Nonlinear Fermi liquid transport through a quantum dot in asymmetric tunnel junctions

Article

关键词: RENORMALIZATION-GROUP;    PERTURBATION EXPANSION;    KONDO;    IMPURITY;    SYSTEMS;   

DOI  :  10.1103/PhysRevB.104.235147

来源: SCIE

【 摘 要 】

We study the nonlinear conductance through a quantum dot, specifically its dependence on the asymmetries in the tunnel couplings and bias voltages V, at low energies. Extending the microscopic Fermi liquid theory for the Anderson impurity model, we obtain an exact formula for the steady current I up to terms of order V3 in the presence of these asymmetries. The coefficients for the nonlinear terms are described in terms of a set of the Fermi liquid parameters: the phase shift, static susceptibilities, and three-body correlation functions of electrons in the quantum dots, defined with respect to the equilibrium ground state. We calculate these correlation functions, using the numerical renormalization group approach (NRG), over a wide range of impurity-electron filling that can be controlled by a gate voltage in real systems. The NRG results show that the order V2 nonlinear current is enhanced significantly in the valence fluctuation regime. It is caused by the order V energy shift of the impurity level, induced in the presence of the tunneling or bias asymmetry. Furthermore, in the valence fluctuation regime, we also find that the order V3 nonlinear current exhibits a shoulder structure, for which the three-body correlations that evolve for large asymmetries play an essential role.

【 授权许可】

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