Bi-substituted garnet films sputtered in Ar + H2 for magneto-optic memory.

To investigate properties of Bi-substituted garnet film with many oxygen deficiencies, Bi, Ga:DyIG films were prepared by sputtering in Ar + H2 gas (H2 partial pressure 0 to 5%), and then annealed to promote crystallization. When the H2 concentration in the sputtering gas was raised, the Bi content of the film decreased. The film sputtered in Ar + H2 crystallized as a single garnet phase at relatively low temperatures (560°C for Bi = 1.5), even when the Bi content was low, under nonstoichiometric conditions. The optical homogeneity of the film improved greatly when the H2 concentration was raised; optical scattering due to crystal gain boundaries was reduced below that of film sputtered in pure Ar gas.