Artificial Crystal Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences
Dynamics of Domains and Domain Walls in Ferroelectrics: from multistate memory to tunable low-loss microwave devices
Speaker: Dr. Shi Liu（刘仕）
School of Science, Westlake University（西湖大学理学院）
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.
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.
刘仕2009年本科毕业于中国科学技术大学化学物理系，2015年博士毕业于美国宾夕法尼亚大学化学系。先后师从铁电领域著名理论物理学家Andrew M. Rappe和Ronald E. Cohen。博士毕业后获得卡内基博士后奖学金，于2015年9月-2018年1月任职于华盛顿卡内基科学研究所。2018年2月获得美国陆军研究所优秀博士后奖学金，在美国陆军研究所继续开展博士后研究工作。主要从事凝聚态功能材料、能源材料、多尺度/跨尺度计算物理方法开发等方面的研究。2017年获的美国物理学会计算物理领域Nicholas Metropolis Award。 2019年6月全职加入西湖大学。自2013年起，在一流学术杂志发表论文共39篇，包括3篇Nature，2篇Phys. Rev. Lett.，1篇 Nature Mater.，2篇Nature Communications等。