Conductance spectroscopy in ferromagnet-superconductor hybrids

We present a theoretical model for the proximity effect in F–SFF–F structures (where F is a ferromagnet and S is a superconductor) with non-collinear magnetization vectors in the F-layers and with arbitrary magnitudes of exchange fields. The electrical conductance of these structures is analyzed within the Keldysh–Usadel formalism in the diffusive regime as a function of the misorientation angle between magnetizations of the F-layers and transparencies of the SF and FF interfaces. We show that long-range triplet superconducting correlations manifest themselves either as a zero-bias peak in the case of perfect transparency of the FF interface, or as a two-peak structure in the case of finite transparency. The predicted features may serve as a diagnostic tool for the characterization of interfaces in superconducting hybrid structures.