Title:Hall Crystals and Chiral Cavity Control—— Correlation and Topology in Quantum Materials
Speaker:Ze-Xun Lin, the University of Cambridge
Time:2025-12-18 10：30
Venue:Room W105, Physics Building
Abstract:Recent advances in moire materials and cavity quantum electrodynamics have opened new pathways to engineer correlated and topological phases of matter. In this talk, I will present two emerging directions. First, I will discuss our recent theory of Hall crystals in fractionally filled Chern bands, where a Wigner crystal of holes coexists with a topological electron fluid. Using Hartree–Fock calculations in broken-symmetry states, we identify crystalline phases whose electronic structure and transport signatures are consistent with a nontrivial Chern number and with the re-entrant anomalous Hall features observed in twisted MoTe2.Next, I will introduce a mechanism by which a time-reversal-breaking chiral cavity reshapes the exciton spectrum, driving an s-to-p orbital transition in the exciton ground state. This provides a broadly applicable route to cavity-controlled orbital and topological engineering in 2D semiconductors.
I will conclude with earlier work on nonlinear-phonon–induced control of interlayer Dzyaloshinskii–Moriya interactions.
Bio:Ze-Xun Lin received his B.Sc. in Physics from Nanjing University (2013–2017) and his Ph.D. from the University of Texas at Austin (2017–2023), where he was co-supervised by Gregory Fiete and Allan MacDonald. He was a postdoctoral scholar at UCLA from 2023 to 2025 and is currently a postdoctoral researcher in the Theory of Condensed Matter group at the University of Cambridge. His research focuses on the interplay of correlation and topology in moire quantum materials, cavity-engineered exciton, quantum Hall and superconducting phases, and transport phenomena in frustrated magnetic systems such as pyrochlore spin ice.
