EPITAXY OF THIN CR LAYERS ON CU(001)

Thin Cr films (6-30 monolayers) have been evaporated in ultra-high vacuum onto a Cu(001) single crystal kept at room temperature and have been studied by low energy electron diffraction (LEED), X-ray photoelectron diffraction (XPD), and angle resolved ultra-violet photoemission (ARUPS). The LEED diagrams obtained for these layers reveal the formation of epitaxial body-centered cubic (bcc) Cr domains with Cr(110) parallel-to Cu(001) and Cr[111BAR] parallel-to Cu[110]. The Cu(001) substrate symmetry results in four different orientations of these domains. This conclusion is confirmed by the XPD data. Indeed the modulations of the Cr2P3/2 core level intensity as a function of emission angle are in agreement with single scattering simulations performed for a superposition of equivalent bcc Cr(110) domains on a Cu(001) substrate. Moreover, ARUPS results at normal emission also indicate that the Cr film exposes a (110) surface.