A novel nonpolar structure of 2 monolayer (ML) thick ZnO(0001) films grown on Ag(111) has been revealed, using surface x-ray diffraction and scanning tunneling microscopy. Zn and O atoms are arranged in planar sheets like in the hexagonal boron-nitride prototype structure. The observed depolarization is accompanied by a significant lateral 1.6% expansion of the lattice parameter and a 3% reduced Zn-O bond length within the sheets. The nonpolar structure stabilizes an atomically flat surface morphology unseen for ZnO surfaces thus far. The transition to the bulk wurtzite structure occurs in the 3-4 ML coverage range, connected to considerable roughening.

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Using spin-polarized scanning tunneling microscopy, the local excitation of magnons in Fe and Co has been studied. A large cross section for magnon excitation was found for bulk Fe samples while for thin Co films on Cu(111) the cross section linearly scales with film thickness. Recording inelastic tunneling spectra with Fe coated W tips in a magnetic field, the magnonic nature of the excitation was proven. Magnon excitation could be detected without the use of a separating insulating layer opening up the possibility to directly study magnons in magnetic nanostructures via spin-polarized currents.

Combined experimental and ab initio studies show that the surface-state-mediated adatom-step and adatomadatom interactions are the driving forces for the self-organization of Fe adatoms on vicinal Cu͑111͒ surfaces at low temperatures. Our scanning tunneling microscope observations and the kinetic Monte Carlo simulations reveal the self-organization of Fe adatoms into atomic strings. The interatomic separation ͑1.2 nm͒ in the strings is not determined by the nearest-neighbor distance ͑0.26 nm͒ of the Cu atoms along the step edge but by the wavelength of the surface-state charge density oscillations.

We demonstrate that a size-dependent mesoscopic mismatch exists in homoepitaxy, which has a strong impact on the morphology of the islands and the substrate. Atomic scale calculations for double layer Cu islands on Cu(111) reveal that mesoscopic strain relaxations in both islands and the substrate strongly influence the shape of islands and can effect the details of atomic motion near the island.