RF sputtered films of Bi-substituted garnet for magneto-optical memory

Bi-substituted Ga:YIG and Ga:DyIG films have been prepared on glass substrates by rf sputtering and post annealing. Large additions of Bi to the film steeply reduced the crystallization temperature Tcry. to yield single phase garnet; Tcry. is 520°C for Bi content over 2.5 ions per formula unit. Sputtering in pure Ar instead of an Ar-O
2
mixture improved the optical and magnetic homogeneity of the films by reducing grain boundary segregation. Films sputtered in Ar also exhibited Faraday hysteresis loops with good squareness and high coercivity. These are explained in terms of oxygen deficiency introduced in the film during deposition.