Interplay between structural, magnetic, and electronic properties in a FeO/Pt(111) ultrathin film

We have investigated the magnetic and electronic properties of a FeO film grown on Pt(111). Coupling first-principles density-functional theory calculations with scanning tunneling microscopy (STM) measurements we have identified the principal mechanisms for the structural and electronic characteristics observed in the Moire unit cell formed between oxide film and metal support. We show that both free and supported FeO(111) monolayers present an antiparallel alignment of the magnetic moments. Due to the lattice mismatch between Pt(111) and the FeO film, the interface properties are different in different regions of the supercell. The resulting modulation of the structural and electronic properties of the film is determined by the strength of the film-substrate interaction in various regions of the supercell. In particular, for the Fe-top site, where this interaction is weak, there is a small rumpling of the FeO layer which increases the interface separation. In correspondence of this structural modification, we observe a change in the work function, coherent with the most recent experimental findings. Our results show that a good agreement with the experimental interpretation of the work function modulation and of the STM images can be obtained only within the more robust, nonpseudomorphic computational models.