Hall Effect anomalies near Quantum Critical Point in CeCu6-xAux

TL;DR

This study investigates the Hall effect anomalies near the quantum critical point in CeCu6-xAux compounds, revealing complex temperature-dependent behaviors and divergence of harmonic contributions associated with quantum criticality.

Contribution

The paper provides detailed experimental analysis of Hall effect anomalies in CeCu6-xAux near quantum criticality, including activation energies, microscopic parameters, and harmonic contributions, which are novel insights into heavy fermion behavior.

Findings

Activation energies identified in Hall coefficient.

Divergence of second harmonic term near T*.

Power-law behavior of Hall coefficient at quantum criticality.

Abstract

Precision measurements of the Hall effect have been carried out for both archetypal heavy fermion compound - CeCu6 and exemplary solid solutions CeCu6-xAux (x= 0.1 and 0.2) with quantum critical behavior. The experimental results have been obtained by technique with a sample rotation in magnetic field in the temperature range 1.8-300K. The experiment revealed a complex activation type dependence of the Hall coefficient RH(T) in CeCu6 with activation energies Ea1/kB = 110K and Ea2/kB = 1.5K in temperature ranges 50-300K and 3-10K, respectively. Microscopic parameters of charge carriers transport (effective masses, relaxation time) and localization radii ap1,2* of heavy fermions (ap1*(T>50K)= 1.7 A and ap2*(T<20K)= 14 A) were estimated for CeCu6. The second angular harmonic contribution has been established in the Hall voltage of CeCu5.9Au0.1 and CeCu6 at temperatures below T*=24K. A hyperbolic type divergence of the second harmonic term in Hall effect RH2(T)= C(1/T-1/T*) at low temperatures is found to be accompanied with a power-law behavior RH(T)= T -0.4 of the main contribution in the Hall coefficient for CeCu5.9Au0.1 compound with quantum critical behavior.