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.
报告摘要
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.