报告题目：Phonon Transport in Silicon Nanowires:Application of Real Space Kubo Method for Few Million Atoms

报告人：李武 研究员（深圳大学高等研究院）

报告时间：2018年9月10日（星期一）上午10:00

报告地点：物理学院新楼5楼多功能报告厅

报告摘要：

Due to orders of magnitude reduction of thermal conductivity, silicon nanowires have been found to be good thermoelectrics. Despite tremendous studies, a satisfactory understanding of the ultralow thermal conductivity is still lacking. We have employed a real space Kubo method to directly simulate phonon transport in silicon nanowires with few million atoms [1]. We found that in nanowires with diameter R surface-roughness-limited diffusivity or mean free path follows R2 dependence, in striking contrast to the classical Casimir’s linear R dependence. The diffusivity is linked to the change of the number of atoms due to roughness. We also observed significant reduction of phonon group velocity, which can persist in several hundreds of nanometers thick Si nanowires. Moreover, our atomistic simulation directly shows that the Casimir's limit can underestimate the surface scattering by more than one order of magnitude in nanostructures. We further employed Boltzmann transport equation to investigate the anharmonic phonon scattering [2], which is found to be enhanced in nanowires, also accounting for the reduction of thermal conductivity.

Refs:

[1] Liyan Zhu, Baowen Li, Wu Li, Phys. Rev. B 94, 115420(2016)

[2] Zahid Rashid, Liyan Zhu, Wu Li Phys. Rev. B 97, 075441(2018)

报告人简介：

李武，深圳大学高等研究院研究员。2011年于中国科学院物理研究所获得博士学位，博士期间（2008-2010）获中国科学院-马普学会联合培养博士生奖学金，于德国德累斯顿工业大学（TU Dresden）学习。2011-2013年在法国原子能与替代能源委员会（CEA）从事博士后研究，2013-2015年作为玛丽居里学者在荷兰科学计算与模拟公司从事博士后研究，2015年在CEA任研发工程师。李武博士主要从事材料输运性质的理论计算研究，是科学计算开源软件ShengBTE主要开发者。其在PRB, PRL, PRX等期刊发表论文30余篇，论文总引用1400余次。

邀请人：余睿教授