Compressible Matter at a Holographic Interface

TL;DR

This paper investigates the holographic interface between a fractional topological insulator and an ordinary insulator, revealing a compressible, gapless state with hyperscaling violation and Fermi surface characteristics at finite density.

Contribution

It introduces a holographic model of a topological insulator interface with finite density, demonstrating a novel compressible state with gapless excitations and hyperscaling violation.

Findings

Identifies a symmetry-preserving compressible state at low temperatures.

Shows excitations exhibit hyperscaling violation.

Finds evidence of a Fermi surface at finite density.

Abstract

We study the interface between a fractional topological insulator and an ordinary insulator, both described using holography. By turning on a chemical potential we induce a finite density of matter localized at the interface. These are gapless surface excitations which are expected to have a fermionic character. We study the thermodynamics of the system, finding a symmetry preserving compressible state at low temperatures, whose excitations exhibit hyperscaling violation. These results are consistent with the expectation of gapless fermionic excitations forming a Fermi surface at finite density.