Scaling picture of magnetism formation in the anomalous f-systems: interplay of the Kondo effect and spin dynamics

TL;DR

This paper investigates the formation of magnetic order in Kondo lattices, analyzing how the interplay of the Kondo effect and spin dynamics influences magnetic phases, critical parameters, and non-Fermi-liquid behavior in heavy-fermion systems.

Contribution

It provides a detailed theoretical analysis of magnetism formation in Kondo lattices, emphasizing the role of spin dynamics and renormalization effects on magnetic and electronic properties.

Findings

Magnetic moments are strongly suppressed only in narrow parameter regions.

Renormalized Kondo temperature shows weak dependence on the bare coupling in ordered phases.

Near magnetic instability, Bose excitation spectra soften, leading to non-Fermi-liquid behavior.

Abstract

Formation of magnetically ordered state in the Kondo lattices is treated within the degenerate $s-f$ exchange and Coqblin-Schrieffer models. The Kondo renormalizations of the effective coupling parameter, magnetic moment and spin excitation frequencies are calculated within perturbation theory. The results of one-loop scaling consideration of the magnetic state in Kondo lattices are analyzed. The dependence of the critical values of the bare model parameters on the type of the magnetic phase and space dimensionality is investigated. Renormalization of the effective Kondo temperature by the interatomic exchange interactions is calculated. An important role of the character of spin dynamics (existence of well-defined magnon excitations, presence of magnetic anisotropy etc.) is demonstrated. The regime of strongly suppressed magnetic moments, which corresponds to magnetic heavy-fermion system, may occur in a rather narrow parameter region only. At the same time, in the magnetically ordered phases the renormalized Kondo temperature depends weakly on the bare coupling parameter in some interval. The critical behavior, corresponding to the magnetic transition with changing the bare $s-f$ coupling parameter, is investigated. In the vicinity of the strong coupling regime, the spectrum of the Bose excitations becomes softened. Thus on the borderline of magnetic instability the Fermi-liquid picture is violated in some temerature interval due to scattering of electrons by these bosons. This may explain the fact that a non-Fermi-liquid behavior often takes place in the heavy-fermion systems near the onset of magnetic ordering.