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Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films
Published on: December 4, 2014
Structural analysis of FeO(1 1 1)/Ag(0 0 1): undulation of hexagonal oxide monolayers due to square lattice metal
1Department of Physics, University of Osnabrück, Barbarastr. 7, D-49069, Germany.
Abstract:
Iron oxide monolayers are grown on Ag(0 0 1) via reactive molecular beam epitaxy (metal deposition in oxygen atmosphere). The monolayer shows FeO stoichiometry as concluded from x-ray photoemission spectra. Both low energy electron diffraction as well as scanning tunneling microscopy demonstrate that the FeO layer has a quasi-hexagonal (1 1 1) structure although deposited on a surface with square symmetry. Compared to bulk values, the FeO(1 1 1) monolayer is unidirectionally expanded by 3.4% in [Formula: see text] directions while bulk values are maintained in [Formula: see text] directions. In [Formula: see text] directions, this lattice mismatch between FeO(1 1 1) monolayer and Ag(0 0 1) causes a commensurate undulation of the FeO monolayer where 18 atomic rows of the FeO(1 1 1) monolayer match 17 atomic rows of the Ag(0 0 1) substrate. In [Formula: see text] directions, however, the FeO(1 1 1) monolayer has an incommensurate structure.
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