Doniach phase diagram for Kondo lattice model on the square and triangular lattices

TL;DR

This study explores how geometric frustration influences the Doniach phase diagram in the Kondo lattice model on square and triangular lattices, revealing suppression of antiferromagnetic order and emergence of new magnetic phases.

Contribution

It provides a systematic comparison of the Doniach phase diagram on square and triangular lattices, highlighting the effects of geometric frustration and doping on magnetic order.

Findings

Geometric frustration suppresses AFM order on the triangular lattice.

Doping partially releases frustration, leading to new magnetic orders.

The topology of the Fermi surface influences emergent magnetic phases.

Abstract

Geometric frustration adds a new competing energy scale to the antiferromagnetic (AFM) Kondo lattice model (KLM). In this work, we systematically study the doniach phase diagram on the square and triangular lattices in the same theoretical framework and reveal unexpected responses of it on the two lattices. The potential energy created by the geometric frustration is comparable to the Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling, which completely suppresses the long-range antiferromagnetic (AFM) order on the half-filled triangular lattice. While, on the square lattice, the long-range AFM order successfully establishes and constitutes the conventional competition between the RKKY and Kondo couplings. The geometrical frustration on the triangular lattice is partially released when doped with holes, in which two different magnetic orders emerge unexpectedly. The two orders closely relate to the topology of the interacting Fermi surface. Our comprehensive comparison of the KLM on the two lattices not only reveals a significant competition of geometric frustration, RKKY, and Kondo couplings on low-dimensional systems but also sheds light on experimentally finding new phases in related materials.