Growth and electronic and magnetic structure of iron oxide films on Pt(111)

Abstract

Ultrathin (111)-oriented polar iron oxide films were grown on a Pt(111) single crystal either by the reactive deposition of iron or oxidation of metallic iron monolayers. These films were characterized using low-energy electron diffraction, scanning tunneling microscopy, and conversion electron M\"ossbauer spectroscopy. The reactive deposition of Fe led to the island growth of Fe${}_{3}$O${}_{4}$, in which the electronic and magnetic properties of the bulk material were modulated by superparamagnetic size effects for thicknesses below 2 nm, revealing specific surface and interface features. In contrast, the oxide films with FeO stoichiometry, which could be stabilized as thick as 4 nm under special preparation conditions, had electronic and magnetic properties that were very different from their bulk counterpart w\"ustite. Unusual long-range magnetic order appeared at room temperature for thicknesses between 3 and 10 monolayers, the appearance of which requires severe structural modification from the rock-salt structure.