Abstract
We study the role of impurities in a two-band superconductor, and elucidate the nature of the recently predicted transition from the state to the state induced by interband impurity scattering. Using a Ginzburg-Landau theory, derived from microscopic equations, we demonstrate that close to 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 and states by continuous 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.
- Received 25 June 2013
- Revised 21 February 2014
DOI:https://doi.org/10.1103/PhysRevB.89.100505
©2014 American Physical Society