K. Sahl

Crystallographic and magnetic investigation on W-type-hexaferrite single crystals in the solid solution series SrZn 2-x Co x Fe 16 O 27

The saturation magnetization and the magnetocrystalline anisotropy were measured on single crystals in the solid solution series SrZn 2-x Co x Fe 16 O 27 (SrZn 2-x Co x -W) at 298 K and 6 K. Lattice constants and Curie-temperatures are also given as a function of the composition. The magnetocrystalline anisotropy changes from uniaxial to planar dependent on temperature and cobalt substitution at x \approx 0.5 for 6 K and x \approx 0.85 for 298 K. The six-fold anisotropy in the basal plane of the planar W-hexaferrites increases strongly with increasing cobalt content. Crystals with a low Co substitution (x = 0.33 and 0.67) have an anomalous discontinuity in their hard direction magnetization curves; indicating a first-order magnetization process.

Preparation and magnetic properties of LPE-grown hexagonal strontium aluminoferrite films

Abstract Continuous monocrystalline films of ferrimagnetic SrFe 8 Al 4 O 19 with thicknesses between 3 and 10 microns were grown by liquid-phase epitaxy on single-crystal substrates of nonmagnetic, transparent SrGa 12 O 19 . Layer and substrate both have the same magnetoplumbite type crystal structure. The crystallographic, chemical and magnetic properties of the layers are reported; quantitative measurements of the magnetic properties of the films are compared to literature values for bulk crystals of the same chemical composition.

Flux growth of SrGa12O19 single crystals

Abstract Flux growth and some properties of SrGa 12 O 19 single crystals are reported. Li 2 MoO 4 , Na 2 MoO 4 and Bi 2 O 3 were tried as flux components using the slow cooling technique. Only Bi 2 O 3 proved to be suitable. Systematic variation in the proportion of starting compounds (SrCO 3 , Ga 2 O 3 , Bi 2 O 3 ) revealed an optimal starting composition (17.5 mole% SrCO 3 , 52.5 mole% Ga 2 O 3 and 30 mole% Bi 2 O 3 ). Tabular SrGa 12 O 19 crystals up to several mm in diameter were obtained. Chemical, optical and X-ray investigations showed them to be useful substrates for LPE of magnetic hexaferrite layers with magnetoplumbite or related lattice.

Epitaxial growth and properties of strontium hexaaluminoferrite layers

Abstract The growth of (Sr, Pb)(Fe, Al) 12 O 19 layers on SrGa 12 O 19 and SrAl 12 O 19 substrates is reported. SrGa 12 O 19 single crystal substrates were grown by directional solidification of a melt containing excess SrO. SrAl 12 O 19 single crystals were obtained by the flame-fusion technique. Layers of composition SrFe 8 Al 4 O 19 were deposited upon substrates by evaporation of PbF 2 used as solvent on the heating stage of a microscope. This procedure yielded a continuous overgrowth on SrGa 12 O 19 (no misfit between layer and substrate material) and discontinuous islands on SrAl 12 O 19 (linear misfit of 4%). The magnetic properties of the layers (T C , M S ) correspond to those of bulk SrFe 8 Al 4 O 19 material.

LPE-grown hexagonal strontium aluminoferrite films

Continuous monocrystalline films of ferrimagnetic SrFe 8 Al 4 O 19 were grown by liquid phase epitaxy on single-crystal substrates of non-magnetic transparent SrGa 12 O 19 . Layer and substrate both have the same magnetoplumbite type crystal structure. Static magnetic properties of the layers compared to literature values for bulk crystals of the same chemical composition are reported. They provide evidence for potential applications in the bubble domain technique and microwave and millimeter-wave devices.