Structural, magnetic and magneto-optical properties of SrFe 12− xAl xO 19 hexaferrite thin films prepared by laser ablation deposition

Abstract

Pulse laser ablation deposition is used to produce thin films of SrFe 12− x Al x O 19 hexaferrites, with x in the interval 0≤ x≤4. The structural, magnetic, optical and magneto-optical properties of the films are investigated using XRD, AFM, MFM, VSM, transmission photometry and spectroscopic Faraday polarimetry. The films exhibit smooth optical surface and strong perpendicular anisotropy due to the almost complete texture with the c-axis normal to the film plane. The values of the film lattice constant, c, anisotropy field, H A, and magnetic anisotropy, K, are found to be very close to those of the corresponding bulk material. Absorption, Faraday rotation and ellipticity spectra of SrFe 12− x Al x O 19 hexaferrite films are determined over the spectral range 300–2000 nm and analysed in terms of the microscopic dielectric tensor theory. Six paramagnetic lines and two diamagnetic lines are identified and assigned to specific electron transitions. Furthermore, the fractional magnitudes of prominent extrema of the Faraday rotation spectra are examined as functions of Al 3+ concentration to obtain an insight into the mechanism by which Fe 3+ cations contribute to the MO spectra of M-type hexaferrites.