THERMODYNAMIC AND NEAR-SURFACE CORRELATIONS IN URANIUM MONOPHOSPHIDE

Inelastic neutron-scattering measurements of the antiferromagnetic flu ctuations in uranium monophosphide above, and in the vicinity of the N eel temperature T-N are reported. At the elastic position, with suffic iently relaxed energy resolution to integrate over the low-frequency d ynamics, in the immediate neighborhood of T-N a two component wave-vec tor profile is observed. From measurements of the inelastic linewidth as a function of temperature, it is concluded that the ''broad'' compo nent in the scattered wave-vector profile represents the response of c onventional bulk thermodynamic fluctuations. These observations, taken in conjunction with an earlier magnetic x-ray-scattering study over a similar temperature interval: strongly suggest that the ''broad'' com ponent observed in the x-ray-scattering experiments has a distinct ori gin from that observed here.