Topological exciton Fermi surfaces in two-component fractional quantized Hall insulators

Abstract

A wide variety of two-dimensional electron systems (2DES) allow for independent control of the total and relative charge density of two-component fractional quantum Hall (FQH) states. In particular, a recent experiment on bilayer graphene (BLG) observed a continuous transition between a compressible and incompressible phase at total filling ${\nu }_T=\frac{1}{2}$ as charge is transferred between the layers, with the remarkable property that the incompressible phase has a finite interlayer polarizability. We argue that this occurs because the topological order of ${\nu }_T=\frac{1}{2}$ systems supports a novel type of interlayer exciton that carries Fermi statistics. If the fermionic excitons are lower in energy than the conventional bosonic excitons (i.e., electron-hole pairs), they can form an emergent neutral Fermi surface, providing a possible explanation of an incompressible yet polarizable state at ${\nu }_T=\frac{1}{2}$. We perform exact diagonalization studies which demonstrate that fermionic excitons are indeed lower in energy than bosonic excitons. This suggests that a "topological exciton metal" hidden inside a FQH insulator may have been realized experimentally in BLG. We discuss several detection schemes by which the topological exciton metal can be experimentally probed.

References in corpus (7)

• Robust fractional quantum Hall states and continuous quantum phase transitions in a half-filled bilayer graphene Landau level
• Valley polarization and susceptibility of composite fermions around nu=3/2
• Neutral Fermion Excitations in the Moore-Read state at ν=5/2
• Continuous transitions between composite Fermi liquid and Landau Fermi liquid: a route to fractionalized Mott insulators
• Numerical Calculation of the Neutral Fermion Gap at $\nu =5/2$
• Superconducting Order Parameter for the Even-denominator Fractional Quantum Hall Effect
• Evidence for a topological "exciton Fermi sea" in bilayer graphene

Cited by in corpus (12)

• Evidence for a Monolayer Excitonic Insulator
• Correlated interlayer exciton insulator in double layers of monolayer WSe2 and moiré WS2/WSe2
• Landau Quantization and Highly Mobile Fermions in an Insulator
• Extraction of many-body Chern number from a single wave function
• A cascade of phase transitions in an orbitally mixed half-filled Landau level
• Widely Tunable Quantum Phase Transition from Moore-Read to Composite Fermi Liquid in Bilayer Graphene
• Excitons in the Fractional Quantum Hall Effect
• Doping a Mott insulator with excitons in moiré bilayer: fractional superfluid, neutral Fermi surface and Mott transition
• Evidence for a topological "exciton Fermi sea" in bilayer graphene
• Correlated Topological Mixed-Valence Insulators in Moiré Hetero-Bilayers
• Hetero-Orbital Two-Component Fractional Quantum Hall States in Bilayer Graphene
• Role of the compensating current in the weak Josphson coupling regime: An extended study on excitonic Josephson junctions