W. Gudat

Spin‐polarized photoemission from quantum well and interface states (invited)

We examine the role of quantum well and interface states in mediating the coupling between magnetic films. We have studied with spin‐ and angle‐resolved photoemission the electronic structure of Cu on Co(100) and Ag on Fe(100). Noble metal states of sp‐derived character are found to be spin‐polarized upon contact with the magnetic materials. In Cu films up to 10 monolayer thickness polarized states have been observed. These observations are well described within the framework of one‐dimensional quantum‐well states, for film thicknesses above a few monolayers. In the low coverage regime, the hybridization with the magnetic states of the substrate strongly influences the character and the dispersion of the conduction bands.

Imaging Buried Molecules: Fullerenes Under Graphene

www.MaterialsViews.com C O M Imaging Buried Molecules: Fullerenes Under Graphene M U By Andrei Varykhalov , * Wolfgang Gudat , and Oliver Rader N IC A IO N Introducing foreign species into a semiconducting solid constitutes a very mighty means for modifying its electronic properties such as the electrical conductivity. The foreign atoms usually occupy substitutional sites of the host lattice, a fact which limits the size of the impurity atom as well as the achievable maximum concentration. This constraint is lifted for layered host materials which can accommodate also large guest atoms and even molecules, and the limit of high concentrations in these systems yields so-called intercalation compounds. [ 1 ] Graphite forms intercalation compounds with, e. g., stored hydrogen, [ 2 ]

COMPARATIVE STUDY OF THE L23-M45M45 AUGER DECAY IN CUO AND CU USING SYNCHROTRON RADIATION

Abstract We report on the evolution of L 3 – and L 2 – M 45 M 45 Auger spectral regions in Cu and CuO as a function of photon energy used to create the initial hole states. It is shown that the satellite features in Auger spectra are completely suppressed close to the threshold; intensities of these satellites increase dramatically when photon energy is swept through deeper core level thresholds. We discuss various decay channels responsible for the spectral features in the L 23 – M 45 M 45 regions of Cu and CuO and obtain quantitative estimates for their contributions to the total spectrum.

Graphene morphology on Ni single-crystal surfaces: Experimental and theoretical investigation

Experimental investigation and computer simulation of a graphite monolayer (graphene) on different Ni single-crystal surfaces have been performed. In contrast to graphene on Ni(111), which forms a solid coating with a (1 × 1) structure, graphene on Ni(110) forms a complex crystal structure which is substantially distorted by interaction with the substrate. The calculations showed that the strong chemical interaction of carbon with nickel leads to a significant bending of the graphene layer (up to few angstroms). The calculated model made it possible to predict the main result of studying graphene on faceted surfaces, which revealed the graphene ability to coat geometrically nonuniform surfaces with a curved continuous film.

Low-dimensional structures on carbon-terminated W(110): from metallic nanowires to molecular chains

In recent experiments we have discovered the unique ability of the two-dimensional tungsten surface carbideW(110)/C-R(15 × 3) to support self-organization of nanostructures with an extreme variety of physical and chemical properties. The goal of the current publication is to provide a comprehensive review of our recent achievements with this system. Using the technique of scanning tunneling microscopy we have observed one-dimensional self-assembly of noble and transition metals. Experiments with fullerene molecules have shown that C60 deposited on the surface carbide self-organizes into clusters with magic numbers and at higher coverage into chains. Angular-resolved photoelectron spectroscopy has provided comprehensive information about the electronic and chemical states in the self-assembled nanostructures.