on particle images and w(wave-like) is based on fluctuation images.
Thermal transport in amorphous materials has remained one of the fundamental questions in solid state physics while involving a very large field of applications. Using a heat conduction theory incorporating coherence, we demonstrate that the strong phase correlation between local and non-propagating modes, commonly named diffusons in the terminology of amorphous systems, triggers the conduction of heat. By treating the thermal vibrations as collective excitations, the significant contribution of diffusons, predominantly relying on coherence, further reveals interesting temperature and length dependences of thermal conductivity. The propagation length of diffuson clusters is found to reach the micron, overpassing the one of propagons. 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 transport in amorphous materials, as well as an unexpected insight into the wave nature of thermal vibrations.
npj Computational Materials is an English-language journal about computational physics and computational materials published by the Shanghai Institute of Ceramics, Chinese Academy of Sciences in collaboration with Nature Publishing Group, and was selected as one of the "Most Influential Chinese Academic Journals" in 2020. Dr. Zhongwei Zhang, a postdoctoral fellow at the University of Tokyo, is the first author of the paper, and Prof. Jie Chen and Prof. Sebastian Volz of CNRS are the co-corresponding authors. Dr. Zhongwei Zhang will soon join Prof. Jie Chen 's group as an Assistant Professor.
.This project is also supported in part by the grants from the National Natural Science Foundation of China, Science and Technology, and so on.
