Partial Disorder and Metal-Insulator Transition in the Periodic Anderson Model on a Triangular Lattice

TL;DR

This paper investigates the ground state of the periodic Anderson model on a triangular lattice, revealing two types of partially disordered states and a doping-induced metal-insulator transition.

Contribution

It introduces a systematic mean-field analysis of partial disorder in the model, highlighting the role of lattice geometry and doping in electronic states.

Findings

Identification of two distinct partially disordered states at different fillings

Discovery of a metallic state induced by hole doping due to extended nonmagnetic sites

Explanation of the metal-insulator transition mechanism via electronic structure changes

Abstract

Ground state of the periodic Anderson model on a triangular lattice is systematically investigated by the mean-field approximation. We found that the model exhibits two different types of partially disordered states: one is at half filling and the other is at other commensurate fillings. In the latter case, the kinetic energy is lowered by forming an extensive network involving both magnetic and nonmagnetic sites, in sharp contrast to the former case in which the nonmagnetic sites are rather isolated. This spatially extended nature of nonmagnetic sites yields a metallic partially-disordered state by hole doping. We discuss the mechanism of the metal-insulator transition by the change of electronic structure.