Friday, October 18th at 11 am
Room 5209 at The Graduate Center, CUNY

Jie Wang, Flatiron Institute
https://www.simonsfoundation.org/team/jie-wang/

"Emergent Dirac fermions in Composite Fermi Liquids".

Abstract: Interacting electrons in high magnetic fields exhibit rich physical phenomena including the gapped fractional quantum Hall effects and the gapless states. The composite Fermi liquids (CFLs) are gapless states that can occur at even denominator Landau level fillings. Due to the celebrated work of Halperin, Lee and Read (94), the CFLs were understood as Fermi liquids of composite fermions, which are bound states of electrons and electromagnetic flux quanta. However, at 1/2 filling, it is not obvious why the HLR description is consistent with the particle hole symmetry. Motivated by this, recently Son (15) proposed an alternative description for CFLs at 1/2, according to which the composite fermions are instead emergent Dirac fermions. Importantly, Son’s theory predicts a Pi Berry curvature singularity at the composite Fermi sea center. In this talk, I will focus on the Berry phase aspect of CFLs, and talk about the emergent Dirac fermions at low energy at one-half and other generic filling fractions.