Mixed order parameter symmetries in cuprate superconductors
  The recent observation of an inflection point in the temperature dependence of the in-plane magnetic field dependence (lambda_ab) is investigated within a two-band model with coupled order parameters of different symmetries. While the dominant order parameter has d-wave symmetry, the smaller one is of s-wave symmetry. Superconductivity is robust in the d-wave channel and induced via interband interactions in the s-wave subsystem. 
A. Bussmann-Holder, R. Khasanov, A. Shengelaya, A. Maisuradze, F. La   Mattina, H. Keller and K. A. Mueller