Schwinger Boson approach to the fully screened Kondo model

TL;DR

This paper employs the Schwinger boson method to analyze the fully screened Kondo model, capturing the crossover to Fermi liquid behavior and exploring quantum phase transitions in impurity systems.

Contribution

It introduces a generalized Schwinger boson approach that includes antiferromagnetic interactions and describes quantum phase transitions in impurity models.

Findings

Successfully models Kondo crossover to Fermi liquid

Describes quantum phase transition in two impurity system

Captures non-trivial Wilson ratio behavior

Abstract

We apply the Schwinger boson scheme to the fully screened Kondo model and generalize the method to include antiferromagnetic interactions between ions. Our approach captures the Kondo crossover from local moment behavior to a Fermi liquid with a non-trivial Wilson ratio. When applied to the two impurity model, the mean-field theory describes the "Varma Jones" quantum phase transition between a valence bond state and a heavy Fermi liquid.