Out-of-Equilibrium Anderson Model at High and Low Bias Voltages(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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We study the high-and low-voltage properties of the out-of-equilibrium Anderson model for quantum dots, using a functional method in the Keldysh formalism. The Green's function at the impurity site can be regarded as a functional of a nonequilibrium distribution function &inof;_eff(ω). The dependence of the Green's function on the bias voltage V and temperature T arises through &inof;_eff(ω). From this behavior as a functional,it is shown that the nonequilibrium Green's function at eV → ∞ is identical to the equilibrium one at T → ∞. This correspondence holds when the couplings of the dot and two leads, at the left and right, are equal. In the opposite limit, for small eV, the low-energy behavior of the Green's function can be described by the local Fermi-liquid theory up to terms of order (eV)^2. These results imply that the correlation effects due to the Coulomb interaction U can be treated adiabatically in the two limits, at high and low bias voltages.
社団法人日本物理学会の論文
2002-12-15