Quantum Monte Carlo simulations of the half-filled two-dimensional Kondo lattice model

TL;DR

This paper uses quantum Monte Carlo simulations to study the phase transition in the half-filled 2D Kondo lattice model, revealing a continuous transition between antiferromagnetic and spin-gapped insulating phases at a specific coupling ratio.

Contribution

It demonstrates the applicability of efficient auxiliary field Monte Carlo methods to the 2D Kondo lattice model and characterizes the quantum phase transition between magnetic and non-magnetic phases.

Findings

Identified the critical coupling J/t = 1.45 1 0.05 for the phase transition.

Computed the staggered magnetic moment and energy gaps on 12x12 lattices.

Established the continuous nature of the quantum phase transition.

Abstract

The 2D half-filled Kondo lattice model with exchange J and nearest neighbor hopping t is considered. It is shown that this model belongs to a class of Hamiltonians for which zero-temperature auxiliary field Monte Carlo methods may be efficiently applied. We compute the staggered moment, spin and quasiparticle gaps on lattice sizes up to 12 X 12. The competition between the RKKY interaction and Kondo effect leads to a continuous quantum phase transition between antiferromagnetic and spin-gaped insulators. This transition occurs at J/t = 1.45 \pm 0.05.