Fermi Surface and Magnetism in the Kondo lattice: A Continuum Field Theory Approach

TL;DR

This paper develops a continuum field theory to analyze the Fermi surface and magnetic phases in the Kondo lattice, revealing a distinct antiferromagnetic phase with a small Fermi surface where local moments do not contribute to Fermi-surface formation.

Contribution

It introduces a new theoretical framework for understanding the small Fermi surface phase in the Kondo lattice, extending previous work to cases with Fermi surface intersections with the Brillouin zone boundary.

Findings

Existence of an AF_S phase with a small Fermi surface.

Contrasts the AF_S phase with the conventional large Fermi surface assumption.

Highlights the importance of dynamical screening processes in the AF_S phase.

Abstract

We consider the Fermi surface inside the antiferromagnetic ordered region of a Kondo lattice system in an arbitrary dimension higher than one. We establish the existence of ${\rm AF_S}$, an antiferromagnetic phase whose Fermi surface is ``small,'' in the sense that the local moments do not participate in the Fermi-surface formation. This is in contrast to the ``large'' Fermi surface that is typically assumed for heavy fermion metals. We extend our earlier work to the case that the Fermi surface of the conduction electrons intersects the antiferromagnetic Brillouin zone boundary. Our results provide a new perspective on local quantum criticality. In addition, our results imply that, for the ${\rm AF_S}$ phase, it is important to keep track of the dynamical screening processes; we suggest that this effect is not captured in a recent variational Monte-Carlo study of the Kondo lattice.