Structure and magnetic properties of barium hexaferrite films deposited atlow oxygen pressures

Barium hexaferrite films were grown by pulsed laser ablation deposition ont o c-plane sapphire at oxygen pressures from 1 to 200 mTorr to evaluate thei r structural and magnetic properties. Films deposited at pressures above 1 mTorr showed excellent c-axis orientation normal to the film plane, and goo d surface morphologies. The c-axis lattice constant of films deposited at a nd above 50 mTorr was reduced compared to bulk values. Film saturation magn etization values were slightly lower than bulk values, while anisotropy hel d values were comparable. Ferrimagnetic resonance measurements showed disti nct absorption peaks, with the narrowest linewidth of 0.20 kOe being measur ed for a 10 mTorr film. The 1 mTorr film had a significantly different text ure wherein the c-axis laid down into the film plane, and also showed in-pl ane six-fold magnetic anisotropy. These results may indicate that highly c- axis oriented barium hexaferrite films can be grown to greater thicknesses using reduced oxygen pressures. (C) 2000 Elsevier Science B.V. All rights r eserved.