Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 53: Quantum Impurities and Kondo Physics
TT 53.7: Vortrag
Mittwoch, 14. März 2018, 11:00–11:15, HFT-FT 131
Two-stage Kondo effect in the presence of induced pairing in T-shaped double quantum dots — •Krzysztof Wójcik1,2 and Ireneusz Weymann2 — 1Institute of Physics, Polish Academy of Sciences, 60-197 Poznań, Poland — 2Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland
In this contribution the transport properties of a T-shaped double quantum dot (QD) proximized by a superconductor (SC) are discussed. In particular, the linear response conductance and the Seebeck coefficient, calculated by means of the numerical renormalization group method, are analyzed. In the absence of SC and for relatively small inter-dot hopping matrix element, the two-stage Kondo screening is known to be present in the system [1]. We show that, generally, the effects of coupling of only one QD to SC may be qualitatively understood as a consequence of effective reduction of the Coulomb interactions. In particular, the dependence of the Kondo temperature corresponding to the two-stage Kondo screening on the coupling to SC lead is explained in this way. Similarly, one can describe the quantum phase transition between the Kondo-like state and the state characterized by the local density of states dominated by the Andreev bound states. However, the coupling of both QDs to SC results in creation and destruction of nonlocal pairs, which tends to additionally enhance the formation of total Kondo singlet. The consequences for transport properties in such a scenario are discussed.
[1] P. S. Cornaglia, D. R. Grempel, Phys. Rev. B 71, 075305 (2005).