THE EFFECTS OF SUBSTRATE-TEMPERATURE AND OXYGEN-PRESSURE ON PULSED-LASER DEPOSITED BISUBSTITUTED DY IRON-GARNET FILMS

Polycrystalline thin films of highly Bi substituted Dy iron garnets, [ (BixDy3-x(Fe, Ga)(6)O-12], with [111] crystalline orientation perpendi cular to the film plane were grown on (111) Gd3Ga5O12, single crystal substrates using pulsed laser deposition technique. In the deposited f ilms, Bi stoichiometry was found to be very sensitive to both substrat e temperature and oxygen pressure. The Bi volatilisation problem was r elieved by depositing in a high background pressure of oxygen. The res ults demonstrated that high quality garnet films with large magneto-op tical (MO) effects and square hysteresis loops could be obtained when the substrate temperature did not exceed 590 degrees C and the oxygen pressure was kept in the neighbourhood of 0.2 mbar. The MO behaviour o f these films compared well with predictions based on the fundamental constants of Bi substituted Yttrium Iron Garnet thick films, grown by liquid phase epitaxy. The coercivity could be varied from a few hundre d Oe to several kOe by controlling the oxygen pressure and film thickn ess.