Surface x-ray-diffraction measurements have been done in cobalt ultrathin films (2–12 atomic layers) grown on Pt(111). Cobalt grows, at room temperature, in an imperfect layer-by-layer mode with its own lateral lattice spacing. The packing of the atomic planes is predominantly fcc but it changes to hcp upon annealing to $\sim 450\mathrm{K}.$ Further annealing to $\sim 550\mathrm{K}$ results in alloying. Several alloys have been identified with stoichiometries close to the bulk stable phases. Resonant magnetic diffraction experiments in the $L_{\mathrm{III}}$ absorption edge of Pt allow one to determine the magnetism of the Pt atoms at the interface. By measuring magnetic crystal truncation rods, it has been found that only the Pt atoms in contact with the Co overlayer are magnetized $\left(\sim 0.2{\mu }_B\right)$ being the magnetization of the second Pt layer about ten times smaller. The induced magnetic moment of the Pt interface has been found to depend rather linearly on the thickness of the Co film, similarly to the magnetization of the overlayer. The transformation fcc to hcp of the cobalt stacking results in a ∼25% enhancement of the magnetization at the interface.

We present a multitechnique (scanning tunneling microscopy, photoelectron spectroscopy, and ion scattering spectroscopy) approach to study the formation of the Fe/Si(111) interface at room temperature. The first-deposited Fe atoms react with the surface, displacing Si atoms from their positions. The result is an amorphous layer with composition and density of states close to those of FeSi. On top of this reacted layer, crystallites of Fe with interdiffused Si grow. Upon further Fe deposition, the crystallite composition evolves to pure Fe.

Highly homogeneous, ultrathin films of copper nitride $\left({\mathrm{Cu}}_3\mathrm{N}\right)$ have been grown on Fe(001) at room temperature using a Cu evaporator and a radio-frequency plasma source to obtain atomic nitrogen in a UHV environment. ${\mathrm{Cu}}_3\mathrm{N}$ is a semiconductor with the valence band edge at $-0.65\pm 0.05\mathrm{eV}$ below the Fermi Level. The formation of copper nitride can be detected spectroscopically by the shape of the Cu LVV-Auger electron transition, which changes sensibly in shape and position compared to metallic Cu. ${\mathrm{Cu}}_3\mathrm{N}$ grows epitaxially with the substrate forming flat disklike mosaic blocks, (001) oriented. Both x-ray core level photoelectron spectroscopy and ultraviolet photoelectron spectroscopy photoemission experiments have been used to study the electronic structure. A first-principles calculation has been performed and compared with the measured spectra.

We have investigated the effect of In on the homoepitaxial growth of Cu(111) by means of surface x-ray diffraction. At the temperature range investigated (125–300 K), the growth on clean Cu occurs in a three-dimensional mode with the creation of twin crystallites over a small fraction of the total surface area. When the surface is precovered with a submonolayer amount of In, layer-by-layer growth is induced and the formation of twin crystallites is suppressed.

The structure of the low-temperature $3\times 3$ surface phase of Pb/Ge(111) has been determined by surface x-ray diffraction experiments. Analysis of the data reveals that the Pb layer exhibits a vertical corrugation of $\sim 0.4Å$, affecting also the two top Ge layers. Significant distortions are found down to the third Ge layer. This structural model supports that the $3\times 3$ ground state can be best described as a cooperative distortion stabilized by a gain in electronic energy.

Surface magnetic x-ray diffraction experiments have been done on the (111) surface of the ferromagnetic alloy C${\mathrm{o}}_3$Pt. This has been achieved by tuning the photon energy to the $L_{\mathrm{III}}$ absorption edge of Pt in order to benefit from the increased magnetic cross section at resonance. Analysis of the data reveals that the magnetism of the Pt atoms on the first atomic layer is smaller by about a factor of 2 than that of the Pt atoms in the bulk, the reason probably being the reduced Co concentration at the surface.