Topological quantum phase transition between two Fermi liquid ground states through a non-Fermi liquid in a generalized Anderson impurity model

BLESIO, G.G.; ALIGIA, A. A.; ROURA-BAS, P.; MANUEL, L.O.

Foz de Iguazú

Congreso; Autumn Meeting of the Brazilian Physical Society; 2018

The Brazilian Physical Society

Quantum phase transitions build up one of the scenarios for the emergence of non-Fermi liquid (NFL) behavior in electronic systems, driven by the strong competence between quantum fluctuations of the two distinct phasesclose to the critical point. In this work, we solve a S=1 Anderson impurity model with single-ion anisotropy D, coupled to two degenerate conduction bands, using the numerical renormalization group (NRG). The model has been derived for a single Ni impurity embedded into an O-doped Au chain. At a critical anisotropy Dc > 0, we find a quantum phase transition between two regular Fermi liquid phases: for D < Dc the impurity is Kondo screened, while, for D > Dc , the impurity magnetic degree of freedom is quenched by the anisotropy. Surprisingly, the Fermi liquids are separated by a NFL region, whose behavior corresponds to a two-channel Kondo effect, as we have been able to characterize it through an analysis of entropy and electrical conductance. In addition, the two Fermi liquids are differentiated topologically by the value that the integral IL , related with Luttinger theorem, takes in each one of them: IL = 0 for D < Dc and the non-trivial IL = −π/2 for D > Dc.