Partial Disorder in the Periodic Anderson Model on a Triangular Lattice

TL;DR

This paper theoretically investigates a partially-disordered state in the periodic Anderson model on a triangular lattice, revealing coexistence of magnetic and nonmagnetic sites, charge gap opening, and a unique low-energy spectrum crossover.

Contribution

It demonstrates the emergence of a partially-disordered state in the periodic Anderson model without spin anisotropy, contrasting previous findings in the Kondo lattice model.

Findings

Partially-disordered state characterized by magnetic and nonmagnetic coexistence.

Charge gap opens between magnetic metal and Kondo insulator.

Distinct low-energy excitation spectrum crossover observed.

Abstract

We report our theoretical results on the emergence of a partially-disordered state at zero temperature and its detailed nature in the periodic Anderson model on a triangular lattice at half filling. The partially-disordered state is characterized by coexistence of a collinear antiferromagnetic order on an unfrustrated honeycomb subnetwork and nonmagnetic state at the remaining sites. This state appears with opening a charge gap between a noncollinear antiferromagnetic metal and Kondo insulator while changing the hybridization and Coulomb repulsion. We also find a characteristic crossover in the low-energy excitation spectrum as a result of coexistence of magnetic order and nonmagnetic sites. The result demonstrates that the partially-disordered state is observed distinctly even in the absence of spin anisotropy, in marked contrast to the partial Kondo screening state found in the previous study for the Kondo lattice model.