Magnetic and magneto-optic properties of bismuth- and aluminum-substituted iron garnet films

Abstract

The saturation magnetization Ms, the uniaxial anisotropy Ku, the optical absorption α, the Faraday rotation θF, and the Faraday ellipticity ψF of epitaxial garnet films of composition Y3−xBixFe5−yAlyO12 have been investigated for x≤1.34 and y≤2.22. The temperature dependence of Ms and θF at λ=633 nm have been measured in the range 4.2 K≤T≤TC. Ku, TC, θF, and ψF reveal a linear dependence on the bismuth content. The dependence of θF and ψF on the aluminum concentration shows that both sublattices are involved and indicate that the magneto-optical effects have to be ascribed to iron pair transitions. The magnitude of the growth-induced anisotropy is essentially controlled by the supercooling ΔTs and increases linearly with ΔTs. The obtainable magnetic and magneto-optical data for magneto-optical applications are discussed and compared with those of garnet films exhibiting a compensation temperature.