X-ray reflection study of layred structures in multilayrs for magnetic recording

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Designing a practical X-ray reflectometer, we have determined the layr structures and surface/interface structures in various magnetic multilayrs. The reflectometer uses a two-axis diffractometer and asymmetric silicon channel-cut crystals for the monochromator and analyzer at a rotating-anode X-ray generator. The asymmetric Si 111 reflection used in the monochromatorprovides a three times more intense CuK alpha beam than the conventional design. For the analyzer a mechanical slit and an asymmetric channel-cut crystal can be used depending on the resolution requirement. The software correction extended the linear range of photon counting to 5*10^5 cps. The X-ray source is run at a constant output to avoid the shift of the optics setting due to the slight displacement of the X-ray focus on the rotating anode. The reflectometer is controlled by a HITACHI UNIX workstation, which allows rheta, 2rheta and rheta-2rheta scans exploring reciprocal space. Specular reflection profiles are recorded in an overnight measurement and non-specular diffuse scattering profiles can be measured in reasonably short time. The data analysis software developed uses the distorted-wave Born approximation of X-ray scattering, which allows the thickness and interface roughness of individual layrs tp be determined by least-squares fit of specular profiles. The software also includes routines to determine the intra and inter-interface correlations of the roughness structures, and the fractal dimension, from nonspecular data.