报告题目：Ferroelectric switching and ultrafast simulations
主持人（邀请人）： 张立军 教授
摘要：Ultrafast light-matter interactions present a promising route to control ferroelectric polarization. One emergent light-induced technique for controlling polarization consists in anharmonically driving another high-frequency phonon mode. A step towards such technique has been recently accomplished in the experiment (Phys. Rev. Lett. 118, 197601), but the polarization was reported to be only partially reversed and for a short lapse of time. It is presently unclear if a full control of a polarization can be achieved by activating such high-frequency phonon mode via terahertz pulse stimuli. In this talk, a realistic model on the prototypical ferroelectric KNbO3 will be introduced, which not only allows us to reproduce a polarization transient partial reversal analogous to the experiment, but also uncovers other light-driven effects. In particular, it further reveals and explains (1) how a full reversal can indeed happen in some cases; and (2) also predict a variety of other light-induced polarization reorientations as a result of a mechanism we coin as “squeezing” effect. Such “squeezing” mechanism further allows us to design a strategy for an ultrafast deterministic control of the polarization. In the end, I will introduce our code LINVARIANT that is used for this light-matter simulation project. LINVARIANT is a first-principle based multi-physics and multi-scale simulation toolkit that is capable to construct effective Hamiltonian for ferroelectric, magnetic, and electronic materials and solve them in large scale at finite temperature.
Dr. Peng Chen obtained his Ph.D. in Theoretical Physics from the Institute of Physics, Chinese Academy of Sciences (China). He is currently a postdoc researcher at the Department of Physics, University of Arkansas (US). He was a Research Associate at the Italian Institute of Technology (Italy) and a visiting scholar at the Luxembourg Institute of Science and Technology (Luxembourg). He has published as the first/co-first and corresponding author high-impact journals including Nature materials (1), Physics Review Letter (1), Advanced Materials (1), and Physics Review B (3). His main research interests focus on the couplings of different ferroic orders and light-matter interactions in materials at multiscale levels.