Antiferromagnetism versus Kondo screening in the two-dimensional periodic Anderson model at half filling: Variational cluster approach

TL;DR

This paper uses the variational cluster approach to study the competition between antiferromagnetism and Kondo screening in a two-dimensional periodic Anderson model, identifying phase transitions and critical interaction strengths.

Contribution

It demonstrates that VCA can quantitatively describe the phase transition between antiferromagnetic and Kondo insulating states in the model.

Findings

Antiferromagnetic order occurs in the strong coupling regime.

Kondo insulating state exists without symmetry breaking in the weak coupling regime.

Critical interaction strength for phase transition is estimated.

Abstract

The variational cluster approach (VCA) based on the self-energy functional theory is applied to the two-dimensional symmetric periodic Anderson model at half filling. We calculate a variety of physical quantities including the staggered moments and single-particle spectra at zero temperature to show that the symmetry breaking due to antiferromagnetic ordering occurs in the strong coupling region, whereas in the weak coupling region, the Kondo insulating state without symmetry breaking is realized. The critical interaction strength is estimated. We thus demonstrate that the phase transition due to competition between antiferromagnetism and Kondo screening in the model can be described quantitatively by VCA.