AN X-RAY REFLECTIVITY STUDY OF SURFACE LAYERING IN A MAGNETIC FLUID

By utilizing an x-ray diffractometer for the observation of liquid sur faces, the depth profile of the electron density of a magnetic fluid a cross the surface was studied. The observed x-ray reflectivity indicat ed oscillatory behaviour in the electron density along the surface-nor mal direction. The layer spacing is comparable to the dimensions of th e magnetic fine particles. The temperature dependence of this long-ran ge-ordered surface structure exhibited a distinctive feature: not only the period but also the amplitude and the decay length of the electro n density oscillations increase with increasing temperature. The resul ts are compared with features of the surface layering observed for met allic liquids.