Disorder-Driven Non-Fermi-Liquid Behavior in CeRhRuSi_2

TL;DR

This study investigates how disorder influences non-Fermi-liquid behavior in CeRhRuSi_2, revealing a disorder-driven mechanism with a low-temperature crossover to Fermi-liquid behavior, supported by magnetic susceptibility and NMR measurements.

Contribution

It provides experimental evidence linking disorder to NFL behavior in CeRhRuSi_2 and highlights the necessity to extend existing theories to include low-temperature crossover effects.

Findings

Linewidth increases with decreasing temperature, indicating local susceptibility distributions.

NMR linewidths match distribution functions fitting bulk susceptibility and heat capacity.

Below 1 K, behavior suggests a crossover to Fermi-liquid state with vanishing susceptibility distributions.

Abstract

We report measurements of the bulk magnetic susceptibility and ^{29}Si nuclear magnetic resonance (NMR) linewidth in the heavy-fermion alloy CeRhRuSi_2. The linewidth increases rapidly with decreasing temperature and reaches large values at low temperatures, which strongly suggests the wide distributions of local susceptibilities \chi_j obtained in disorder-driven theories of non-Fermi-liquid (NFL) behavior. The NMR linewidths agree well with distribution functions P(\chi) which fit bulk susceptibility and specific heat data. The apparent return to Fermi-liquid behavior observed below 1 K is manifested in the vanishing of P(\chi) as \chi \to \infty, suggesting the absence of strong magnetic response at low energies. Our results indicate the need for an extension of some current theories of disorder-driven NFL behavior in order to incorporate this low-temperature crossover.