The growth of Fe overlayers on Ag(100)

Using LEED and Auger spectroscopy the growth of Fe overlayers on Ag(100) was observed to follow an epitaxial layer-by-layer mode for three monolayers, after which islanding occurred. The large (0.9 eV) work function change seen on deposition is not consistent with the prediction of either the uniform positive background model or the virtual level model of adsorbate-induced work function change.     

Analysis of the electronic structure of ultrathin NiO/Ag(100) films

Thin films of nickel oxide on a silver substrate have been extensively studied both experimentally and theoretically. In this paper we present band structure calculations of one, two, three and five layer NiO/Ag(100) systems using a GGA+U density functional method and study the approach of the system towards the bulk situation. We find that the interfacial layer is metallised and that even for a five-layer system, the substrate still affects the properties of the outermost and central layers, suggesting that these layers have not yet reached convergence towards bulk properties. This may affect some of the more sensitive properties of the system.     

Magnetic and structural properties of Fe(110)/Ag(111) and Fe(100)/Ag(100) multilayers

A comparison of the magnetic and structural properties and growth characteristics between Fe(110)/Ag(111) and Fe(100)/Ag(100) multilayers is presented. The two types of multilayers were made of the same constituent materials but with different oricutations, allowing us to examine the interesting interplay between structure and magnetism. We found fundamentally different magnetic properties including magnetocrystalline anisotropy and surface/interface and thin film magnetism for the two types of multilayers, and their origins were discussed. Presently at the Naval Research Laboratory. Presently at Argonne National Laboratory.     

Umklapp-mediated quantization of electronic states in Ag films on Ge(111)

We employ angle-resolved photoemission to study the electronic structure of atomically uniform films of Ag grown on Ge(111). A new kind of quantum well state is observed near a specific emission direction away from the surface normal. In contrast with the usual quantum well state arising from electron confinement by specular reflections at the surface and interface of the film, the new kind involves retroreflections, or umklapp reflections, at the interface. It requires four reflections, instead of the usual two reflections, to complete a coherent interference path.     

Crystallographic structure of ultrathin Fe films on Cu(100)

We report the observation of bcc-like crystal structures in 2-4 monolayer (ML) Fe films grown on fcc Cu(100) using scanning tunneling microscopy. The local bcc structure provides a straightforward explanation for their frequently reported outstanding magnetic properties, i.e., ferromagnetic ordering in all layers with a Curie temperature above 300 K. The nonpseudomorphic structure, which becomes pseudomorphic above 4 ML film thickness, is unexpected in terms of conventional rules of thin film growth and stresses the importance of finite thickness effects in ferromagnetic ultrathin films.     

Epitaxial growth of fcc Fe on Cu(100)

Layer-by-layer epitaxial growth of Fe on Cu(100) is reported. The epitaxy is characterized using Auger electron spectroscopy and low energy electron diffraction intensity analysis. Good quality epitaxial Fe films having thicknesses ranging from one to four monolayers are stabilized by the Cu(100) substrate. The overlayer structure is shown to be nearly identical to a continuation of the fcc lattice of the substrate.