Department of Physics, The Chinese University of Hong Kong (香港中文大学物理系)

报告摘要:

Moiré superlattices, created by combining low-dimensional materials with small lattice mismatches or different orientations, offer a powerful platform for exploring fascinating physical phenomena. Recent advances in optical spectroscopies have revealed rich experimental signatures of novel moiré exciton states in 2D superlattices; however, the microscopic nature of these states and strategies for their effective manipulation remain to be fully explored. In this talk, I will introduce our recent discoveries in 2D moiré-induced exciton physics based on newly-developed time-dependent interacting Green’s function approach and the Bethe-Salpeter Equation method. First, I will demonstrate that moiré excitonic effects can greatly enhance nonlinear optical responses, leading to the striking formation of light-induced nonlinear photocurrent vortex crystals—2D arrays of moiré-scale current vortices and associated magnetic fields. This provides a promising all-optical control route to manipulate such exotic photoexcited moiré quantum matter. Second, I will show that the moiré potential can be continuously and efficiently tuned via pressure engineering, driving exciton physics from the weak- to the strong-moiré regime. In this process, we identify a previously underexplored moiré exciton state arising from the coupling between intrinsic excitonic Coulomb attraction and external moiré confinement. Our results highlight the rich photophysics of 2D moiré superlattices and open new opportunities for applications in moiré-based optoelectronics and photovoltaics.

报告人简介:

Chen Hu (胡晨) is an Assistant Professor in the Department of Physics at the Chinese University of Hong Kong. He was a postdoctoral research fellow at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory from 2021 to 2024. He earned his PhD in physics from McGill University in Canada in 2020. His research engages in the fields of theoretical condensed matter physics and computational material science, with the primary aim of exploring novel quantum material physics through advanced first-principles theoretical methodologies and computational tools. He focuses on intriguing photoexcited phenomena, moiré physics, ultrafast and nonlinear optoelectronics, topological matter, quantum transport and spintronics in emerging low-dimensional quantum materials and nanodevices.

邀请人：许杨特聘研究员

联系方式：82648119