Condensed Matter Seminar: Michael Zaletel, Princeton University - “Evidence for a topological “exciton metal” in bilayer graphene”

Graphene based heterostructures have emerged as a pristine platform for exploring the interplay of symmetry, topology and non-Abelian excitations in the quantum Hall regime. In bilayer graphene, an electric field perpendicular to the bilayer can be used to engineer crossings between Landau levels, leading to a rich array of multi-component quantum Hall phases.
At one such crossing, the Young Lab at UCSB has recently observed a phase transition between an even-denominator fractional quantum Hall state and a compressible phase at half-filling of a Landau level. Based on a combination of theoretical, numerical and experimental evidence, I will argue that this transition gives rise to an “exciton metal,” a Fermi sea of topologically non-trivial excitons. This novel phase of matter would have dramatic transport signatures and provide new evidence for the existence of the non-Abelian Moore-Read phase.