Disordered Kondo Nanoclusters: Effect of Energy Spacing

TL;DR

This study uses exact diagonalization to explore how energy spacing influences the magnetic interactions in disordered Kondo nanoclusters, revealing complex phase behavior and the enhancement of local Kondo temperatures due to disorder.

Contribution

It demonstrates the impact of energy spacing and disorder on magnetic regimes and phase diagrams in Kondo nanoclusters, providing insights beyond single-impurity models.

Findings

Tuning energy spacing drives the system between Kondo and RKKY regimes.

Disorder enhances local Kondo temperatures and RKKY interactions.

Complex phase diagram with alternating magnetic order regions.

Abstract

Exact diagonalization results for Kondo nanoclusters alloyed with mixed valence impurities show that tuning the {\it energy spacing}, $\Delta$, drives the system from the Kondo to the RKKY regime. The interplay of $\Delta$ and disorder gives rise to a $\Delta$ versus concentration T=0 phase diagram very rich in structure, where regions with prevailing Kondo or RKKY correlations alternate with domains of ferromagnetic order. The local Kondo temperatures, $T_K$, and RKKY interactions depend strongly on the local environment and are overall {\it enhanced} by disorder, in contrast to the hypothesis of ``Kondo disorder'' single-impurity models.