Crossover from dilute-Kondo system to heavy-fermion system

TL;DR

This paper investigates the transition from dilute-Kondo to heavy-fermion systems in a Kondo lattice model, revealing how electron densities influence the crossover and the nature of Kondo screening.

Contribution

It demonstrates the crossover point when $n_f$ becomes comparable to $n_c$ and characterizes the change from individual to collective Kondo screening.

Findings

Crossover occurs at $n_f \,\lesssim\, n_c$

Strong $f$-$f$ electron correlations in heavy-fermion phase

Shift from individual to collective Kondo screening

Abstract

Ground state properties of a Kondo lattice model with random configuration of $f$ electrons are investigated with a variational Monte Carlo method. We show that the crossover from a dilute-Kondo system to a heavy-fermion system occurs when the density of $c$ and $f$ electrons ($n_c$, $n_f$) become comparable, $n_f\lesssim n_c$. In the heavy-fermion region, the correlation between $f$ electrons is strong and the $f$ electrons themselves greatly contribute to the screening of other $f$-electron moments. We propose that the character of Kondo screening changes from "individual" to "collective" across the crossover.