Spin dynamics at the magnetic instability in CeCu6-xAux

Extensive neutron scattering is used to obtain S(q,omega) of the heavy-ferm ion alloy CeCu6 - xAux at the magnetic instability, i.e. x = 0.1. The measu red dynamic correlations reveal rod-like structures in the reciprocal ac pl ane corresponding to two-dimensional fluctuations in real space. These fluc tuations together with the observed three-dimensional magnetic ordering in alloys with higher Au content provide an explanation for the unusual non-Fe rmi-liquid behaviour in CeCu5.9Au0.1. (C) 1999 Elsevier Science B.V. All ri ghts reserved.