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The spin polarising properties of the iron oxide magnetite ( Fe 3 O 4 ) make it attractive for use in spintronic devices, but its sensitivity to compositional and structural variations make it challenging to prepare reliably. Infrared microspectroscopy and modelling are used to determine the spatial variation in the chemical composition of three thin films of iron oxide; one prepared by pulsed laser deposition (PLD), one by molecular beam epitaxy (MBE) deposition of iron whilst simultaneously flowing oxygen into the chamber and one by flowing oxygen only once deposition is complete. The technique is easily able to distinguish between films which contain metallic iron and different iron oxide phases as well as spatial variations in composition across the films. The film grown by post-oxidising iron is spatially uniform but not fully oxidised, the film grown by simultaneously oxidising iron showed spatial variation in oxide composition while the film grown by PLD was spatially uniform magnetite. [ABSTRACT FROM AUTHOR]

The growth and magnetic properties of epitaxial magnetite Fe3O4 on Si(100) using MgO buffer layer have been studied by reflection high-energy electron diffraction, X-ray photoelectron spectroscopy, and magneto-optical Kerr effect. The epitaxial Fe3O4 films were prepared by in situ post growth annealing of ultrathin epitaxial Fe films at 220 °C in an oxygen partial pressure of 8 × 10-4 mbar. The epitaxial relationship was found to be Fe3O4(100)(001)//MgO(100)(001)//Si(100)(001) with the MgO film grown cube-on-cube orientation with the Si substrate. While the Fe unit cell rotates 450 to match that of the MgO buffer layer, it rotates 45° back upon oxidation. A low saturation field has been observed indicating low density of antiphase boundaries. [ABSTRACT FROM AUTHOR]

In this paper, the authors report on the investigation on the effect of inserting an epitaxial MgO layer on the structural and magnetic properties of Fe[sub3]O[sub4] ultrathin films grown on GaAs(100) by combined techniques of molecular beam epitaxy and postgrowth annealing in an oxygen atmosphere. The MgO films were grown with a cube-on-cube orientation to GaAs. The epitaxial Fe[sub3]O[sub4] lattice cell was rotated by 45° in respect to that of MgO and GaAs due to the lattice relaxation of the magnetic layer. All samples studied exhibited strong fourfold cubic magnetic anisotropy with easy axes along the (001) directions of GaAs. A dramatic decrease in the uniaxial anisotropy constant in the presence of the MgO barrier was observed. The existence of the uniaxial magnetic anisotropy in the Fe[sub3]O[sub4]/GaAs hybrid structure has been attributed to the interfacial contact between the magnetite film and the GaAs. [ABSTRACT FROM AUTHOR]

Ultrathin Fe oxide films of various thicknesses prepared by post-growth oxidation on GaAs(100) surface have been investigated with X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD). The XPS confirms that the surfaces of the oxide are Fe3 O4 rather than Fe2O3. XAS and XMCD measurements indicate the presence of insulating Fe divalent oxide phases (FeO) beneath the surface Fe3 O4 layer with the sample thickness above 4 nm. This FeO might act as a barrier for the spin injection into the GaAs. [ABSTRACT FROM AUTHOR]