non-Local Quantum Criticality in Ce(Ru_{1-x} Fe_x)_2 Ge_2 (x = x_c = 0.76)

TL;DR

This study investigates quantum critical behavior in Ce(Ru_{0.24}Fe_{0.76})_2Ge_2 using neutron scattering, revealing critical long-range fluctuations influenced by the Kondo effect and proposing a model for non-Fermi liquid scaling.

Contribution

It provides experimental evidence of non-local quantum criticality and introduces a phenomenological model for susceptibility in this compound.

Findings

Observation of critical long-range fluctuations near the quantum critical point

Identification of non-Fermi liquid E/T scaling at all wave vectors

Proposal of a phenomenological susceptibility expression

Abstract

We present the results of inelastic neutron scattering measurements, performed near the antiferromagnetic quantum critical point in Ce(Ru_{0.24} Fe_{0.76})_2 Ge_2. Both local and long range fluctuations of the local moments are observed, but due to the Kondo effect only the latter are critical. We propose a phenomenological expression which fits the energy $E$, temperature T and wave vector q dependences of the generalized susceptibility chi(q,E,T), describing the non-Fermi liquid E/T scaling found at every wave vector.