Charge Order in a Two-Dimensional Kondo Lattice Model

TL;DR

This study demonstrates that charge order can occur in a two-dimensional Kondo lattice model without explicit repulsive interactions, revealing its dependence on Kondo coupling and local singlet formation.

Contribution

It provides the first comprehensive numerical evidence of charge order in the 2D Kondo lattice model, clarifying previous controversies.

Findings

Charge order appears at quarter filling in an intermediate Kondo coupling region.

The charge-ordered ground state is an insulator with antiferromagnetic order at charge-poor sites.

Finite temperature charge order is metallic with pseudogap behavior.

Abstract

The possibility of charge order is theoretically examined for the Kondo lattice model in two dimensions, which does not include bare repulsive interactions. Using two complementary numerical methods, we find that charge order appears at quarter filling in an intermediate Kondo coupling region. The charge ordered ground state is an insulator exhibiting an antiferromagnetic order at charge-poor sites, while the paramagnetic charge-ordered state at finite temperatures is metallic with pseudogap behavior. We confirm that the stability of charge order is closely related with the local Kondo-singlet formation at charge-rich sites. Our results settle the controversy on charge order in the Kondo lattice model in realistic spatial dimensions.