Holographic Superfluids and Superconductors in Dilaton-Gravity

TL;DR

This paper explores holographic models of superfluids and superconductors incorporating a dilaton field, revealing unique low-temperature behaviors and phase transition characteristics that enhance understanding of condensed matter systems.

Contribution

It introduces dilaton-extended holographic models that better capture low-temperature phenomena and phase behaviors in superfluids and superconductors.

Findings

Dilaton fields break scale invariance in the IR, leading to insulating or solid phases.

Holographic superconductors exhibit Type II behavior and vortex phases.

Critical magnetic fields and penetration depth can remain finite at low temperatures.

Abstract

We investigate holographic models of superfluids and superconductors in which the gravitational theory includes a dilatonic field. Dilaton extensions are interesting as they allow us to obtain a better description of low temperature condensed matter systems. We focus on asymptotically AdS black hole configurations, which are dual to field theories with conformal ultraviolet behavior. A nonvanishing value of the dilaton breaks scale invariance in the infrared and is therefore compatible with the normal phase being insulating (or a solid in the fluid mechanical interpretation); indeed we find that this is the case at low temperatures and if one appropriately chooses the parameters of the model. Not only the superfluid phase transitions, but also the response to external gauge fields is analyzed. This allows us to study, among other things, the vortex phase and to show that these holographic superconductors are also of Type II. However, at low temperatures they can behave in a qualitatively different way compared to their analogues without the dilaton: the critical magnetic fields and the penetration depth can remain finite in the small T/T_c limit.