Anderson model out of equilibrium: Decoherence effects in transport through a quantum dot

作者：Van Roermund Raphael^*; Shiau Shiue yuan; Lavagna Mireille

来源：Physical Review B, 2010, 81(16): 165115.

DOI：10.1103/PhysRevB.81.165115

The paper deals with the nonequilibrium two-lead Anderson model, considered as an adequate description for transport through a dc biased quantum dot. Using a self-consistent equation-of-motion method generalized out of equilibrium, we calculate a fourth-order decoherence rate gamma(4) induced by a bias voltage V. This decoherence rate provides a cutoff to the infrared divergences of the self-energy showing up in the Kondo regime. At low temperature, the Kondo peak in the density of states is split into two peaks pinned at the chemical potential of the two leads. The height of these peaks is controlled by gamma((4)). The voltage dependence of the differential conductance exhibits a zero-bias peak followed by a broad Coulomb peak at large V, reflecting charge fluctuations inside the dot. The low-bias differential conductance is found to be a universal function of the normalized bias voltage V/T(K), where T(K) is the Kondo temperature of the model, which has been improved in comparison with previous approaches. The universal scaling with a single energy scale T(K) at low-bias voltages is also observed for the renormalized decoherence rate gamma((4))/T(K). We discuss the effect of gamma((4)) on the crossover from strong- to weak-coupling regime when either the temperature or the bias voltage is increased.

• 出版日期2010-4-15