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

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.