Antiferromagnetic Phases of the Kondo Lattice

TL;DR

This paper explores the different antiferromagnetic phases of the 2D Kondo lattice, revealing two distinct solutions with different Fermi surface characteristics and phase transitions, aligning qualitatively with experimental observations.

Contribution

It introduces a bond Fermion approach to analyze the Kondo lattice, identifying two antiferromagnetic phases and their phase transitions, which enhances understanding of heavy fermion systems.

Findings

Two antiferromagnetic solutions with distinct Fermi surfaces

First and second order phase transitions between phases

Qualitative agreement with experiments on CeRh(1-x)Co(x)In(5)

Abstract

We discuss the paramagnetic and Neel-ordered phases of the Kondo lattice Hamiltonian on the 2D square lattice by means of bond Fermions. In the doped case we find two antiferromagnetic solutions, the first one with small ordered moment, heavy bands, and an antiferromagetically folded large Fermi surface - i.e. including the localized spins - the second one with large ordered moment, light bands and an antiferromagnetically folded conduction electron-only Fermi surface. The zero temperature phase diagram as a function of Kondo coupling and conduction electron density shows first and second order transition lines between the three different phases and agrees qualitatively with previous numerical studies. We compare to experiments on CeRh(1-x)Co(x)In(5) and find qualitative agreement.