Spin fluctuations of a random vacuum state: a new approach to the Kondo lattice

TL;DR

This paper introduces a novel approach to the Kondo lattice by representing local moments as spin fluctuations, leading to the discovery of new fermionic modes and complex excitation spectra.

Contribution

It presents a new representation of local moments as spin fluctuations, resulting in a novel analysis of the excitation spectrum in the Kondo lattice.

Findings

Identification of two doublet bands and one quadruplet in the excitation spectrum.

One doublet closely resembles the original electronic band at low exchange coupling.

Other bands exhibit large effective masses due to coherent recombinations.

Abstract

We address the Kondo lattice with one conduction band by introducing a representation of the (s=1/2) local moments consisting in an s=1 triplet of spin fluctuations of a vacuum state. The excitation of these fluctuations by the electronic field results in the creation of new fermionic modes. It is shown that, in the one-electron case, the zero-temperature spectrum of these excitations consists in two s=1/2 doublet bands and an s=3/2 quadruplet. One of the doublets is seen to be a slight modification of the bare initial electronic band for low values of the exchange coupling, while the other bands correspond to complex, coherent recombinations of the bare electron and spin fluctuations displaying large effective masses.