In this work, recent studies of surface magnetism, as observed by x-ray scattering techniques, are described. The experiments were concerned with uranium dioxide crystals for which x-ray resonance effects enhance the small magnetic signal from the surface. The main result is that, in contrast to the bulk which exhibits a discontinuous magnetic ordering transition, both the (001) and (111) surface layers order continuously. This is reminiscent of the general phenomenon of surface wetting, but had not been previously observed for magnetic materials. Magnetic reflectivity studies show further that the near-surface magnetic layers are more disordered than layers deep in the bulk, even at low temperatures.
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