Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 8: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 8.4: Vortrag
Montag, 7. März 2016, 11:00–11:15, H21
The path Integral formulation of the Schrieffer-Wolff transformation — •Farzaneh Zamani1, Pedro Ribeiro2, and Stefan Kirchner3 — 1Max Planck Institute for the Physics of Complex Systems — 2CeFEMA, Instituto Superior Tecnico, Universidade de Lisboa Avenida Rovisco Pais — 3Center for Correlated Matter, Zhejiang University
The equivalence between the low-energy sector of the Anderson model in the so-called Kondo regime and the spin-isotropic Kondo model is usually established via a canonical transformation performed on the Hamiltonian, followed by a projection. Here, we present a path integral version of this important canonical transformation which relates the functional integral form of the partition function of the Anderson model to that of its effective low-energy model. The resulting functional integral assumes the form of a spin path integral and includes a geometric phase factor, i.e. a Berry phase. Our approach stresses the underlying symmetries of the model and allows for a straightforward generalization of the transformation to more involved models. It thus offers a systematic route of obtaining effective low-energy models and higher order corrections. We demonstrate the effectiveness of our approach by considering the charge Kondo model, and a quantum dot attached to magnetic leads.