Two-gap superconductivity: interband interaction in the role of external   field
  We show that weak interband pair-transfer interaction affects weaker-superconductivity component of a two-gap system as an external field associated with the order parameter, similarly to an external magnetic field for ferromagnetics or an external electric field for ferroelectrics. 
Artjom Vargunin, K\"ullike R\"ago, and Teet \"Ord
cond-mat.supr-con