The underscreened Kondo effect in ladder systems

TL;DR

This paper introduces a new Kondo ladder model coupling a S=1 chain with a 1D electron gas, revealing novel low-dimensional spin liquid behaviors and experimental signatures related to the underscreened Kondo effect.

Contribution

It presents a novel Kondo ladder model combining a S=1 chain with an electron gas, providing new insights into underscreened Kondo physics in low-dimensional systems.

Findings

Optical conductivity shows a pseudogap at $k=\pi$ despite insulating state.

Coexistence of a coherent magnon peak with an incoherent spinon background.

Magnetization exhibits fractional-like quantization.

Abstract

We introduce a new Kondo ladder model by coupling the well-known Takhtajan-Babujan S=1 chain to a half-filled one-dimensional electron gas, and we solve it using quantum field theory techniques. Through the so-called underscreened Kondo effect, this gives novel insights into low-dimensional spin liquid systems. For instance, the optical conductivity reveals only a pseudogap at $k=\pi$ despite of the insulating state, a coherent magnon peak in the dynamical spin susceptibility coexists with an incoherent spinon background, the magnetization yields a fractional-like quantization. More generally, this problem belongs to the class of Luttinger liquids in active environments, a topic of importance not only to the Kondo physics, but also to striped phases or carbon nanotubes. Experimental consequences on heavy-fermion systems are also discussed.