1 MeV Ar+ and Kr+ ion irradiation induced intermixing in single- and bi-layer Fe3O4 films grown on MgO(001) single crystals

Abstract

The layer composition and crystallinity of single-layer Fe3O4(001) and bi-layer Fe3O4/Fe(001) thin films grown epitaxially on MgO(001) substrates have been investigated by Rutherford backscattering spectrometry (RBS), channeling experiments (RBS-C) and X-ray reflectometry (XRR). Four thin films with similar film layer structure but different layer thickness have been irradiated by 1 MeV Ar+ or 1 MeV Kr+ ion beam with ion fluences in the range of ~0.8–20.7 × 1016 ions/cm2 for a detail underlining the ion mixing effect and its influence on the layer stability. The ion fluence of 4.4 × 1016 Ar+/cm2 and 0.8 × 1016 Kr+/cm2 was enough to change the stoichiometry of the Fe3O4 layer in the single-layer Fe3O4 films, while the stoichiometric Fe3O4 layer on the surface of bi-layer films were well preserved at a much higher Ar+ and Kr+ ion fluence (20.7 × 1016 Ar+/cm2 and 2.5 × 1016 Kr+/cm2), despite that such ion fluencies could induce a complete oxidization of the buffer Fe layer. The stability of the Fe3O4 layer and the bilayer structure of the film after Ar+ ion irradiations at an ion fluence about 10 times larger than that of Kr+ ion indicate a high potential for practical applications of the bilayer magnetite films in an argon atmosphere.