Quantum Hall Superfluids in Topological Insulator Thin Films

TL;DR

This paper predicts the emergence of quantum Hall superfluid states in topological insulator thin films under magnetic fields, highlighting their unique transport properties and the influence of dielectric constants on coherence and sound velocity.

Contribution

It introduces a novel magnetic field-induced ordered state in topological insulator thin films with spontaneous inter-surface coherence and analyzes its physical properties.

Findings

Coherence persists over larger layer separations with high dielectric constants.

Superfluid sound velocity decreases due to dielectric effects.

The $ u_T=0$ state lacks edge modes, affecting transport behavior.

Abstract

Three-dimensional topological insulators have protected Dirac-cone surface states. In this paper we propose magnetic field induced topological insulator thin film ordered states in which coherence is established spontaneously between top and bottom surfaces. We find that the large dielectric constants of these materials increases the layer separation range over which coherence survives and decreases the superfluid sound velocity, but has little influence on superfluid density or charge gap. The coherent state at total Landau-level filling factor $\nu_T=0$ is predicted to be free of edge modes, qualitatively altering its transport phenomenology.