Disorder, inhomogeneity and spin dynamics in f-electron non-Fermi liquid systems

TL;DR

This paper investigates how structural disorder influences spin dynamics in f-electron non-Fermi-liquid systems, highlighting the limitations of local disorder theories and emphasizing the role of cooperative spin fluctuations.

Contribution

It provides experimental evidence linking disorder to spin dynamics and challenges local disorder models by showing the importance of critical spin fluctuations in NFL systems.

Findings

Disorder correlates with slow spin fluctuations in NFL materials.

Local disorder theories cannot fully explain observed muon spin relaxation behaviors.

Empirical data suggest cooperative critical spin fluctuations dominate in these systems.

Abstract

Muon spin rotation and relaxation ($\mu$SR) experiments have yielded evidence that structural disorder is an important factor in many f-electron-based non-Fermi-liquid (NFL) systems. Disorder-driven mechanisms for NFL behaviour are suggested by the observed broad and strongly temperature-dependent $\mu$SR (and NMR) linewidths in several NFL compounds and alloys. Local disorder-driven theories (Kondo disorder, Griffiths-McCoy singularity) are, however, not capable of describing the time-field scaling seen in muon spin relaxation experiments, which suggest cooperative and critical spin fluctuations rather than a distribution of local fluctuation rates. A strong empirical correlation is established between electronic disorder and slow spin fluctuations in NFL materials