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 $(\lambda _{{\rm ab}})$ 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.