Scaling of magnetic fluctuations near a quantum phase transition

TL;DR

This study investigates magnetic fluctuations near a quantum phase transition in a heavy fermion alloy using neutron scattering, revealing (E/T) scaling and a quantum Lifshitz point, advancing understanding of quantum criticality.

Contribution

It provides experimental evidence of (E/T) scaling and quasi-low dimensionality in magnetic fluctuations near a quantum critical point in a heavy fermion system.

Findings

Magnetic fluctuations obey (E/T) scaling near the critical point.

Data consistent with a quantum Lifshitz point.

Anomalous exponent a=0.8 observed in susceptibility.

Abstract

We use inelastic neutron scattering to measure the magnetic fluctuations in a single crystal of the heavy fermion alloy CeCu_5.9Au_0.1 close to the antiferromagnetic quantum critical point. The energy and temperature-dependent spectra obey (E/T) scaling at Q near (1,0,0). The neutron data and earlier bulk susceptibility are consistent with the form 1/X ~ f(Q)+(-iE+bT)^a, with an anomalous exponent a=0.8. We confirm the earlier observation of quasi-low dimensionality and show how both the magnetic fluctuations and the thermodynamics can be understood in terms of a quantum Lifshitz point.