Abstract
Thin films of various kinds of hexagonal Magneto-plumbite type (M-type) ferrites as magnetic layer with Pt underlayer were prepared using flash annealing process. M-type strontium ferrite with substitution of Sr2+ and Fe3+ by La3+ and Co2+ thin films (LaCo-SrM) and M-type barium ferrite thin films (BaM) on Pt underlayer were prepared by the Facing-Targets Sputtering system. Since the grain size became huge enough because the high substrate temperature, e.g. around 500°C, is maintained particles by excess heating during the deposition. Flash-annealing technique means to anneal the specimen at high temperature above 900°C for a few moments after the deposition of the films at low temperature of 250°C enough for preventing crystallization. Annealing at 900°C for 3 minutes was an appropriate processing condition as a flash-annealing process to attain high perpendicular coercivity Hc⊥ and perpendicular squareness S⊥ ratio in case of BaM with maintaining the grain size as low as several tens nanometers. 30 nm-thick LaCo-SrM films prepared by flash-annealing at 900°C and for 5 minutes exhibited very smooth surface and small particle size about 22 nm. The film revealed large Hc and squareness of 4.5 kOe and 0.75, respectively. Flash-annealing is very useful for preparing the superior magnetic recording media.
