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Friday, March 31, 2023 at 3:30pm to 4:30pm
Virtual EventEmergent 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:
https://www.youtube.com/@quantumtheoryseminar6651/streams
Free
Xue-Yang Song
MIT
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