Multi-Channel Kondo Necklace

TL;DR

This paper introduces a multi-channel Kondo necklace model to explore overscreened Kondo lattice features, analyzing its phase diagram and critical temperature behavior using mean-field approximation.

Contribution

It formulates a simplified multi-channel Kondo model with permutation symmetry, revealing how Kondo coupling influences phase transitions and critical temperatures.

Findings

Critical temperature increases with Kondo interaction for N>2

Kondo coupling leads to composite pseudospin ordering

Model captures features of overscreened Kondo lattice

Abstract

A multi--channel generalization of Doniach's Kondo necklace model is formulated, and its phase diagram studied in the mean--field approximation. Our intention is to introduce the possible simplest model which displays some of the features expected from the overscreened Kondo lattice. The $N$ conduction electron channels are represented by $N$ sets of pseudospins $\vt_{j}$, $j=1, ... , N$, which are all antiferromagnetically coupled to a periodic array of $|\vs|=1/2$ spins. Exploiting permutation symmetry in the channel index $j$ allows us to write down the self--consistency equation for general $N$. For $N>2$, we find that the critical temperature is rising with increasing Kondo interaction; we interpret this effect by pointing out that the Kondo coupling creates the composite pseudospin objects which undergo an ordering transition. The relevance of our findings to the underlying fermionic multi--channel problem is discussed.