Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.24: Poster

Donnerstag, 26. März 2009, 15:00–17:30, P2

Transport through the quantum dot connected to external leads — •Agnieszka Donabidowicz-Kolkowska^1,2 and Tadeusz Domanski¹ — ¹Institute of Physics, Maria Curie-Sklodowska University,Lublin, Poland — ²Institute for Theoretical Physics, Technische Universität Dresden,Germany

In this work we study the transport properties of a single level quantum dot connected to two normal electrodes and/or one normal (N) and one superconducting (S) lead using the nonequilibrium Green*s function formalism. For a description of the N-QD-N/S junction we consider the single impurity Anderson model.The effects of the electron pair coherence, Coulomb interactions are discussed with a particular account of their influence on a charge tunnelling through the quantum dot. We observe that the long range off-diagonal superconducting order induces the proximity effect in the quantum dot due to a particle-hole mixing at small energies . Influence of the proximity effect on transport properties of the systems manifests itself in the Andreev conductance. Additionally, in presence of the strong on-dot correlations some qualitatively new features were observed. One of them is the zero bias anomaly which occurs due to formation of the Kondo state at sufficiently low temperatures. We show that quantum transport in superconducting devices is controlled by the interplay between the Kondo effect and Andreev reflection processes.