Josephson versus Kondo coupling in a quantum dot connected to two superconductors

Abstract

We apply a Gutzwiller-like variational technique to study Josephson conduction across a quantum dot with an odd number of electrons connected to two superconducting leads. Our method projects out all states on the dot but the Kondo singlet and is valid when Kondo correlations are dominant and no Andreev bound states localized at the dot are available for Kondo screening. In these conditions superconducting pairing is a competing effect and the junction is $\pi -$like, to optimize antiferromagnetic correlations on the dot. As the superconducting gap increases, the Josephson current also increases, but its phase dependence becomes strongly non sinusoidal.

References in corpus (10)

• Kondo Physics in a Single Electron Transistor
• A Tunable Kondo Effect in Quantum Dots
• Kondo effect in an integer-spin quantum dot
• Phase coherent transport in hybrid superconducting nanostructures
• Enhancement of Kondo effect in quantum dots with an even number of electrons
• Loss of Pi-Junction Behaviour in an Interacting Impurity Josephson Junction
• Tunneling through an Anderson impurity between superconductors
• Spin fractionalization of an even number of electrons in a Quantum dot
• Kondo ground state in a quantum dot with an even number of electrons
• Josephson transport through a Hubbard impurity center

Cited by in corpus (6)

• From four- to two-channel Kondo effect in junctions of XY spin chains
• Tunable Kondo screening length at a Y-junction of three inhomogenous spin chains
• Tunable spin/charge Kondo effect at a double superconducting island connected to two spinless quantum wires
• Junction of three off-critical quantum Ising chains and two-channel Kondo effect in a superconductor
• From Kondo effect to weak-link regime in quantum spin-1/2 spin chains
• Mixed-Valence Transition on a Quantum-Dot Coupled to Superconducting and Spin-Polarized Leads