Kondo crossover in shot noise of a single quantum dot with orbital degeneracy

Article

关键词: FERMI-LIQUID THEORY;    LOW-BIAS VOLTAGES;    ANDERSON MODEL;    RENORMALIZATION-GROUP;    QUASI-PARTICLE;    IMPURITY;    EQUILIBRIUM;    EXPANSION;    FIELD;   

DOI  :  10.1103/PhysRevB.83.075440

来源: SCIE

【 摘 要 】

We investigate out-of-equilibrium transport through an orbital Kondo system realized in a single quantum dot, described by the multiorbital impurity Anderson model. Shot noise and current are calculated up to the third order in bias voltage in the particle-hole symmetric case, using the renormalized perturbation theory. The derived expressions are asymptotically exact at low energies. The resulting Fano factor of the backscattering current F-b is expressed in terms of the Wilson ratio R and the orbital degeneracy N as F-b = 1+9(N-1)(R-1)(2)/1+5(N-1)(R-1)(2) at zero temperature. Then, for small Coulomb repulsions U, we calculate the Fano factor exactly up to terms of order U-5, and also carry out the numerical renormalization group calculation for intermediate U in the case of twofold and fourfold degeneracy (N = 2, 4). As U increases, the charge fluctuation in the dot is suppressed, and the Fano factor varies rapidly from the noninteracting value F-b = 1 to the value in the Kondo limit F-b = N+8/N+4, near the crossover region U similar to pi Gamma, with the energy scale of the hybridization Gamma.

【 授权许可】

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