The nanocrystalline MnxFe3−xO4 (x=0, 1.18, 1.56, and 1.9) spinel ferrite thin films were investigated by means of the x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Mn and Fe L2,3 edges. The cationic distributions of thin spinel ferrite films for x=1.18 and 1.56 were determined using a crystal field atomic multiplets scheme for arbitrary symmetry. The results are compared with the distribution of cations obtained from the differential thermogravimetry analysis of fine powders of corresponding compositions.

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Cubic spinel ferrite films containing cobalt, copper and manganese were prepared by the rf sputtering from targets formed by intimate mixtures of ferrite powders. Additional heat-treatments at temperatures of about 450°C introduce cation vacancies which have positive influence on the magneto-optical properties of films. Figure of merit shows maxima at 600, 850 and 1500 nm which classifies these films to promissing materials for magneto-optical recording.

X-ray magnetic circular dichroism at the Fe L2,3, Ce M4,5 and Ce L2,3 absorption edges of CeFe2 are reported. Application of the sum rules yields both the magnitude and the direction of the magnetic contributions (Fe 3d, Ce 5d and Ce 4f) to the total moment in CeFe2. A total Ce magnetic contribution of − 0.29μB (M5d = − 0.13μB, M4f = − 0.16μB) and a ratio for the 4f contribution ⟨Lz⟩/⟨Sz⟩ ≈ − 1 are found, which confirms that the 4f states are highly hybridised in CeFe2. These results are in good agreement with previously published LSDA calculations.

Optical absorption and Faraday rotation of copper and cobalt-manganese ferrite thin films, prepared by sputtering, were measured in the visible and near infrared spectral regions. Main magneto-optical features can be explained by the respective transitions of Cu 2+ and Co 2+ ions tetrahedrally and octahedrally coordinated. Annealings at 450 and 665°C cause migration of these ions into tetrahedral positions and, consequently, increase corresponding peaks in the figure of merit Therefore, these films range among the promissing materials for the magnetooptical recording.

Optical reflection and the polar Kerr rotation of four single crystals of barium hexagonal ferrites were measured in the visible and near infrared region at room temperature. Local extrema of the polar Kerr rotation at wavelengths of 1650, 1350 and 760 nm could be assigned to the presence of Co2+ in tetrahedral positions. The figure of merit attains the maximum values at these wavelengths suggesting material to be suitable for the magneto-optical storage applications.

The absorption coefficients and the Faraday rotation spectra of nanocrystalline cobalt ferrite thin films were determined in the visible–near infrared range. The films prepared by rf sputtering in an Ar–O2 atmosphere display magnetic and structural properties which differ from those of the bulk material. Optical and magneto-optical transitions observed in the films are identified by comparing our spectra with those obtained with well characterized bulk materials. In the bulk, cations with an octahedral environment (point group 3̄m) locate on a center of symmetry and the corresponding optical transitions have a very small oscillator strength. In the films, these transitions may lead to a large absorption coefficient. One absorption band appears that cannot be identified on the basis of the symmetry properties of the bulk material. The observed absorption spectra may be explained, however, if some of the cations have one of the following symmetry point groups: 4, 422, and 32. The Faraday rotation spectra show that: (1) the magnetic disorder increases when the oxygen to argon ratio is increased, (2) the disorder influences the cations on both tetrahedral and octahedral sites of the spinel structure.

Faraday rotations of the BaCoxTixFe12-2xO19 (0 ≤ x ≤ 0.8) hexagonal ferrite films, prepared by the dip-coating method, were measured in the range from 500 to 2500 nm at room temperature. Spectra of cobalt and titanium doped ferrite films showed local extrema at 625, 750, 1475 and 1725 nm which are due to the presence of Co2+ in tetrahedral positions.

physica status solidi (a)Volume 135, Issue 1 p. K41-K44 Short Note Effect of Experimental Errors on the Determination of Optical Constants of Thin Films L. Stichauer, L. Stichauer Laboratoire de Minéralogie-Cristallographie et Physique Infrarouge, U.R.A. C.N.R.S. 809, Vandoeuvre Search for more papers by this authorG. Gavoille, G. Gavoille Laboratoire de Minéralogie-Cristallographie et Physique Infrarouge, U.R.A. C.N.R.S. 809, Vandoeuvre Search for more papers by this author L. Stichauer, L. Stichauer Laboratoire de Minéralogie-Cristallographie et Physique Infrarouge, U.R.A. C.N.R.S. 809, Vandoeuvre Search for more papers by this authorG. Gavoille, G. Gavoille Laboratoire de Minéralogie-Cristallographie et Physique Infrarouge, U.R.A. C.N.R.S. 809, Vandoeuvre Search for more papers by this author First published: 16 January 1993 https://doi.org/10.1002/pssa.2211350140Citations: 3 B. P. 239, F-54506 Vandoeuvre lès Nancy Cedex, France. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References 1 L. Stichauer and G. Gavoille, Phys. stat. sol. (a) 133, 547 (1992). 2 L. Harris and L. Loeb, J. Opt. Soc. Amer. 45, 179 (1955). 3 P. H. Berning, Phys. Thin Films 1, 69 (1963). 4 O. S. Heavens, Phys. Thin Films 2, 193 (1964). 5 D. B. Kushev, N. N. Zheleva, Y. Demakopoulou, and D. Siapkas, Infrared Phys. 26, 385 (1986). 6 S. Belgacem and R. Bennaceur, Rev. Phys. appl. 25, 1245 (1990). 7 H. J. Bowlden and J. K. Wilmshurst, J. Opt. Soc. Amer. 53, 1073 (1963). 8 S. N. Voevodina and A. V. Tikhonravov, Optika i Spektroskopiya 68, 927 (1990). Citing Literature Volume135, Issue116 January 1993Pages K41-K44 ReferencesRelatedInformation

The optical constants of weakly absorbing thin films, deposited on thick nonabsorbing substrates, are determined from reflectance and transmission data. The fit of the theoretical expressions with the experimental data yields a large number of values of the refractive index which become closer to each other as the ratio of the film thickness to the wavelength of the radiation increases. A new approximative method is suggested in order to overcome the ambiguity of the multiple solutions. This method is then applied to the exact determination of the refractive index, the absorption coefficient, and the thickness of a YIG film.

Spectral dependences of the optical absorption and the Faraday rotation of flux-grown BaFe11Co0.5Ti0.5O19 single crystal were measured in the visible and near infrared region. The observed behaviour was explained by two paramagnetic and one diamagnetic-like transitions. The figure of merit attains maxima at 1425 and 1700 nm rendering the magneto-optical applications possible.

The initial magnetic permeability spectra of single-crystal manganese-zinc ferrite and two titanomagnetites were measured at audio frequencies from room temperature down to 10 K. The observed maxima in the magnetic loss factor can be ascribed to the passing of the anisotropy constant through zero and to the relaxation processes connected with the presence of charge carriers in the octahedral sites of the spinel lattice. The hopping of electrons of Fe2+ and Fe3+ in octahedral positions is responsible for the relaxation mechanism