Nonequilibrium Kondo Effect in a Multi-level Quantum Dot near singlet-triplet transition

Abstract

The linear and nonlinear transport through a multi-level lateral quantum dot connected to two leads is investigated using a generalized finite-$U$ slave-boson mean field approach. For a two-level quantum dot, our calculation demonstrates a substantial conductance enhancement near the degeneracy point of the spin singlet and triplet states, a non-monotonic temperature-dependence of conductance and a sharp dip and nonzero bias maximum of the differential conductance. These agree well with recent experiment observations. This two-stage Kondo effect in an out-of-equilibrium situation is attributed to the interference between the two energy levels.

4 pages, 3 figures

References in corpus (7)

• Kondo effect in real quantum dots
• Two-stage Kondo effect in a quantum dot at high magnetic field
• Quantum Phase Transition in a Multi-Level Dot
• Quantum phase transitions in models of coupled magnetic impurities
• Kondo effect induced by a magnetic field
• Kondo effect and anti-ferromagnetic correlation in transport through tunneling-coupled double quantum dots
• Mean Field Theory of the Kondo Effect in Quantum Dots with an Even Number of Electrons

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• SU(4) versus SU(2) Kondo effect in double quantum dot
• The $SU(4)-SU(2)$ crossover and spin filter properties of a double quantum dot nanosystem
• Thermal Symmetry Crossover and Universal Behaviors in Carbon Nanotube Dots
• Enhanced spin injection efficiency in a four-terminal double quantum dot system
• Universal conductance enhancement and reduction of the two-orbital Kondo effect