Cornell University

This is a past event. Its details are archived for historical purposes.

The contact information may no longer be valid.

Please visit our current events listings to look for similar events by title, location, or venue.

Quantum Theory Seminar -Emergent QED3 from half-filled flat Chern bands - Xue-Yang (MIT)

Friday, March 31, 2023 at 3:30pm to 4:30pm

Virtual Event

Emergent QED3 from half-filled flat Chern bands

In recent years, two-dimensional Dirac materials patterned with a superlattice structure have emerged as a rich platform for exploring correlated and topological quantum matter. In this work, we propose that by subjecting Dirac electrons to a periodic magnetic field with triangular lattice symmetry it is possible to realize a \emph{quantum critical phase} of $N_f=3$ Dirac fermion species strongly coupled to an emergent gauge field, or 2+1-D quantum electrodynamics (QED$_3$). We demonstrate explicitly  that the QED$_3$ phase naturally arises from a Dirac composite fermion (CF) picture, where the periodic magnetic field manifests as a periodic CF potential and transforms the CF Fermi surface into gapless Fermi points. We further show that by breaking the particle-hole symmetry of the TI surface -- either by doping or by introducing a periodic electrostatic potential with zero mean -- our quantum critical phase gives way to a sequence of fractional Chern insulator phases. Our theory illustrates the rich menagerie of quantum phases possible around half filling of a flat Chern band. 

Faculty Hosts: Chao-Mian Jian, and Debanjan Chowdhury

Streaming site:

Google Calendar iCal Outlook
Event Type




University Themes



physics, lassp, quantum_site, quantum_theory, quantum_lassp





Contact E-Mail


Xue-Yang Song

Speaker Affiliation


Disability Access Information

If you need accommodations to participate in this event, please contact us as soon as possible.

Open To

Open to the Public

Recent Activity