Filippone, Michele; Moca, Catalin Pascu; Weichselbaum, Andreas; Delft, Jan von; Mora, Christophe
(2018):
At which magnetic field, exactly, does the Kondo resonance begin to split? A Fermi liquid description of the lowenergy properties of the Anderson model.
In: Physical Review B, Vol. 98, No. 7, 75404

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Abstract
This paper is a corrected version of Phys. Rev. B 95, 165404 (2017), which we have retracted because it contained a trivial but fatal sign error that lead to incorrect conclusions. We extend a recently developed Fermi liquid (FL) theory for the asymmetric singleimpurity Anderson model [C. Mora et al., Phys. Rev. B 92, 075120 (2015)] to the case of an arbitrary local magnetic field. To describe the system's lowlying quasiparticle excitations for arbitrary values of the bare Hamiltonian's model parameters, we construct an effective lowenergy FL Hamiltonian whose FL parameters are expressed in terms of the local level's spindependent groundstate occupations and their derivatives with respect to level energy and local magnetic field. These quantities are calculable with excellent accuracy from the Bethe ansatz solution of the Anderson model. Applying this effective model to a quantum dot in a nonequilibrium setting, we obtain exact results for the curvature of the spectral function, c(A), describing its leading similar to epsilon(2) term, and the transport coefficients c(V) and c(T), describing the leading similar to V2 and similar to T2 terms in the nonlinear differential conductance. A sign change in c(A) or c(V) is indicative of a change from a local maximum to a local minimum in the spectral function or nonlinear conductance, respectively, as is expected to occur when an increasing magnetic field causes the Kondo resonance to split into two subpeaks. We find that the fields BA, BT, and By at which c(A), c(T), and c(V) change sign, respectively, are all of order TK, as expected, with BA = BT = BV = 0.75073T(K) in the Kondo limit.