COLLOQUIUM 2025
Moiré Magic: Uncovering Band Topology in Twisted WSe₂ Bilayers
| Speaker | Dr Fan Zhang, The University of Texas at Austin, Texas, USA |
| Date/Time | Friday, 25 Apr, 11AM |
| Location | Webinar |
| Host | Asst/Prof Anjan Soumyanarayanan |
| Registration link | https://forms.office.com/r/XSkJvbDyxH (Note: For registration, please use Zoom-registered email address) |
Abstract
Imagine if a slight twist between two layers of atoms could unlock entirely new behaviors in a material. In this talk, we explore how a small-angle twist in tungsten diselenide (WSe₂), a two-dimensional material, creates a moiré pattern that reshapes its electronic landscape. This twist not only alters the way electrons move and interact, but also gives rise to exotic quantum states hidden within the material’s structure.
I will present a combined experimental and theoretical framework designed to uncover the band topology in small-angle twisted WSe₂ bilayers. By combining high-resolution scanning tunneling microscopy/spectroscopy with a theoretical continuum model, we map out how the twist modifies the local density of electronic states—especially in the K valley—and influences a property we call layer pseudospin. These insights reveal how the interplay between the moiré potential and interlayer tunneling creates topological band, further leads to exotic quantum phenomena like quantum anomalous Hall effect.
Biography
Fan Zhang is a postdoctoral research fellow at Chih-Kang Shih’s group in the Department of Physics at The University of Texas at Austin. He got his B.S. degree from University of Science and Technology of China and received his Ph.D. in 2021 from Virginia Tech, where his research centered on two-dimensional ferroelectric materials.
His current work focuses on STM and ARPES study of low-dimensional electronic systems especially twistronics. He is dedicated to advancing novel techniques, with a notable accomplishment being the development of device-STM. His contributions resulted in several high impact publications.