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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 low-energy 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 single-impurity 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 low-lying quasiparticle excitations for arbitrary values of the bare Hamiltonian's model parameters, we construct an effective low-energy FL Hamiltonian whose FL parameters are expressed in terms of the local level's spin-dependent ground-state 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 V-2 and similar to T-2 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 B-A, B-T, and By at which c(A), c(T), and c(V) change sign, respectively, are all of order T-K, as expected, with B-A = B-T = B-V = 0.75073T(K) in the Kondo limit.