Complex state induced by impurities in multiband superconductors
Abstract
We study the role of impurities in a two-band superconductor, and elucidate the nature of the recently predicted transition from s_{+-} state to s_{++} state induced by interband impurity scattering. Using a Ginzburg-Landau theory, derived from microscopic equations, we demonstrate that close to T_c this transition is necessarily a direct one, but deeper in the superconducting state an intermediate complex state appears. This state has a distinct order parameter, which breaks the time-reversal symmetry, and is separated from the s_{+-} and s_{++} states by phase transitions. Based on our results, we suggest a phase diagram for systems with weak repulsive interband pairing, and discuss its relevance to iron-based superconductors.
Cite
@article{arxiv.1306.4268,
title = {Complex state induced by impurities in multiband superconductors},
author = {Valentin Stanev and Alexei E. Koshelev},
journal= {arXiv preprint arXiv:1306.4268},
year = {2014}
}
Comments
7 pages, 4 figures, several typos fixed, Fig 1 replaced