New results about the one dimensional Kondo lattice model

TL;DR

This paper explores the one-dimensional Kondo lattice model by including a direct exchange term, revealing conditions for a heavy-fermion phase or a Tomonaga-Luttinger liquid using non-Abelian bosonization.

Contribution

It introduces a direct exchange term into the 1D Kondo lattice model and analyzes its effects on the ground state phases using non-Abelian bosonization.

Findings

A coherent heavy-fermion phase is stabilized when the direct exchange exceeds the RKKY interaction.

When the direct exchange is less than the RKKY interaction, the system behaves as a Tomonaga-Luttinger liquid.

The phase diagram depends on the relative strength of the direct exchange and the RKKY interaction.

Abstract

The one-dimensional Kondo lattice model (1D KLM) is usually defined by the Kondo exchange $J$ between conduction electrons and spins of the array, and the hopping strength t for the moving electrons. Here, we also include a direct exchange $K$ term between spins of the lattice, and we investigate situations where the bare value of $K$ does not exceed $J$. By using the non-Abelian bosonization, we show that a coherent heavy-fermion phase can be stabilized, when the bare value of $K$ exceeds the RKKY exchange (ruled by $T_A\simeq J^2/t$). Conversely, when $K<T_A$, the low-energy fixed point is rather a Tomonaga-Luttinger (TL) liquid.