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

ALIGIA, A. A.; PABLO ROURA-BAS; BLESIO, GERMÁN; LUIS O. MANUEL

Buenos Aires

Workshop; Workshop on Topological Quantum Matter; 2017

International Center for Advanced Studies, Universidad de San Martin

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 phases close 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. 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 I_L, related with Luttinger theorem, takes in each one of them: I_L = 0 for D < Dc and the non-trivial I_L = pi/2 for D > Dc.