CRYSTALLOGRAPHIC AND ELECTRONIC-STRUCTURE OF CU CR/CU(001) SANDWICHES/

Thin Cu layers have been evaporated at room temperature on Cr films (s imilar to 10 monolayers) deposited on a Cu(001) single crystal. The cr ystallographic structure of these sandwiches is analysed by means of l ow-energy electron diffraction (LEED), angle-resolved ultra-violet pho toemission spectroscopy (ARUPS) and X-ray photoemission spectroscopy. The data show that the attenuation of the Cr signal versus Cu depositi on is much lower than expected for a uniform film growth. Moreover, th e LEED pattern characteristic of the Cr film (made of Cr(110) domains with four different orientations) is visible for Cu coverages as high as 23 ML. This indicates a strong diffusion of the Cu atoms on the Cr film surface and the formation of Cu three-dimensional islands which p resent, according to ARUPS and X-ray photoelectron diffraction measure ments, a highly disordered fee crystallographic structure. However the low reactivity of the sandwiches towards oxygen suggests that the who le Cr surface is wetted by at least 1 ML of Cu.