Nonequilibrium Kondo effect by equilibrium numerical renormalization group method: The hybrid Anderson model subject to a finite spin bias

Abstract

We investigate Kondo correlations in a quantum dot with normal and superconducting electrodes, where a spin bias voltage is applied across the device and the local interaction $U$ is either attractive or repulsive. When the spin current is blockaded in the large-gap regime, this nonequilibrium strongly-correlated problem maps into an equilibrium model solvable by the numerical renormalization group method. The Kondo spectra with characteristic splitting due to the nonequilibrium spin accumulation are thus obtained at high precision. It is shown that while the bias-induced decoherence of the spin Kondo effect is partially compensated by the superconductivity, the charge Kondo effect is enhanced out of equilibrium and undergoes an additional splitting by the superconducting proximity effect, yielding four Kondo peaks in the local spectral density. In the charge Kondo regime, we find a universal scaling of charge conductance in this hybrid device under different spin biases. The universal conductance as a function of the coupling to the superconducting lead is peaked at and hence directly measures the Kondo temperature. Our results are of direct relevance to recent experiments realizing negative-$U$ charge Kondo effect in hybrid oxide quantum dots [Nat. Commun. \textbf{8}, 395 (2017)].

7 pages, 3 figures, the version accepted by Physical Review B

References in corpus (27)

• Continuous-time Monte Carlo methods for quantum impurity models
• The numerical renormalization group method for quantum impurity systems
• Real-time dynamics in Quantum Impurity Systems: A Time-dependent Numerical Renormalization Group Approach
• Sum-rule Conserving Spectral Functions from the Numerical Renormalization Group
• A Numerical Renormalization Group approach to Green's Functions for Quantum Impurity Models
• Spin Precession and Real Time Dynamics in the Kondo Model: A Time-Dependent Numerical Renormalization-Group Study
• On steady-state currents through nano-devices: a scattering-states numerical renormalization group approach to open quantum systems
• Many Body Effects on the Transport Properties of Single-Molecule Devices
• Shiba states and zero-bias anomalies in the hybrid normal-superconductor Anderson model
• Electron Attraction Mediated by Coulomb Repulsion
• Imaginary-time formulation of steady-state nonequilibrium: application to strongly correlated transport
• Numerical Renormalization Group Approach to a Quantum Dot Coupled to Normal and Superconducting Leads
• Nonequilibrium charge-Kondo transport through negative-U molecules
• Time evolution of the Kondo resonance in response to a quench
• Anderson impurity model in nonequilibrium: analytical results versus quantum Monte Carlo data
• Exact results for the Kondo screening cloud of two helical liquids
• Time-Dependent Numerical Renormalization Group Method for Multiple Quenches: Application to General Pulses and Periodic Driving
• Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime
• Kondo Resonance in the Presence of Spin-Polarized Currents
• Exact nonequilibrium transport in the topological Kondo effect
• Spin-charge separation and simultaneous spin and charge Kondo effect
• Quantum Monte Carlo study of nonequilibrium transport through a quantum dot coupled to normal and superconducting leads
• Steady-state spectra, current and stability diagram of a quantum dot: a non-equilibrium Variational Cluster Approach
• Direct Evidence for Suppression of the Kondo Effect due to Pure Spin Current
• Quantum phase transitions in a pseudogap Anderson-Holstein model
• Inelastic Kondo-Andreev tunnelings in a vibrating quantum dot
• Out-of-equilibrium Kondo Effect in a Quantum Dot: Interplay of Magnetic Field and Spin Accumulation

Cited by in corpus (6)

• Quantum Monte Carlo in the steady-state
• Well-defined Fano effect in the Andreev reflection process of a parallel double-quantum-dot structure
• Interplay of the Kondo effect with the induced pairing in electronic and caloric properties of T-shaped double quantum dots
• Ferromagnetic induced Kondo effect in graphene with a magnetic impurity
• Strongly correlated electrons in superconducting islands with fluctuating Cooper pairs
• Quantum phase transitions in superconductor--quantum-dot--superconductor Josephson structures with attractive intradot interaction