TY - JOUR

T1 - Mean-field theory of the Kondo effect in quantum dots with an even number of electrons

AU - Eto, Mikio

AU - Nazarov, Yuli V.

N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.

PY - 2001

Y1 - 2001

N2 - We investigate the enhancement of the Kondo effect in quantum dots with an even number of electrons, using a scaling method and a mean field theory. We evaluate the Kondo temperature (formula presented) as a function of the energy difference between spin-singlet and -triplet states in the dot, (formula presented) and the Zeeman splitting, (formula presented) If the Zeeman splitting is small, (formula presented) the competition between the singlet and triplet states enhances the Kondo effect. (formula presented) reaches its maximum around (formula presented) and decreases with (formula presented) obeying a power law. If the Zeeman splitting is strong, (formula presented) the Kondo effect originates from the degeneracy between the singlet state and one of the components of the triplet state at (formula presented) We show that (formula presented) exhibits another power-law dependence on (formula presented) The mean field theory provides a unified picture to illustrate the crossover between these regimes. The enhancement of the Kondo effect can be understood in terms of the overlap between the Kondo resonant states created around the Fermi level. These resonant states provide the unitary limit of the conductance (formula presented)

AB - We investigate the enhancement of the Kondo effect in quantum dots with an even number of electrons, using a scaling method and a mean field theory. We evaluate the Kondo temperature (formula presented) as a function of the energy difference between spin-singlet and -triplet states in the dot, (formula presented) and the Zeeman splitting, (formula presented) If the Zeeman splitting is small, (formula presented) the competition between the singlet and triplet states enhances the Kondo effect. (formula presented) reaches its maximum around (formula presented) and decreases with (formula presented) obeying a power law. If the Zeeman splitting is strong, (formula presented) the Kondo effect originates from the degeneracy between the singlet state and one of the components of the triplet state at (formula presented) We show that (formula presented) exhibits another power-law dependence on (formula presented) The mean field theory provides a unified picture to illustrate the crossover between these regimes. The enhancement of the Kondo effect can be understood in terms of the overlap between the Kondo resonant states created around the Fermi level. These resonant states provide the unitary limit of the conductance (formula presented)

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U2 - 10.1103/PhysRevB.64.085322

DO - 10.1103/PhysRevB.64.085322

M3 - Article

AN - SCOPUS:0035880970

VL - 64

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 8

ER -