Holographic Polarons, the Metal-Insulator Transition and Massive Gravity

TL;DR

This paper explores how massive gravity models can holographically simulate realistic materials with momentum relaxation, revealing a novel interaction-driven metal-insulator transition caused by polaron formation that affects conductivity and spectral properties.

Contribution

It introduces a new class of holographic models with phonon-electron interactions leading to a metal-insulator transition, expanding the understanding of holographic duals for complex materials.

Findings

Polaron formation dominates conductivity behavior.

Spectral weight shifts above a mass gap during transition.

Characterized polaron gap, width, and dispersion.

Abstract

Massive gravity is holographically dual to `realistic' materials with momentum relaxation. The dual graviton potential encodes the phonon dynamics and it allows for a much broader diversity than considered so far. We construct a simple family of isotropic and homogeneous materials that exhibit an interaction-driven Metal-Insulator transition. The transition is triggered by the formation of polarons -- phonon-electron quasi-bound states that dominate the conductivities, shifting the spectral weight above a mass gap. We characterize the polaron gap, width and dispersion.