Bosonic Analogue of Dirac Composite Fermi Liquid

TL;DR

This paper proposes a novel bosonic metallic state with particle-hole symmetry, featuring composite fermions with quadratic band touching and Berry flux, extending the Dirac composite Fermi liquid concept to bosons.

Contribution

It introduces a bosonic analogue of the Dirac composite Fermi liquid, including states with and without Berry flux, and explores their symmetry properties and potential realizations.

Findings

Identifies a particle-hole symmetric bosonic metallic state with quadratic band touching.

Constructs an alternative state without Berry flux, distinguished by inversion symmetry.

Discusses experimental and simulation signatures of these phases.

Abstract

We introduce a particle-hole-symmetric metallic state of bosons in a magnetic field at odd-integer filling. This state hosts composite fermions whose energy dispersion features a quadratic band touching and corresponding $2\pi$ Berry flux protected by particle-hole and discrete rotation symmetries. We also construct an alternative particle-hole symmetric state---distinct in the presence of inversion symmetry---without Berry flux. As in the Dirac composite Fermi liquid introduced by Son, breaking particle-hole symmetry recovers the familiar Chern-Simons theory. We discuss realizations of this phase both in 2D and on bosonic topological insulator surfaces, as well as signatures in experiments and simulations.