Pulsed Laser Deposited Barium Ferrite Films with Low Ferromagnetic Resonance Linewidths - Plume Position as a Global Property Control Parameter

High anisotropy low loss hexagonal M-type barium ferrite (BaM) thin film materials are promising candidates for use in MMIC devices such as circulators and isolators. The films are prepared by standard PLD and post-deposition annealing techniques. While progress has been made in the PLD growth of such films, there is a wide variance in ferromagnetic resonance (FMR) linewidths and film quality in general. The purpose of this work is to extend the existing map to include new data on the FMR linewidth as a function of oxygen partial pressure, target-substrate distance, laser energy, the lateral substrate-plume displacement, and post-deposition annealing temperature. It is found that the effects of these parameters on the linewidth are interrelated. The 60 GHz FMR peak-to-peak derivative linewidth ranged from 21 to 1000 Oe. This result suggests that small plume sizes will compromise the loss properties of large area films substantially, and that large laser beam areas and larger plumes will be needed for such films.