KIC Postdoctoral Fellow Candidate: Yihang Zeng, PhD, Columbia University

Title: Novel Correlated Phenomena in Graphene Quantum Hall Double layers

Abstract: Coulomb coupled graphene double layers have been demonstrated to host novel correlated phenomena including Bose Einstein condensate of indirect interlayer exciton and two-component fractional quantum Hall effect. With newly developed device structure, we are able to acquire the multi-dimensional phase diagram of such novel phenomena in a wide parameter range. In the exciton superfluid phase we observed a crossover from BEC-like pairing to BCS-like pairing as the effective coupling strength and exciton population is tuned. Upon further decreasing the exciton density, the exciton superfluid transitions into a pinned exciton solid which melts into a superfluid at elevated temperature. At fractional filling, we mapped out the phase transition between different sequences of fractional quantum Hall states. We found a novel two-component non-abelian fractional quantum Hall state at 4/3 filling that might contain the long-sought Fibonacci anyons.