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

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Abstract
Garnet films of composition R3−x−yPrxBiyFe5O12 with R=Lu, Y, and 0≤x≤1.8, 0≤y≤1.7 have been grown from different melt compositions and under various growth conditions onto substituted gadolinium gallium garnet substrates with (100), (110), (111), and (211) orientation. The dependence on composition and temperature of the saturation magnetization Ms, the uniaxial anisotropy constant Ku, the Faraday rotation θF, and the Faraday ellipticity ψF, have been investigated. The change of Ms as compared to that of Y3Fe5O12 is essentially associated with the alignment of the Pr moment parallel to the net iron moment and the increase of the Curie temperature originating mainly from the bismuth. However, both contributions are negligible in the room‐temperature range. The uniaxial anisotropy is strongly affected by both Pr and Bi. The anisotropy contributions ΔKu /x0 turn out to be approximately additive. Both Pr and Bi give rise to a pronounced enhancement of the magneto‐optical effects. At λ=633 nm θF increases linearly with x and y yielding at T=295 K the contributions ΔθF/x =−3.8×105 deg m−1 and ΔθF/y=−20.6×105 deg m−1, respectively. The bismuth contribution compares well with that observed for various other Bi‐substituted rare earth iron garnets.