Magnetic properties of liquid-phase epitaxial films of Y3−xGdxFe5−yGayO12 for optical memory applications

The effective uniaxial magnetic anisotropy field Heff = 1/6 (2 Ku/Ms – 4 π Ms) in liquid-phase epitaxial garnet films of the approximate chemical composition Y2.4Gd0.6Fe3.7Ga1.3O12 has been studied as a function of the mismatch between the lattices of the substrate and the film. Heff is found to exhibit a distinct singularity at the compensation temperature Tcomp, which is about +30°C in these films. A temperature increase ΔT0 = T0 – Tcomp above Tcomp where Heff becomes negative is required to render the alignment of the magnetization M vertical to the film plane instable. ΔT0 is shown to vary linearly with the mismatch. The applicability of such films for a magnetooptic memory is briefly discussed.