Nonlinear Sigma Model Analysis of the AFM Phase Transition of the Kondo Lattice

TL;DR

This paper investigates the quantum phase transition in a 2D Kondo-Heisenberg lattice using a non-linear sigma model, revealing a new quantum critical point dominated by Kondo fluctuations and proposing an updated phase diagram.

Contribution

The study introduces a renormalization group analysis of the AFM transition in a 2D Kondo lattice, identifying a novel quantum critical point influenced by Kondo effects.

Findings

Discovery of a new quantum critical point dominated by Kondo fluctuations

Logarithmic scaling of spin-wave velocity near the QCP

Proposal of an updated phase diagram for the 2D Kondo lattice

Abstract

We have studied the antiferromagnetic quantum phase transition of a 2D Kondo-Heisenberg square lattice using the non-linear sigma model. A renormalization group analysis of the competing Kondo -- RKKY interaction was carried out to 1-loop order in the $\epsilon$ expansion, and a new quantum critical point is found, dominated by Kondo fluctuations. In addition, the spin-wave velocity scales logarithmically near the new QCP, i.e breakdown of hydrodynamic behavior. The results allow us to propose a new phase diagram near the AFM fixed point of this 2D Kondo lattice model.