Low-energy electron diffraction structure studies of thin films of Fe on W(001) and of oxygen-exposed thin films of Fe on Ag(001)
Low Energy Electron Diffraction (LEED) has been used to determine the structure of ultrathin films (1 and 2 monolayers) of Fe on W(001), by conducting LEED Intensity versus Voltage (LEED IV) analysis and comparison with experimental data. Spot Profile LEED (SPA-LEED) has been used to determine the changes in the long-range order induced by oxygen chemisorption on ultrathin films of Fe on Ag(001). Disagreement concerning the magnetic and structural properties of ultrathin films of Fe on Ag(001) led to the study of the structural properties of these films after they were exposed to oxygen. Spot Profile LEED was used to determine the change in the epitaxial growth mode of the films, which showed that oxygen was bonding strongly to the overlayer Fe atoms in such a way as to increase the average terrace width of the three dimensional islands that existed prior to oxygen adsorption and to flatten the surface. LEED IV analysis of 1 ML and 2 ML Fe films on W(001) showed that the structure of the films was body centered tetragonal with lattice parameters a = 3.16 [angstrom] and c = 2.75 [angstrom]. The 1 ML films was determined to lie 1.06 [angstrom] above the top W layer, which corresponds to a contraction of 32.9% with respect to the bulk W interlayer spacing, explaining the observed disappearance of ferromagnetism for the 1 ML film since strong hybridization of the bands takes place. The second interlayer spacing (d[sub 23]) was expanding by 1.26%. In the 2 ML film the top interlayer spacing (d[sub 12]) was contracted by 22.78%, the second interlayer spacing (d[sub 23]) was contracted by 3.16% and the third interlayer spacing (d[sub 34]) was contracted by 14.5% with respect to the bulk.
- Research Organization:
- Texas Univ., Austin, TX (United States)
- OSTI ID:
- 7104949
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON DIFFRACTION
ELEMENTS
FILMS
GOLD
IRON
LATTICE PARAMETERS
LAYERS
MAGNETIC PROPERTIES
METALS
PHYSICAL PROPERTIES
SCATTERING
SEPARATION PROCESSES
SORPTION
STRUCTURAL CHEMICAL ANALYSIS
THIN FILMS
TRANSITION ELEMENTS
TUNGSTEN