Influence of intradot Coulomb correlations on the Andreev reflection in a ferromagnetic metal/quantum dot/superconductor hybrid junction

摘要

Spin-dependent tunneling through a quantum dot coupled to one ferromagnetic and one superconducting electrodes is studied in the Andreev reflection (AR) regime. Electrical conductance is calculated within the nonequilibrium Green function technique. Features of the AR current involved by the intradot Coulomb correlations (or the dot's charging energy U) and in the presence of the Zeeman splitting of the dot discrete level are analyzed in both linear and nonlinear transport regimes. A new interference effect due to AR is predicted to appear in the case of a weak on-dot repulsion. Strong Coulomb correlations studied in nonequilibrium situation revealed significant modifications of the AR differential conductance occurring only in case of spin-polarized transmission. Origin of a variety of the multipeak structure of the conductance for the system with the interacting quantum dot, as well as the conditions for the perfect U-dependent AR transmission are also discussed.