A Numerical Renormalization Group Study of a Kondo Hole in a One Dimensional Kondo Insulator

TL;DR

This study uses numerical renormalization group methods to analyze the effects of a Kondo hole in a one-dimensional Kondo insulator, revealing localized midgap states and variations in spin and charge gaps depending on exchange coupling.

Contribution

It provides a detailed numerical analysis of how a Kondo hole affects the electronic and magnetic properties of a 1D Kondo insulator, including gap behaviors and local spin densities.

Findings

Kondo hole introduces midgap states.

Spin density localizes near the hole.

Spin gap and charge gap vary with exchange coupling J.

Abstract

We have studied a Kondo hole in a one-dimensional Kondo insulator at half-filling using a density matrix formulation of the numerical renormalization group. The Kondo hole introduces midgap states. The spin density introduced by the hole is localized in the vicinity of the hole. It resides primarily in the f-spins for small exchange coupling $J$ and in the conduction spins for large $J$. We present results on the spin gap, charge gap, and neutral gap. For small $J$, the spin gap is smaller than the charge gap, while for large $J$, the spin gap is larger than the charge gap. The presence of the Kondo hole reduces RKKY interactions as can be seen in the staggered susceptibility.