Electron transport in the four-lead two-impurity Kondo model: Nonequilibrium perturbation theory with almost degenerate levels

Abstract

The eigenstates of an isolated nanostructure may get mixed by the coupling to external leads. This effect is the stronger, the smaller the level splitting on the dot and the larger the broadening induced by the coupling to the leads. We describe how to calculate the nondiagonal density matrix of the nanostructure efficiently in the cotunneling regime. As an example, we consider a system of two quantum dots in the Kondo regime, the two spins coupled by an antiferromagnetic exchange interaction and each dot tunnel coupled to two leads. Calculating the nonequilibrium density matrix and the corresponding current, we demonstrate the importance of the off-diagonal terms in the presence of an applied magnetic field and a finite bias voltage.

10 pages, 8 figures

References in corpus (7)

• Spin qubits with electrically gated polyoxometalate molecules
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• Detection of Single Spin Decoherence in a Quantum Dot via Charge Currents
• Nonequilibrium Transport through a Kondo Dot in a Magnetic Field: Perturbation Theory
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Cited by in corpus (6)

• Resonant and Kondo tunneling through molecular magnets
• Transport through a Kondo quantum dot: Functional RG approach
• Inelastic cotunneling in quantum dots and molecules with weakly broken degeneracies
• Exchange cotunneling through quantum dots with spin-orbit coupling
• Interplay between interference and Coulomb interaction in the ferromagnetic Anderson model with applied magnetic field
• Nonequilibrium Cotunneling through a Three-Level Quantum Dot