Andreev transport in a correlated ferromagnet-quantum-dot-superconductor device

I. Weymann; K. P. Wójcik

doi:10.1103/PhysRevB.92.245307

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Andreev transport in a correlated ferromagnet-quantum-dot-superconductor device

I. Weymann, K. P. Wójcik

DOI 10.1103/PhysRevB.92.245307 · Physical Review B

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Abstract

The spin-resolved Andreev reflection processes in a hybrid ferromagnet-quantum-dot-superconductor device are theoretically studied. In particular, the transport coefficients, such as the Andreev transmission as well as the linear-response Andreev conductance, are calculated by means of the numerical renormalization group method. It is shown that, generally, transport properties are conditioned by the interplay of correlations leading to the Kondo effect, superconducting proximity effect, and ferromagnetic-contact-induced exchange field. The exchange field is shown to greatly affect the low-energy behavior of the Andreev transmission by splitting the Kondo resonance. Moreover, it leads to a nonmonotonic dependence of the Andreev conductance on the dot level position. At low temperatures, the conductance has a peak at the particle-hole symmetry point, which however becomes quickly suppressed with increasing the temperature. The mechanisms responsible for those effects are thoroughly discussed.