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Abstract: Barium ferrite thin films were spin-coated on sapphire (00l) faces. Ethylene-diamine-tetra-acetic acid (EDTA) was used to chelate metal ions. The conditions to obtain highly textured films were expanded by using EDTA, where the pH values of the solutions varied from 3 up to 9 and the molar ratio of EDTA to metal ions changed from 1.0 up to 1.5. The grains showed that the c-axis aligned normal to the film plane and the [110] direction of sapphire was parallel to the [100] direction of the film. The film showed uniaxial magnetic anisotropy with the coercivity field of 21.5kA/m along the out-of-plane direction and very small hysteresis in the in-plane direction. The coercivity was likely to be controlled by wall nucleation according to the shape of the curves of the coercivity forces versus the maximum applied field. [Copyright &y& Elsevier]

Abstract: M-type barium ferrite thin films were deposited onto sapphire (00l) substrates by radio frequency magnetron sputtering. Columnar grains were formed on the surface of the films under lower sputter pressure with bubble magnetic domains, which is originated from high magnetocrystalline anisotropy of the film. Magnetic hysteresis loops agree with the change of the morphology, where in-plane and out-of-plane loops are quite different of the samples prepared under high sputtering pressures, while they are almost identical under low pressures. The influence of the sputtering pressure was understood by that with the increase of the pressure, resputtering of the film is hindered. Nucleation with c-axis normal to the film plane was enhanced. Thus samples prepared under low pressure have more acicular crystallites which have c-axis parallel to the film plane. [Copyright &y& Elsevier]

Abstract: Hexagonal barium ferrites were deposited onto sapphire substrates by radio frequency magnetron sputtering. The composition, microstructure, and magnetic properties of these isotropic thin films were investigated with Rutherford backscattering spectroscopy, X-ray diffraction, atomic force microscopy, magnetic force microscopy and SQUID magnetometry. The intrinsic coercivity of the films reaches about 11.5kOe at room temperature. The mechanism of the coercivity is proposed to be nucleation in the decoupled single domain nanometer particles as shown by the characteristics of the magnetic domains and the virgin magnetization curves. [Copyright &y& Elsevier]

Abstract: Hexagonal barium ferrite thin films were fabricated by spin coating of precursors obtained by sol-gel methods onto sapphire (00l) faces. Citric acid and ethylenediaminetetraacetic acid (EDTA) were used to tune the morphology of the films. The films show texture with c-axis normal to the film plane as shown by the strong x-ray diffractions from the (001) plane with full width at half maximum of the rocking curves about 0.4°. The [100] direction of the film is parallel to the [110] direction of the sapphire. With the increase of the citric acid, the percentage of the acicular crystallites increased. EDTA can be used to produce films with the best texture where faceted grains were obtained. The maximum coercive force obtained was about 302 kA/m. [Copyright &y& Elsevier]

Abstract: Hexagonal barium ferrite (BaM) thin films have been prepared by sol–gel technique involving spin coating and annealing in air. Different ratios of Ba to Fe, different annealing temperatures and different annealing time are explored. X-ray diffraction shows that the films have been epitaxially grown on the sapphire (001) plane with [100] direction of BaM parallel to [110] of Al2O3, and the c-axes of them being parallel, while magnetic measurements show magnetically anisotropic loops with in-plane and out-of-plane intrinsic coercivity of 87.5kA/m and 230.8kA/m, respectively. [Copyright &y& Elsevier]

Abstract: Hexagonal barium ferrite (BaFe12O19) thin films were fabricated by spin coating of precursors from sol–gel methods. Different amount of citric acid was added. Weight loss and changes of chemical bonds during the heat treatment below 500°C were recorded by thermogravity analyzer and Fourier transform infrared spectroscopy, respectively. The morphology of the films, i.e. the amount of acicular crystallites in the film, was controlled by adjusting the quantity of citric acid. The X-ray diffraction shows that the films are c-axis oriented, but the crystallization is less perfect with the increase of the citric acid. With the increase of the citric acid, the percentage of the acicular crystallites increased. At the same time, the coercivity force increased. The acicular crystallites were not exchange-coupled to the platelet crystallites. The citric acid was understood to form complex with iron ions and accelerate the exothermal auto-combustion. The c-axis oriented growth of the film was thus deteriorated. [ABSTRACT FROM AUTHOR]

Abstract: Barium ferrite thin films have been prepared by radio frequency magnetron sputtering on a sapphire (001) substrate at substrate temperature of 500°C and 650°C, respectively. The films were further annealed in air at 1000°C for 5h. X-ray diffraction shows that the films at the lower substrate temperatures have a good epitaxial relation with respect to the substrate, while the samples under the higher substrate temperatures have (109) planes parallel to the substrate. The remanence ratio decreases from 0.82 to 0.47 when the substrate temperature is increased. We attribute the variation of the growth direction to the enhanced vertical mobility of the deposited atoms when the substrate temperature is increased. [Copyright &y& Elsevier]