The epitaxial growth of Fe monolayers on the unreconstructed Ir͑001͒ surface was investigated experimentally by determining film structure, morphology, stress, and magnetism. Our combined quantitative low energy electron diffraction ͑LEED͒ and cantilever stress results indicate pseudomorphic Fe growth with a constant in-plane film strain in an almost perfect layer-by-layer growth mode from 0-10 layers. The combination of the structural analysis by LEED with stress measurements suggests that the first two layers of Fe grow as a face-centered tetragonally ͑fct͒ distorted precursor. Further deposition of Fe leads to the growth of a bodycentered tetragonally distorted phase on top of the fct precursor, which retains its structure. The magnetooptical Kerr effect reveals that the Fe film is ferromagnetic with an in-plane easy magnetization direction along Fe͗100͘.

Geometric parameters of NiO films epitaxially grown on Ag(001) were determined using two independent experimental techniques and ab initio simulations. Primary beam diffraction modulated electron emission experiments determined that the NiO films grow with O on top of Ag and that the oxide/metal interface distance is d=2.3+/-0.1 A. Polarization-dependent x-ray absorption, at the Ni-K edge, determined the tetragonal strain (r( parallel )=2.046+/-0.009 A, r( perpendicular )=2.12+/-0.02 A) and d=2.37+/-0.05 A. Periodic slab model results agree with the experiments (d=2.40, r( parallel )=2.07, r( perpendicular )=2.10 A; the O-on-top configuration is the most stable).

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We report on the formation of ultrathin Co oxide films by oxidation of correspondingly thin Co films epitaxially grown on the unreconstructed-i.e., metastable-͑1 ϫ 1͒ phase of Ir͑100͒, on both the clean surface and the surface precovered with half a monolayer of oxygen. As investigated by low-energy electron diffraction patterns and intensities and by atomically resolved images from scanning tunneling microscopy ͑STM͒ the oxide forms mainly in its fcc-type rocksalt structure CoO. This is with exception of the submonolayer range and the surface precovered with oxygen for which the Co 3 O 4 spinel-structured phase develops. Rather unusual, the CoO films appear in the polar ͑111͒ orientation and so, though the hexagons are slightly distorted, should become increasingly instable with growing thickness. However, STM images recorded under special conditions indicate that there are oxygen vacancies which lead to charge compensation and so may contribute to stabilize the ͑111͒ orientation. Also, STM retrieves a considerable buckling of cobalt layers which is inevitable when fcc͑111͒ layers are accommodated on an fcc͑100͒ substrate.