The origin of a magnetic anisotropy of the order of 10⁷ erg/cm³ observed in Co₃Pt alloy thin films deposited onto Al₂O₃(00·1) substrates is investigated. The magnetic anisotropy constant K_u increases with the substrate deposition temperature T_s, which exhibits a maximum at T_s ≈ 400°C. The Co₃Pt ordered phase is found to exist in these films. The order parameter S estimated by X-ray diffraction reaches a maximum at T_s ≈ 400°C. The behaviors of K_u and S with respect to T_s are similar when T_s is greater than about 380°C. The samples show a larger K_u with higher S. However, K_u still remains 10⁷ erg/cm³ at S=0. Both K_u and S can be enhanced by reducing the deposition rate at T_s ≈ 330°C. On the basis of these experimental results, a model is proposed to account for the dependence of K_u on S. In this model, the observed K_u is assumed to include two components of the disordered and ordered phases. The contributions of the disordered and ordered phases to the total magnetic anisotropy can be reasonably well quantified on the basis of the model.

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Magneto-optical (MO) figure-of-merit parameters of localized modes in one-dimensional magnetophotonic crystals (1D-MPC) with bismuth-substituted yttrium iron garnet (Bi:YIG) film were studied numerically by using the matrix approach based on the 4 × 4 matrix formalism. The structure of 1D-MPC is expressed as (SiO₂/SiN)^R/Bi:YIG/(SiN/SiO₂)^R with the stacking number R, where the Bi:YIG interlayer acts as a defect supporting the magneto-optically active localized modes. The study revealed that the localized modes exhibit large figure-of-merit parameters with very thin Bi:YIG layers; for instance, when R = 10 and d_M (Bi:YIG thickness) = 0.15 μm, the first localized mode at λ ≈ 650 nm exhibits T (transmissivity) ≈ 50% and θ_F (Faraday rotation) = -6 deg., resulting in a figure-of-merit of Q_F = T^1/2|θ_F| ≈ 4 deg. for the Faraday operation, while the localized mode shows R (reflectivity) ≈ 8% and θ_K (Kerr rotation)=16 deg., yielding Q_K=R^1/2|θ_K| ≈ 4.5 for the Kerr operation. These results strongly indicate that the 1D-MPC structure is very effective for realizing large figure-of-merit parameters (comparable to those of Bi:YIG bulk materials) by using very thin Bi:YIG layers.

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