Spin, Charge and Quasiparticle Gaps in the One-Dimensional Kondo Lattice with f^2 Configuration

TL;DR

This study investigates the ground state properties of a one-dimensional Kondo lattice with f^2 configuration, revealing how competition between exchange interactions affects energy gaps, local correlations, and potential metal-insulator transitions.

Contribution

It provides new insights into the effects of exchange competition on energy gaps and local correlations in the f^2 Kondo lattice using DMRG methods.

Findings

Energy gaps decrease due to exchange competition.

Bound states form among conduction electrons.

Transition from itinerant to localized spin-1/2 excitations.

Abstract

The ground state properties of the one-dimensional Kondo lattice with an f^2 configuration at each site are studied by the density matrix renormalization group method. At half-filling, competition between the Kondo exchange J and the antiferromagnetic intra f-shell exchange I leads to reduction of energy gaps for spin, quasi-particle and charge excitations. The attractive force among conduction electrons is induced by the competition and the bound state is formed. As J/I increases the f^2 singlet gives way to the Kondo singlet as the dominant local correlation. The remarkable change of the quasi-particle gap is driven by the change of the spin-1/2 excitation character from the itinerant one to the localized one. Possible metal-insulator transition is discussed which may occur as the ratio J/I is varied by reference to mean-field results in the f^2 lattice system and the two impurity Kondo system.