IMSE Seminar with Nonlinear Light-Matter Interaction in 2D Quantum Materials
The ability to achieve noninvasive detection and efficient control of electric and magnetic orders as well as topology in 2D quantum materials is of great importance to the development of ultrathin quantum devices. In this talk, I will present our recent theoretical effort on understanding and predicting the nonlinear response, sensing, and control in 2D quantum materials. First, I will present our theoretical study on second harmonic generation (SHG) in semiconducting 2D materials and discuss the microscopic origin of the large SHG responses in monolayer group IV monochalcogenides as well as recent experiment progress. In the second part of the talk, I will discuss sliding ferroelectricity in time-reversal invariant few-layer WTe2. Although semimetallic it holds out-of-plane polarization which can be switched via interlayer sliding under vertical electric field. Moreover, ferroelectric nonlinear Hall effect can be achieved in few-layer WTe2 by utilizing the intrinsic coupling among nonlinear susceptibility, crystalline symmetry, and quantum geometry of electronic states, paving a theoretical foundation for nonlinear quantum memory such as Berry curvature memory. Recent experimental demonstration of ferroelectric nonlinear anomalous Hall effect and Berry curvature memory in few-layer WTe2 will also be discussed. Finally, I will present our recent study of nonlinear photocurrent in РТ-symmetric magnetic topological quantum materials where nonlinear probe could be particularly fruitful for probing and understanding magnetic topological quantum materials.
Dr. Xiaofeng Qian is an Associate Professor in the Department of Materials Science and Engineering, affiliated with the Department of Physics and Astronomy and the Department of Electrical and Computer Engineering at Texas A&M University. He received his Ph.D. degree in Nuclear Science and Engineering at MIT in 2008. He then worked with Profs. Nicola Marzari and Ju Li as postdoc at MIT. In 2015, he joined Texas A&M University. Prof. Qian has published >80 journal articles and two patents, and received NSF CAREER award in 2018, Materials Today Rising Star Award in 2020, and TEES Young Faculty Fellow Award and AZZ Faculty Fellow in 2021. His research areas include first-principles electronic structure theory, nonlinear light-matter interaction, topological materials and topological phase transition, quantum transport, photovoltaics, strain engineering, and lowdimensional materials.
Faculty, students, and the general public are invited.