Structure, magnetic, and microwave properties of thick Ba-hexaferrite films epitaxially grown on GaN/Al2O3 substrates

Thick barium hexaferrite [BaO center dot(Fe2O3)(6)] films, having the magnetoplumbite structure (i.e., Ba M), were epitaxially grown on c-axis oriented GaN/Al2O3 substrates by pulsed laser deposition followed by liquid phase epitaxy. X-ray diffraction showed (0,0,2n) crystallographic alignment with pole figure analyses confirming epitaxial growth. High resolution transmission electron microscopy images revealed magnetoplumbite unit cells stacked with limited interfacial mixing. Saturation magnetization, 4 pi M-s, was measured for as-grown films to be 4.1 +/- 0.3 kG with a perpendicular magnetic anisotropy field of 16 +/- 0.3 kOe. Ferromagnetic resonance linewidth, the peak-to-peak power absorption derivative at 53 GHz, was 86 Oe. These properties will prove enabling for the integration of low loss Ba M ferrite microwave passive devices with active semiconductor circuit elements in systems-on-a-wafer architecture. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3446867]