Phase transitions in a holographic s+p model with backreaction

TL;DR

This paper explores the phase structure of a holographic s+p superconductor model with backreaction, revealing complex phase transitions, including first-order and reentrant types, influenced by the strength of backreaction.

Contribution

It extends previous probe limit studies by incorporating full backreaction, uncovering new phase behaviors and detailed phase diagrams for the s+p superconductor model.

Findings

Reentrant phase transitions observed in the model.

First order phase transitions with swallow tail free energy curves.

The s+p coexisting phase region varies with backreaction strength.

Abstract

In a previous paper (arXiv:1309.2204, JHEP 1311 (2013) 087), we present a holographic s+p superconductor model with a scalar triplet charged under an SU(2) gauge field in the bulk. We also study the competition and coexistence of the s-wave and p-wave orders in the probe limit. In this work we continue to study the model by considering the full back-reaction The model shows a rich phase structure and various condensate behaviors such as the "n-type" and "u-type" ones, which are also known as reentrant phase transitions in condensed matter physics. The phase transitions to the p-wave phase or s+p coexisting phase become first order in strong back-reaction cases. In these first order phase transitions, the free energy curve always forms a swallow tail shape, in which the unstable s+p solution can also play an important role. The phase diagrams of this model are given in terms of the dimension of the scalar order and the temperature in the cases of eight different values of the back reaction parameter, which show that the region for the s+p coexisting phase is enlarged with a small or medium back reaction parameter, but is reduced in the strong back-reaction cases.