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Microstructure and magneto-optical properties of cobalt-based magnetic multilayered films
Abstract
Cobalt-based multilayer thin films such as Co/Pt and Co/Pd were prepared by magnetron sputtering and electron-beam evaporation. The individual layer thickness for magnetic Co layers was typically 2 to 10A, and that of the nonmagnetic layers 10 to 20A. Physical properties such as crystallinity, magneto-optical Kerr effect, optical, and magnetic properties of these films were studied using a variety of techniques. Systematic studies on crystalline structures of multilayers showed that for multilayers consisting of ultra-thin sublayers, the chemical composition of the films is modulated as shown by small angle x-ray diffraction. However, crystalline structures are not modulated for multilayers consisting of ultrathin sublayers (less than 20A thick). This point was clearly shown by x-ray diffraction data from these multilayers. Sputtering pressure has significant effects on the quality of multilayer films. Low sputtering pressure yields smooth film surface with sharp interfaces, while high sputtering pressure results in more diffuse interfaces. The surface roughness of samples was also studied using atomic force microscopy and ellipsometry. The magneto-optical Kerr effect (MOKE) of Co/Pt and Co/Pd multilayers was investigated. It has been found that the Pt underlayer has a great effect on crystallinity, but has almost no effect on magnetic coercivity. Optical interference has been observed due to the Pt underlayer. The Kerr rotation reaches a maximum in the optical range (3000 to 8000A). For samples with thin Co layers (less than 4A), the direction perpendicular to film surface is the magnetic easy axis. The coercivity of electron-beam evaporated Co/Pt multilayers is always larger than similar sputter-deposited multilayers. Typically, coercivity is in the range from 100Oe to 2500Oe, depending on layer structures and sputtering pressure. Thermal stability of Co/Pt multilayers was also studied using vacuum annealing. It was found that layered structures and crystalline structures are stable up to about 300$\sp\circ$C.
Subject Area
Condensation|Optics|Materials science
Recommended Citation
He, Ping, "Microstructure and magneto-optical properties of cobalt-based magnetic multilayered films" (1993). ETD collection for University of Nebraska-Lincoln. AAI9331418.
https://digitalcommons.unl.edu/dissertations/AAI9331418