Nonequilibrium transport via spin-induced sub-gap states in superconductor/quantum dot/normal metal cotunnel junctions

Abstract

We study low-temperature transport through a Coulomb blockaded quantum dot (QD) contacted by a normal (N), and a superconducting (S) electrode. Within an effective cotunneling model the conduction electron self energy is calculated to leading order in the cotunneling amplitudes and subsequently resummed to obtain the nonequilibrium T-matrix, from which we obtain the nonlinear cotunneling conductance. For even occupied dots the system can be conceived as an effective S/N-cotunnel junction with subgap transport mediated by Andreev reflections. The net spin of an odd occupied dot, however, leads to the formation of sub-gap resonances inside the superconducting gap which gives rise to a characteristic peak-dip structure in the differential conductance, as observed in recent experiments.

13 pages, 13 figures (new version contains reformulations and corrections of typos etc)

References in corpus (10)

• Spectral properties of locally correlated electrons in a BCS superconductor
• Even-odd effect in Andreev Transport through a Carbon Nanotube Quantum Dot
• Kondo-Enhanced Andreev Tunneling in InAs Nanowire Quantum Dots
• Real-time diagrammatic approach to transport through interacting quantum dots with normal and superconducting leads
• Numerical Renormalization Group Approach to a Quantum Dot Coupled to Normal and Superconducting Leads
• Superconductivity-enhanced bias spectroscopy in carbon nanotube quantum dots
• Influence of the pair coherence on the charge tunneling through a quantum dot connected to a superconducting lead
• Meservey-Tedrow-Fulde effect in a quantum dot embedded between metallic and superconducting electrodes
• Andreev Bound States in the Kondo Quantum Dots Coupled to Superconducting Leads
• Enhanced Andreev Tunneling via the Kondo Resonance in a Quantum Dot at Finite Bias

Cited by in corpus (8)

• Hard gap in epitaxial semiconductor-superconductor nanowires
• Zero-bias anomaly in a nanowire quantum dot coupled to superconductors
• Shiba states and zero-bias anomalies in the hybrid normal-superconductor Anderson model
• Yu-Shiba-Rusinov states of impurities in a triangular lattice of NbSe${}_2$ with spin orbit coupling
• Decoherence effect on the Fano lineshapes in double quantum dots coupled between normal and superconducting leads
• Renormalization effects in interacting quantum dots coupled to superconducting leads
• Quantum Monte Carlo study of nonequilibrium transport through a quantum dot coupled to normal and superconducting leads
• Odd-triplet superconductivity in single-level quantum dots