Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 30: Correlated Electrons: Quantum Impurities, Kondo Physics

TT 30.1: Talk

Tuesday, March 21, 2017, 14:00–14:15, HSZ 03

Renormalized Perturbation Theory as a General Solver for Quantum Impurities — •Simon Jahns and Gertrud Zwicknagl — Institut für Mathematische Physik, TU Braunschweig, Germany

In systems with magnetic impurities conduction electrons are scattered by low energy spin fluctuations leading to the Kondo effect. Due to the strong local electron interactions the low energy scales can not be accessed perturbatively. However, here we are demonstrating the efficiency and flexibility of the RPT [1] as a gerneral impurity solving technique, with which this problem is circumvented.

The central idea is to first determine the renormalized quasiparticle characteristics and to subsequently calculate the Green's functions from a perturbation expansion in terms of the quasiparticle propagators and effective interactions.

The fully renormalized quasiparticle parameters are derived from flow equations connecting a (sometimes hypothetical) weak-coupling regime to the physically relevant strong-couping regime. Typical examples for the flow variable are an external magnetic field or the chemical potential. Results for the single impurity Anderson model (SIAM) have been found in excellent agreement with exact solutions [2].

We discuss the extension of the scheme to more general quantum impurity models accounting to e.g. for Hund's rule correlations.

[1] K. Edwards, A. C. Hewson, J. Phys.: Condens. Matter 23 (2011)

[2] K. Edwards, A. C. Hewson, V. Pandis, Phys. Rev. B 87 (2013)