Hole doping and weak quenched disorder effects on the 1D Kondo lattice for ferromagnetic Kondo couplings

TL;DR

This paper explores how hole doping and weak quenched disorder influence the properties of the one-dimensional ferromagnetic Kondo lattice model, revealing conditions for insulator states and the impact of disorder on localization.

Contribution

It introduces a bosonization analysis of the 1D Kondo lattice with ferromagnetic couplings, identifying new insulator phases and disorder effects using renormalization group methods.

Findings

Small hole doping induces charge sector masslessness.

Disorder suppresses Anderson localization only at strong ferromagnetic couplings.

Identifies ferromagnetic spin ladder and S=1 antiferromagnet as new insulators.

Abstract

We investigate the one-dimensional Kondo lattice model (1D KLM) for ferromagnetic Kondo couplings, by using the bosonization method. The ferromagnet ic 2-leg spin ladder and the S=1 antiferromagnet occur as new one-dimensional Kondo insulators, for a half-filled band. First,a very small hole-doping makes the charge sector massless and it can produce, either an incommensurate RKKY interaction or a S=1 ferromagnet according to the strength of the ferromagnetic Kondo coupling. Second, we investigate, the effects of a weak and quenched disorder on these two Kondo insulators, by applying renormalization group methods: the Anderson localization is suppressed only in the context of a strong ferromagnetic Kondo coupling.