5月16日 物理学院学术报告会（第25期）香港大学姚望教授学术报告：Quantum geometric properties and anomalous Hall effects in twisted bilayers报告题目：Quantum geometric properties and anomalous Hall effects in twisted bilayers 报告时间：2024年5月16日（周四）15:30 报告地点：鼓楼校区唐仲英楼B501 报 告 人：Wang Yao, The University of Hong Kong 摘 要：This talk will discuss quantum geometric properties of electrons in twisted homobilayer semiconductors arising from the layer pseudospin when twisting introduces its texture in real and momentum spaces. In small angle twisted TMDs, real-space Berry curvature from the moiré-patterned layer pseudospin texture realizes an effective magnetic field that underlies the emergence of quantum anomalous Hall effects recently observed in twisted MoTe2. We show that the FM and AFM QAH states in twisted TMDs moiré feature an intrinsic dipole Hall effect, which leads to a novel magnetoelectricity and allows contact-free detection of the topological transitions to QAH states. I will also discuss a variant of the fluxed three-orbital tight-binding model we initially proposed for twisted TMDs, describing a semimetal at integer filling, where DMRG calculations reveal fractional QAH phases at fractional fillings of its gapless flat band. If time allows, I will also discuss linear and nonlinear responses of quantum geometric origins from momentum space layer texture, including the time-reversal even linear Hall counter flow and nonlinear dynamical Hall effect of a crossed geometry. 报告人简介：Wang Yao obtained his BSc from Peking University in 2001, and PhD in physics from University of California, San Diego in 2006. He joined the University of Hong Kong in 2008, and rose through the academic ranks to Chair Professor of Physics in 2019. He is also a New Cornerstone Investigator. His group works in an interdisciplinary area across condensed matter physics, quantum physics, and optical physics, with current research interest in spin and pseudospin phenomena in 2D quantum materials and their layered structures. He has received honours including the OCPA Achievement in Asia Award, Nishina Asia Award, XPlorer Prize, Huang Kun Prize, and has been named by Clarivate Analytics in the list of Highly Cited Researchers in consecutive years since 2018. He is also elected Fellow of American Physical Society and Fellow of Optica.
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