报告人：孟胜

报告题目：Optical control of multi-stage phase transitions in condensed matters

报告摘要：The temporal characters of laser-driven phase transitions have been investigated using time-dependent first principles simulations in prototype materials including MoTe2, VO2 and liquid water. The process is found to be induced by fundamental electron-phonon interactions, with an unexpected phonon excitation and coupling pathway closely related to the nonequilibrium relaxation of photoexcited electrons. The order-to-order phase transformation is dissected into three substages, involving energy and momentum scattering processes from optical to acoustic phonon modes in sub-picosecond timescale. Intermediate states along the nonadiabatic transition pathway is also identified. These results have profound implications on nonequilibrium phase engineering.

报告简介：Dr. Sheng Meng is a professor and head of the Surface Quantum Dynamics group at Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences since 2009. He obtained his Bachelor degree in physics from University of Science and Technology of China (USTC) in 2000, and Ph.D. degree in condensed matter physics from Institute of Physics, Chinese Academy of Sciences and applied physics from Chalmers University of Technology, Sweden in 2004. During 2005-2009, he worked at Harvard University’s Department of Physics first as a post-doctoral researcher then a research associate. Dr. Meng’s research interests focus on quantum electron dynamics in condensed matter; design of quantum materials; and electronic/quantum origin of wetting. He has published ~200 technical papers in peer-reviewed journals, and has received 10000+ citations with a H-index 55.