Spectral density of an interacting dot coupled indirectly to conducting leads

Abstract

We study the spectral density of electrons rho in an interacting quantum dot (QD) with a hybridization lambda to a non-interacting QD, which in turn is coupled to a non-interacting conduction band. The system corresponds to an impurity Anderson model in which the conduction band has a Lorentzian density of states of width Delta2. 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 Delta2 -> 0. For fixed U and large enough lambda or small enough Delta2, the Kondo peak in rho(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 Delta2, the side bands of rho(omega) have the form of narrow resonances, that were missed in previous studies using the numerical renormalization group. This technique also has shortcomings for describing properly 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.

13 pages, 13 figures, accepted in Phys. Rev. B

References in corpus (6)

• Strongly correlated regimes in a double quantum-dot device
• Zero-field Kondo splitting and quantum-critical transition in double quantum dots
• Nonequilibrium magnetotransport through a quantum dot: An interpolative perturbative approach
• Conductance through an array of quantum dots
• Spin-charge separation and simultaneous spin and charge Kondo effect
• Spectral densities of Kondo impurities in nanoscopic systems

Cited by in corpus (11)

• Perfect spin polarization in T-shaped double quantum dots due to the spin-dependent Fano effect
• Thermopower of an SU(4) Kondo resonance under an SU(2) symmetry-breaking field
• Universal scaling in nonequilibrium transport through an Anderson impurity
• Full electrostatic control over polarized currents through spin-orbital Kondo effect
• Features of spin-charge separation in the equilibrium conductance through finite rings
• Width of the charge-transfer peak in the SU(N) impurity Anderson model and its relevance to non-equilibrium transport
• Scanning tunneling microscopy of adsorbed molecules on metalic surfaces for nearly localized atomic states
• Photoluminiscence of a quantum dot hybridized with a continuum
• Kondo temperature when the Fermi level is near a step in the conduction density of states
• Zero-field splitting of the Kondo resonance and quantum criticality in triple quantum dots
• Kondo physics of magnetic adatoms on metallic surfaces when the onset of the surface conduction density of states crosses the Fermi level