MICROSTRUCTURAL INVESTIGATIONS OF BI DOPED FE GARNET THIN-FILMS FOR MAGNETOOPTICAL RECORDING

Gd1.6Bi1.4Fe3.8Ga1.2012 garnet films for short wavelength magneto-opti cal recording are investigated. These films have high Faraday rotation (up to 1.3-degrees/mum), good corrosion resistance and good magnetic properties (H(c) > 1 kOe with hysteresis loop squareness of 1) but poo r noise performance. This paper shows that the noise is a result of th e grain size being of the order of the recorded domain size and that t he grain size and distribution are determined by the initial density o f garnet nuclei. In the course of this study, it was discovered that t hese films contain a high density of Bi globules which precipitate out of the garnet matrix. It is believed that these globules contribute t o the high coercivity of sputtered garnet films.