STATIC MAGNETIC AND MICROWAVE PROPERTIES OF LI-FERRITE FILMS PREPAREDBY PULSED-LASER DEPOSITION

Highly textured Li-ferrite films have been synthesized by pulsed laser deposition from bulk targets onto c-plane sapphire substrates. For su bstrate temperatures approaching 1000 degrees C the growth mode was pr edominantly (333). A similar growth mode was recently reported for Ni- ferrite films grown onto c-plane sapphire substrates. The films were 4 -8 mu m thick and were grown at deposition rates of 3-5 Angstrom/s at oxygen partial pressures of 200-400 mTorr. Magnetic measurements were made by SQUID and 9.5 GHz ferromagnetic resonance (FMR) on the as depo sited films. Textured Li-ferrite films with x-ray diffractometer inten sity ratios of I(333)/I(311) = 10.3 for films made in 200 mTorr oxygen and 14.5 for films made in 400 mTorr oxygen exhibited room temperatur e in-plane intrinsic coercivities of <100 Oe for SQUID magnetometer me asurements. Highly (333) textured Li-ferrite films made in 400 mTorr o xygen exhibited clean symmetric FMR absorption lines with a derivative peak-to-peak linewidth of 335 Oe for the in-plane static field config uration. The FMR profiles for the perpendicular-to-plane field configu ration were highly distorted. The magnetization versus field measureme nts and the in-plane FMR field position yielded saturation flux densit y 4 pi M-s and effective saturation flux density 4 pi M-eff values of 3.6-4.0 kG and 3.56-3.70 kG, respectively. These values are in the sam e range as for bulk Li-ferrite. The in-plane FMR linewidths were signi ficantly larger than expected for bulk single crystals or large grain size, dense polycrystals. (C) 1997 American Institute of Physics.