Ferrimagnetic resonance linewidths of thick barium hexaferrite films on MgO (111)

C-axis oriented barium hexaferrite films having thickness from 3-30 μm were deposited onto 0.5 mm magnesium oxide (MgO) (111) substrates by pulsed laser ablation deposition, and were characterized by magnetometry and ferrimagnetic resonance (FMR) measurements. The FMR linewidth for as-produced 30 μm films was 0.65-0.70 kOe, while those of thinner (3 μm) films was near 0.50 kOe. The narrowest linewidth of ~0.06 kOe was obtained for a 3 μm film after annealing for two hours. However, increased annealing time beyond two hours caused an increase in FMR linewidth. The FMR linewidth of 30 μm films where from 55-77% of the MgO substrate was removed decreased by 0.15-0.20 kOe compared to as-produced films. Further improvement in the FMR linewidth to 0.20 kOe was obtained by a two hour annealing. These FMR results are discussed in terms of the homogeneity, planar stress, and stoichiometry of these thick pulsed laser deposited films