报告题目：Dynamics of Domains and Domain Walls in Ferroelectrics: 

                    from multistate memory to  tunable low-loss microwave devices

报告人：刘仕 特聘研究员  

                西湖大学理学院

报告时间：2019年8月19日(星期一) 10:00

报告地点：理化大楼6007室

Abstract: 

Ferroelectrics, a major class of high-coupling materials characterized by the switchable polarization, have become important in modern devices ranging from medical ultrasound, non-volatile memory to vibration-powered electronics. The device functionalities heavily rely on the interactions between the electric polarization and applied stimuli (e.g., electric fields). Understanding the dynamics of ferroelectric domains and domain walls in response to external perturbations is important for the development of ferroelectric-based functional devices. In this talk, I will first introduce a classical force field we developed based on the bond valence theory which enabled large-scale molecular dynamics simulations of typical ferroelectric materials at the million-atom scale. I will then explain a theory-experiment collaboration wherein we demonstrated deterministic and repeatedly obtainable multistate polarizations in ferroelectric thin films, highlighting the potential of ferroelectrics for adaptive neuromorphic electronics. Finally, I will explain how the resonance of domain walls can be exploited to obtain tunable dielectrics with ultralow loss and high tunability.

Brief CV:

Shi Liu graduated in 2009 with a B.S. in Chemical Physics from the University of Science and Technology of China, before completing his Ph.D. from the Chemistry Department at the University of Pennsylvania in 2015. During the Ph.D. program, he worked under the direction of Professor Andrew M. Rappe, mainly focusing on computational condensed matter physics. Following completion of his Ph.D., Dr. Liu was offered a Carnegie Fellowship at the Carnegie Institution for Science in Washington, D.C., where he worked with Dr. Ronald E. Cohen on multiscale simulations of defects in ferroelectrics and hybrid perovskites for photovoltaic applications. He received the American Physical Society Nicholas Metropolis Award in Computational Physics in 2017 and SEDD (Sensors and Electronic Device Directorate) Distinguished Fellowship at U.S. Army Research Laboratory in 2018. In June 2019, Dr. Liu joined the School of Science at Westlake University.