Eur. Phys. J. B (2015) 88: 329
https://doi.org/10.1140/epjb/e2015-60574-6

Regular Article

Generalized Blonder-Tinkham-Klapwijk theory and conductance spectra with particle-hole mixing interface potential

¹ Dipartimento di Fisica “E.R. Caianiello”, Università degli Studi di Salerno, Via Giovanni Paolo II, 84084 Fisciano ( SA), Italy
² CNR-SPIN Salerno, Via Giovanni Paolo II, 84084 Fisciano ( SA), Italy

^a e-mail: citro@sa.infn.it

Received: 15 July 2015
Received in final form: 22 October 2015
Published online: 9 December 2015

Abstract

We extend the Blonder-Tinkham-Klapwijk treatment including particle-hole mixing boundary conditions in the Bogoliubov-de Gennes scattering problem to describe anomalous conductance features often reported in normal-metal/superconductor junctions. We calculate the differential conductance spectra and show that conductance dips, not expected in the standard formulation, can be explained in terms of a phase π-shift between the bulk and the interface order parameter. A tight-binding model is also introduced to give a quantitative description of the phase-shift in terms of the transparency and polarization of the interface. We characterize the physics arising from particle-hole mixing boundary conditions at the interface and its effects on the conductance anomalies in superconductor-normal heterostructures.