Epitaxial growth of Fe islands on LaAlO3 (001) substrates

Fe deposits were performed on LaAlO3 (001) by molecular beam epitaxy at different substrate temperatures. Chemical and structural characterizations were carried out in-situ, by X-ray photoelectron spectroscopy (XPS), reflection high-energy electron diffraction (RHEED), X-ray photoelectron diffraction (XPD), and ex-situ by high-resolution transmission electron microscopy (HRTEM). This temperature dependence study indicates that the growth of Fe is epitaxial in a tight temperature window around 500°C with a single epitaxial relationship, where the Fe and LaAlO3(001) lattices are brought into coincidence by a 45° rotation around the common [001] axis. This typical configuration via Fe–O bonds formation at the interface allows a minimization of the elastic strain inside Fe islands which follow a Volmer–Weber growth mode. Beyond a given thickness, and in agreement with the strain relaxation, Fe islands exhibit (001) facets, leading to islands coalescence and a possible iron 2D layer formation.