Anisotropic in-plane thermal conductivity observed in multilayer silicene

@Authour Yang Zhou

@Mail y_zhou13@fudan.edu.cn

@Fudan University Computational Condensed Matter Group(CCMG)

Abstract

By means of Boltzmann Transportation Equation (BTE), we systematically study the thermal transportation properties of different types of multilayer silicene. It is found that the thermal transport properties of multilayer silicene structures have significant surface effect and size effect in interlayer direction. Surface reconstruction affects heat transport very well , the thermal conductivity of bilayer silicene with different reconstruction can reach up to $57.9 W/mK$, and can be as low as $3.31 W/mK$ and the anisotropy can be as high as $41.1%$.With the increase of the number of layers, the thermal conductivity of the zigzag direction decreases significantly, but the thermal conductivity increases a little in the armchair direction, and the anisotropy of thermal conductivity decreased which is due to the smaller affection of surface reconstruction. Phonon lifetime and group velocity play differenct roles in bilayer structures and 3-8 layer structures where the anisotropy of the former is mainly effected by the anisotropy of lifetime but that of the later is the result of anisotropy of group velocity. This work could be helpful in the field of heat management, thermoelectric applications involving silicene and other multilayer nano materials in the future.

Keywords:Thermal conductivity, multilayer silicene, surface reconstruction, anisotropy