Holographic Superconductors

TL;DR

This paper reviews and extends the holographic superconductor model by exploring all scalar charges, analyzing backreaction effects, and demonstrating Type II superconductivity with magnetic field responses.

Contribution

It provides a comprehensive analysis of holographic superconductors across all scalar charges, including backreaction effects and magnetic field behavior, revealing new black hole instabilities and Type II characteristics.

Findings

Qualitative behavior similar across all charges

Discovery of a new black hole instability at small charge

Holographic superconductors exhibit Type II behavior with magnetic fields

Abstract

It has been shown that a gravitational dual to a superconductor can be obtained by coupling anti-de Sitter gravity to a Maxwell field and charged scalar. We review our earlier analysis of this theory and extend it in two directions. First, we consider all values for the charge of the scalar field. Away from the large charge limit, backreaction on the spacetime metric is important. While the qualitative behaviour of the dual superconductor is found to be similar for all charges, in the limit of arbitrarily small charge a new type of black hole instability is found. We go on to add a perpendicular magnetic field B and obtain the London equation and magnetic penetration depth. We show that these holographic superconductors are Type II, i.e., starting in a normal phase at large B and low temperatures, they develop superconducting droplets as B is reduced.