Observation of nearly intrinsic ferromagnetic resonance linewidth in BaFe12O19 films deposited by pulsed laser deposition

We report magnetic resonance results on (0.3-8 mum) Mms of c-axis oriented barium ferrite grown by pulsed laser deposition on sapphire substrates. By optimizing the growth and annealing parameters, we have observed numerous (up to 25) spin wave resonance modes as well as nearly intrinsic ferromagnetic resonance linewidth of 23 Oe at 58 GHz, when the applied field is parallel to the c axis. On rotation of the field away from the film normal, the linewidth increases rapidly. This is taken in to account by using a small (0.3 degrees) spread in the film orientation combined with the conventional formula for shape anisotropy. Atomic force microscopy surface roughness measurements support these considerations.