Interface formation in the Gd/HOPG and Dy/HOPG systems - Electron spectroscopy studies

The electronic and atomic structures of the interfaces formed upon depositi on of Gd and Dy onto HOPG(0001) at substrate temperatures of 20 and 300 K h ave been studied by AES, UPS, XPS, EELS, and LEED. At both temperatures stu died, Gd/HOPG interface reproduces atomic structure of HOPG(0001) up to 20 Angstrom thicknesses. The analysis performed by AES favors a quasi layer-by -layer growth and diffusion of Gd and Dy into interplane space of graphite even at 20 and 300 K. The structure of Dy/HOPG interface is different from that of the Gd/HOPG system: at thick coverages (45 Angstrom) when only Dy f eatures an observed by electron spectroscopy, the LEED pattern typical of c lean HOPG(0001) coexists with superstructural rings. Annealing of the inter faces at temperatures up to 1300 K induces, most probably, formation of the ordered carbide-like systems with geometrical structure analogous to that of pristine graphite for Gd-C and superstructure of root3 x root3 type for Dy-C systems. (C) 2001 Elsevier Science BN. All rights reserved.