Magnetic field effect at the quantum critical point in CeCu6−xAux from Cu NQR–NMR relaxation

Abstract 63 Cu NQR–NMR relaxation measurements in CeCu 5.9 Au 0.1 are used to achieve insights on the k -integrated, low-energy, generalized susceptibility χ( k ,ω,H,T→0) around the quantum critical point. The response function indicated by neutron scattering, namely of 2D character with anomalous exponent and with ( ω / T ) scaling, appears to justify the main experimental findings. A breakdown of that form of χ is found to occur below a field-dependent temperature T ∗ (H) , where a behavior characteristic of a gapped system sets in.