S. Díaz-Castañón

Oriented PbFe12O19 thin films prepared by pulsed laser deposition on sapphire substrate

Abstract PbFe12O19 hexaferrite thin films with a high degree of orientation in the perpendicular direction have been deposited by pulsed laser ablation on 1×1-cm2 (0001) sapphire substrate at 700°C under 3.0 mbar partial pressure of high purity oxygen. The anisotropic character of the films was demonstrated by a remanence ratio of 86% in the perpendicular direction in contrast with to 20% in the parallel direction to the film plane. The X-ray diffraction analysis confirmed this orientation, showing only the (0001) lines of PbFe12O19 compound. The hexagonal lattice parameters determined were a=5.885 A and c=23.066 A. Moderate values of coercive field (2.5 kOe) and saturation magnetisation (165 emu/cm3) were obtained.

Mössbauer and magnetic investigation of scandium and indium substituted PbFe12O19 hexagonal ferrite

Magnetic and Mössbauer measurements have been performed on polycrystalline substituted M-type hexagonal ferrites of compositions PbFe12−xScxO19 (x = 0, 0.5, 1, 1.5) and PbFe12−xInxO19 (x = 0, 1, 2). The substitution of the Fe3+ by Sc3+ and In3+ ions perturbs the axial magnetic order giving rise to angled magnetic structures. From the values of the quadrupole splitting of the Fe57 14.4 keV level, measured above and below the Curie temperatures, the angle between the magnetic moment of the Fe3+ ions in various sublattices and the hexagonal c-axis have been deduced. At 77 K the measured angles do not exceed 20° and depending on x are different for different sublattices. The dependence of x on the saturation magnetisation at 0 K, expressed in Bohr magnetons, differs markedly in Sc and In containing compounds, partly due to the different substitution probability of iron in the spin up and spin down sublattices, and also due to the different spin canting angles.

Magnetic and Mössbauer investigation of Sc- and In-substituted PbFe12O19 hexaferrites

Abstract PbFe 12 − x Me x O 19 , Me = Sc, In (0 ⩽ x ⩽ 3), hexaferrites have been characterised by vibrational sample magnetometry and Mossbauer spectroscopy in the temperature range 77–800 K. For both series, the saturation magnetisation and the Curie temperature showed a rapid fall with the substitutions. It was also established that In and Sc ions enter the pseudohexahedral sublattice b with the same probability as for other lattice sites.