Transport properties of a holographic model with novel gauge-axion coupling

TL;DR

This paper explores a holographic model with a new gauge-axion coupling that results in antisymmetric off-diagonal conductivity components, resembling Hall conductivity, and enables metal-insulator transitions.

Contribution

It introduces a novel gauge-axion coupling in holography, leading to unique transport phenomena such as antisymmetric conductivity and metal-insulator transitions.

Findings

Emergence of antisymmetric off-diagonal conductivity components

Conductivity behavior similar to Hall effect

Model exhibits metal-insulator transition

Abstract

We investigate the transport properties within a holographic model characterized by a novel gauge-axion coupling. A key innovation is the introduction of the direct coupling between axion fields, the antisymmetric tensor, and the gauge field in our bulk theory. This novel coupling term leads to the emergence of nondiagonal components in the conductivity tensor. An important characteristic is that the off-diagonal elements manifest antisymmetry. Remarkably, the conductivity behavior in this model akin to that of Hall conductivity. Additionally, this model can also achieve metal-insulator transition.