1203.4554 (Victor Vakaryuk et al.)

Phase soliton and pairing symmetry of a two-band superconductor: Role of
the proximity effect    [PDF]

Victor Vakaryuk, Valentin Stanev, Wei-Cheng Lee, Alex Levchenko

We suggest a mechanism which allows for tuning the energy of a topological defect -- phase soliton -- formed in the relative phase of the superconducting gaps of a two-band superconductor. This mechanism exploits the proximity effect with a conventional s-wave superconductor which favors the alignment of the phases of the two-band superconductor. Such effect leads to the reduction of the energy of the phase soliton for the s+- pairing in which the equilibrium phases of the bands are pi-shifted. We show that for a strong proximity effect the energy of the soliton can be reduced below the energy of the soliton-free state, thus making it thermodynamically stable. Based on this observation we consider an experimental setup, applicable both for stable and metastable solitons, which can distinguish between s+- and s++ types of symmetry. We also discuss relevance of our results to the iron-based multiband superconductors.

View original: http://arxiv.org/abs/1203.4554