PHYSICAL AND MAGNETIC MICROSTRUCTURE OF RAPID THERMALLY ANNEALED THIN-FILM BISMUTH-DOPED GARNETS

Bismuth-doped iron garnets are promising materials for blue light magn eto-optic recording media. These materials have been deposited on glas s substrates with bulk magnetic and magneto-optic properties suitable for magneto-optic recording. However, these films exhibit a very low c arrier to noise ratio (CNR) when crystallized in conventional furnaces . The low CNR is due to the inability to write circular domains in the se materials. Rapid thermal annealing (RTA) has been reported to produ ce films with a much finer grain size. We have confirmed by transmissi on electron microscopy that RTA does indeed reduce the grain size over an order of magnitude from films crystallized in a conventional furna ce. Faraday microscopy has shown that films processed by RTA with smal ler grain size (approximately 30 nm) support circular magnetic domains of much greater regularity than films crystallized in conventional fu rnaces. The improved regularity of static thermomagnetically written d omains, in films crystallized by RTA, lends promise that the noise in these materials can be reduced.