Dynamic Spin Correlation Function near the Antiferromagnetic Quantum Phase Transition of Heavy-Fermions

TL;DR

This paper investigates the dynamical spin susceptibility near the antiferromagnetic quantum phase transition in heavy-Fermion systems, revealing a two-component behavior consistent with experimental neutron scattering data.

Contribution

It introduces a perturbative expansion within the $S=1/2$ Kondo lattice model that captures both Fermi liquid and non-Fermi liquid features near the transition.

Findings

Identification of a two-component dynamical spin susceptibility

Inelastic peak shifts to zero at the transition point

Agreement with neutron scattering experimental results

Abstract

The dynamical spin susceptibility is studied in the magnetically-disordered phase of heavy-Fermion systems near the antiferromagnetic quantum phase transition. In the framework of the $S=1/2$ Kondo lattice model, we introduce a perturbative expansion treating the spin and Kondo-like degrees of freedom on an equal footing. The dynamical spin susceptibility displays a two-component behaviour in agreement with the inelastic neutron scattering (INS) experiments performed in $CeCu_{6}$, $Ce_{1-x}La_{x}Ru_{2}Si_{2}$ and $UPt_{3}$: a quasielastic q-independent peak as in a Fermi liquid theory, and a strongly q-dependent inelastic peak typical of a non-Fermi liquid behaviour. Very strikingly, the position of the inelastic peak is found to be pushed to zero at the antiferromagnetic transition. The picture is consistent with the neutron cross sections observed in INS experiments.