Metal-insulator transition in holography

TL;DR

This paper demonstrates a holographic model exhibiting a quantum phase transition from metal to insulator driven by interactions, characterized by distinct optical and resistivity behaviors in each phase.

Contribution

It introduces a holographic approach with a helical lattice to model a transition between metallic and insulating phases, capturing translation symmetry effects.

Findings

Metallic phase shows a sharp Drude peak and resistivity increasing with temperature.

Insulating phase exhibits a mid-infrared peak and resistivity decreasing with temperature.

The model identifies the near horizon geometry corresponding to the insulating state.

Abstract

We exhibit an interaction-driven metal-insulator quantum phase transition in a holographic model. Use of a helical lattice enables us to break translation invariance while preserving homogeneity. The metallic phase is characterized by a sharp Drude peak and a d.c. resistivity that increases with temperature. In the insulating phase the Drude spectral weight is transferred into a `mid-infrared' peak and to energy scales of order the chemical potential. The d.c. resistivity now decreases with temperature. In the metallic phase, operators breaking translation invariance are irrelevant at low energy scales. In the insulating phase, translation symmetry breaking effects are present at low energies. We find the near horizon extremal geometry that captures the insulating physics.