Anderson model out of equilibrium: Noncrossing-approximation approach to transport through a quantum dot

Ned S. Wingreen

NEC Research Institute, 4 Independence Way, Princeton, New Jersey 08540

Yigal Meir

Department of Physics, University of California, Santa Barbara, California 93106

(Received 28 September 1993)

The infinite-U Anderson model is applied to transport through a quantum dot. The current and density of states are obtained via the noncrossing approximation for two spin-degenerate levels weakly coupled to two leads. At low temperatures, the Kondo peak in the equilibrium density of states strongly enhances the linear-response conductance. Application of a finite voltage bias reduces the conductance and splits the peak in the density of states. The split peaks, one at each chemical potential, are suppressed in amplitude by a finite dissipative lifetime. We estimate this lifetime perturbatively as the time to transfer an electron from the higher-chemical-potential lead to the lower-chemical-potential one. At zero magnetic field, the clearest signatures of the Kondo effect in transport through a quantum dot are the broadening, shift, and enhancement of the linear-response conductance peaks at low temperatures, and a peak in the nonlinear differential conductance around zero bias.

©1994 The American Physical Society.

PACS: 72.15.Qm 73.20.Dx 73.40.Gk 73.50.Fq

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