Rotated incommensurate domains of Co ultrathin films on Pt(111)

Low energy electron diffraction (LEED) and Auger electron spectroscopy were used to study the initial growth of cobalt ultrathin films on a Pt(111) surface at room and low temperatures. The films show incoherent epitaxy at room temperature. Unrotated and rotated incommensurate Co domains with two equivalent angles of rotation, +4.9° and -4.9°, with respect to the aligned substrate, are observed by LEED for 2 monolayers of Co/Pt(111) after applying an annealing treatment. From a calculation of the mismatch for the corrugated surface, we confirm this reorientation angle. The evolution of the LEED satellite pattern for the deposition at 140 K is the same as for the deposition at room temperature, but a faint (2 × 2) LEED pattern was observed for higher coverages. UV photoelectron spectroscopy was used to monitor the evolution of the density of electronic states during deposition.