Dimer rattling mode induced low thermal conductivity in an excellent acoustic conductor
Abstract
A solid with larger sound speeds exhibits higher lattice thermal conductivity (k_{lat}). Diamond is a prominent instance where its mean sound speed is 14400 m s-1 and k_{lat} is 2300 W m-1 K-1. Here, we report an extreme exception that CuP2 has quite large mean sound speeds of 4155 m s-1, comparable to GaAs, but the single crystals show a very low lattice thermal conductivity of about 4 W m-1 K-1 at room temperature, one order of magnitude smaller than GaAs. To understand such a puzzling thermal transport behavior, we have thoroughly investigated the atomic structure and lattice dynamics by combining neutron scattering techniques with first-principles simulations. Cu atoms form dimers sandwiched in between the layered P atomic networks and the dimers vibrate as a rattling mode with frequency around 11 meV. This mode is manifested to be remarkably anharmonic and strongly scatters acoustic phonons to achieve the low k_{lat}. Such a dimer rattling behavior in layered structures might offer an unprecedented strategy for suppressing thermal conduction without involving atomic disorder.
Keywords
Cite
@article{arxiv.2006.00649,
title = {Dimer rattling mode induced low thermal conductivity in an excellent acoustic conductor},
author = {Ji Qi and Baojuan Dong and Zhe Zhang and Zhao Zhang and Yanna Chen and Qiang Zhang and Sergey Danilkin and Xi Chen and Liangwei Fu and Xiaoming Jiang and Guozhi Chai and Satoshi Hiroi and Koji Ohara and Zongteng Zhang and Weijun Ren and Teng Yang and Jianshi Zhou and Sakata Osami and Jiaqing He and Dehong Yu and Bing Li and Zhidong Zhang},
journal= {arXiv preprint arXiv:2006.00649},
year = {2020}
}
Comments
four figures and one table in the main text