Magnetic field effect at the quantum critical point from NQR-NMR relaxation

63Cu NQR–NMR relaxation measurements in CeCu5.9Au0.1 are used to achieve insights on the k-integrated, lowenergy,
generalized susceptibility chi(k,w,H,T->0) around the quantum critical point. The response function indicated by neutron scattering, namely of 2D character with anomalous exponent and with (w/T) scaling, appears to justify the main experimental findings. A breakdown of that form of w is found to occur below a field-dependent temperature T*(H); where a behavior characteristic of a gapped system sets in.