Fermi Liquid Theory for the Nonequilibrium Kondo Effect at Low Bias Voltages(<SPECIAL TOPICS>Kondo Effect-40 Years after the Discovery)

概要

論文の詳細を見る
In this paper, we describe a recent development in a Fermi liquid theory for the Kondo effect in quantum dots under a finite bias voltage V. Applying the microscopic theory of Yamada and Yosida to a nonequilibrium steady state, we derive the Ward identities for the Keldysh Green's function, and determine the low-energy behavior of the differential conductance dI/dV exactly up to terms of order (eV)^2 for the symmetric Anderson model. These results are deduced from the fact that the Green's function at the impurity site is a functional of a nonequilibrium distribution f_<eff>(ω), which at eV=0 coincides with the Fermi function. Furthermore, we provide an alternative description of the low-energy properties using a renormalized perturbation theory (RPT). In the nonequilibrium state the unperturbed part of the RPT is determined by the renormalized free quasiparticles, the distribution function of which is given by f_<eff>(ω). The residual interaction between the quasiparticles U^^∿, which is defined by the full vertex part at zero frequencies, is taken into account by an expansion in the power series of U^^∿. We also discuss the application of the RPT to a high-bias region beyond the Fermi-liquid regime.
社団法人日本物理学会の論文
2005-01-15