Spectral density of an interacting dot coupled indirectly to conducting leads

Article

关键词: NUMERICAL RENORMALIZATION-GROUP;    SINGLE-ELECTRON TRANSISTOR;    ANDERSON MODEL;    PERTURBATION EXPANSION;    IMPURITY STATES;    QUANTUM DOTS;    TRANSPORT;    MIRAGES;    ENERGY;   

DOI  :  10.1103/PhysRevB.76.165112

来源: SCIE

【 摘 要 】

We study the spectral density of electrons rho(d sigma)(omega) in an interacting quantum dot (QD) with a hybridization lambda to a noninteracting QD, which, in turn, is coupled to a noninteracting conduction band. The system corresponds to an impurity Anderson model in which the conduction band has a Lorentzian density of states of width Delta(2). We solved the model using perturbation theory in the Coulomb repulsion U (PTU) up to second order and a slave-boson mean-field approximation (SBMFA). The PTU works surprisingly well near the exactly solvable limit Delta(2)-> 0. For fixed U and large enough lambda or small enough Delta(2), the Kondo peak in rho(d sigma)(omega) splits into two peaks. This splitting can be understood in terms of weakly interacting quasiparticles. Before the splitting takes place, the universal properties of the model in the Kondo regime are lost. Using the SBMFA, simple analytical expressions for the occurrence of split peaks are obtained. For small or moderate Delta(2), the side bands of rho(d sigma)(omega) have the form of narrow resonances that were missed in previous studies using the numerical renormalization group. This technique also has shortcomings for properly describing the split Kondo peaks. As the temperature is increased, the intensity of the split Kondo peaks decreases, but it is not completely suppressed at high temperatures.

【 授权许可】

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