Abstract: 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 moire-patterned layer pseudospin texture realizes an effective magnetic field  that underlies the emergence of quantum anomalous Hall effects recently observed in twisted MoTe2. The gate tunable ferromagnetic QAH at filling factor 1 further implies the existence of an altermagnetic orbital Chern insulator at filling factor 2, where sizable orbital magnetization makes possible field initialization of spin Neel order and Chern number, with the sign of Chern number electrically switchable at zero magnetic field. 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, nonlinear dynamical Hall effect of a crossed geometry, and interlayer electric multipoles driven by in-plane electric field.

Bio：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 from 2018 to 2023. He is also elected Fellow of American Physical Society and Fellow of Optica.