In-plane magnetic field vs. temperature phase diagram of a quasi-2D frustrated multiband superconductor

TL;DR

This study explores the phase diagram of a quasi-2D frustrated three-band superconductor under in-plane magnetic fields and temperature, revealing conditions for chiral phases and their dependence on interband couplings.

Contribution

It provides a detailed analysis of the conditions under which chiral superconducting phases occur in a frustrated multiband superconductor, highlighting the effects of interband coupling strength.

Findings

Chiral phases appear in a narrow region for weak interband coupling.

The chiral region narrows and vanishes at low temperatures for weak coupling.

Stronger interband couplings broaden the chiral phase region.

Abstract

Motivated by the recent discovery of iron-based superconductors, with high critical temperatures and multiple bands crossing the Fermi level, we address the conditions for the presence of chiral superconducting phases configurations in the in-plane magnetic field vs. temperature phase diagram of a quasi-2D frustrated three-band superconductor. Due to Zeeman splitting, the coupled superconducting gap equations present a complex set of solutions. For weak interband couplings, chiral configurations are only attained in a narrow strip of the in-plane magnetic field vs. temperature phase diagram. This strip of chiral states becomes narrower and disappears at low temperatures, giving way to a first-order transition between non-chiral superconducting states. For stronger interband couplings, the chiral strip is much broader, if the interband couplings are approximately equal; otherwise, the chiral region is expected to be completely absent of the phase diagram.