Nonequilibrium Transport through a Spinful Quantum Dot with Superconducting Leads

Brian Møller Andersen; Karsten Flensberg; Verena Koerting; Jens Paaske

doi:10.1103/PhysRevLett.107.256802

Nonequilibrium Transport through a Spinful Quantum Dot with Superconducting Leads

Brian Møller Andersen, Karsten Flensberg, Verena Koerting, Jens Paaske

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Abstract

We study the nonlinear cotunneling current through a spinful quantum dot contacted by two superconducting leads. Applying a general nonequilibrium Green function formalism to an effective Kondo model, we study the rich variation in the IV characteristics with varying asymmetry in the tunnel coupling to source and drain electrodes. The current is found to be carried, respectively, by multiple Andreev reflections in the symmetric limit, and by spin-induced Yu-Shiba-Rusinov bound states in the strongly asymmetric limit. The interplay between these two mechanisms leads to qualitatively different IV characteristics in the crossover regime of intermediate symmetry, consistent with recent experimental observations of negative differential conductance and repositioned conductance peaks in subgap cotunneling spectroscopy.

Original language	English
Journal	Physical Review Letters
Volume	107
Issue number	25
Pages (from-to)	256802
Number of pages	5
ISSN	0031-9007
DOIs	https://doi.org/10.1103/PhysRevLett.107.256802
Publication status	Published - 14 Dec 2011

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title = "Nonequilibrium Transport through a Spinful Quantum Dot with Superconducting Leads",

abstract = "We study the nonlinear cotunneling current through a spinful quantum dot contacted by two superconducting leads. Applying a general nonequilibrium Green function formalism to an effective Kondo model, we study the rich variation in the IV characteristics with varying asymmetry in the tunnel coupling to source and drain electrodes. The current is found to be carried, respectively, by multiple Andreev reflections in the symmetric limit, and by spin-induced Yu-Shiba-Rusinov bound states in the strongly asymmetric limit. The interplay between these two mechanisms leads to qualitatively different IV characteristics in the crossover regime of intermediate symmetry, consistent with recent experimental observations of negative differential conductance and repositioned conductance peaks in subgap cotunneling spectroscopy.",

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T1 - Nonequilibrium Transport through a Spinful Quantum Dot with Superconducting Leads

AU - Andersen, Brian Møller

AU - Flensberg, Karsten

AU - Koerting, Verena

AU - Paaske, Jens

PY - 2011/12/14

Y1 - 2011/12/14

N2 - We study the nonlinear cotunneling current through a spinful quantum dot contacted by two superconducting leads. Applying a general nonequilibrium Green function formalism to an effective Kondo model, we study the rich variation in the IV characteristics with varying asymmetry in the tunnel coupling to source and drain electrodes. The current is found to be carried, respectively, by multiple Andreev reflections in the symmetric limit, and by spin-induced Yu-Shiba-Rusinov bound states in the strongly asymmetric limit. The interplay between these two mechanisms leads to qualitatively different IV characteristics in the crossover regime of intermediate symmetry, consistent with recent experimental observations of negative differential conductance and repositioned conductance peaks in subgap cotunneling spectroscopy.

AB - We study the nonlinear cotunneling current through a spinful quantum dot contacted by two superconducting leads. Applying a general nonequilibrium Green function formalism to an effective Kondo model, we study the rich variation in the IV characteristics with varying asymmetry in the tunnel coupling to source and drain electrodes. The current is found to be carried, respectively, by multiple Andreev reflections in the symmetric limit, and by spin-induced Yu-Shiba-Rusinov bound states in the strongly asymmetric limit. The interplay between these two mechanisms leads to qualitatively different IV characteristics in the crossover regime of intermediate symmetry, consistent with recent experimental observations of negative differential conductance and repositioned conductance peaks in subgap cotunneling spectroscopy.

U2 - 10.1103/PhysRevLett.107.256802

DO - 10.1103/PhysRevLett.107.256802

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SN - 0031-9007

VL - 107

SP - 256802

JO - Physical Review Letters

JF - Physical Review Letters

IS - 25

ER -

Nonequilibrium Transport through a Spinful Quantum Dot with Superconducting Leads

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