INTERFACE FORMATION IN RARE-EARTH OVERLAYER SYSTEMS

Photoemission studies reveal that intermixed interface layers form when rare earths are deposited onto various metallic substrates at room temperature. The following systems have been investigated: Ce on Au, Ce on Cu, Ce on Al, and La on Mg. Such intermixed regions are argued to be amorphous in nature, since they are being formed at temperatures that are well below those where nucleation and crystalline growth are expected to occur. Interactions between deposited and substrate material are witnessed by core level shifts in substrate photoemission peaks. Deviations from exponential attenuation of substrate emission indicate that even overlayers are not formed. Simplistic models for the mixed interface are used to estimate the extent of the interface and the average volume fraction of deposited and substrate material in the interface.