Charge transport across a mesoscopic superconductor normal metal junction: coherence and decoherence effects

We present a simple scattering approach to the charge transport across a realistic superconductor–normal injector interface of a finite transmittance that is modeled by a double-barrier mesoscopic junction. For a d-wave pairing symmetry, our calculations combine a fully quantum-mechanical scattering formalism with a self-consistent estimation of Andreev reflection coefficients within the quasi-classical Eilenberger equation scheme for a free specular superconducting surface. Numerical simulations confirm experimental criteria of Cucolo for the unconventional superconducting origin of conductance anomalies in high-temperature oxides. A discussion of dephasing effects caused by inelastic scattering processes in the interlayer and their impact on the conductance spectra is given.