Magnetic and Magneto-Optical Properties of Nano - Multilayer Thin Films
Structural, magnetic and magneto-optical properties were investigated experimentally in nanostructured rare earth/Fe (rare earth=Gd, Tb, Dy), Co/Pt and Bi-doped DIG/T (T=Fe, Co, Dy and DIG=Dy-Iron-Garnet) multilayer thin films. In the rare earth/Fe system, it was found that the magnetization reversal could be correlated with the intrinsic magnetic parameters, especially the perpendicular magnetic anisotropy. It was found that higher anisotropy leads to magnetization reversal primarily by domain wall motion due to the higher domain wall energy. The coercivities of these multilayers were strongly dependent on the temperature as well as magnetic field sweep rate, and a strong magnetic after effect was observed. These results demonstrate that thermal activation plays an important role in the determination of the coercivity. The coercivity of Co/Pt multilayer thin films increases with increasing total thickness of the film and magnetization reversal behavior was largely by wall motion, independent of thickness. However the magnetic domain structure depends strongly on the total thickness, presumably due to subtle differences in the defect structures which pin domain walls. In agreement with other studies, it was found that magnetic polarization of the Pt atoms contributed significantly to the total magnetization and Kerr rotation at blue wavelength. Amorphous DIG/Fe multilayer films were prepared by magnetron sputtering, and subsequently crystallized by rapid thermal annealing. The resulting films had small grain size (down to 10 nm) so that they are appropriate materials for magneto-optical storage applications. Depending on the Bi composition, Faraday rotation of up to 15 degrees/ μm was observed. Domain wall expansion into maze-like domains dominated the reversal process. The dielectric constant tensors, including the off-diagonal component responsible for magneto-optical activity, are reported for several samples.
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- AMORPHOUS FILMS;
- Physics: Condensed Matter