SPECULAR AND OFF-SPECULAR ANOMALOUS X-RAY-SCATTERING AS QUANTITATIVE STRUCTURAL PROBES OF MULTILAYERS

We have refined experimental techniques and developed theoretical anal yses which allow a quantitative structural characterization of multila yers through X-ray diffraction. The use of both specular and off-specu lar measurements has provided probes of sample structure in the vertic al (growth) direction and in the horizontal (parallel to interfaces) d irection. In addition, by performing small-angle as well as large-angl e diffraction measurements, both mesoscopic and atomic length scales a re accessible. The advantages of high intensity and anomalous dispersi on available with synchrotron radiation (LURE, Orsay) have greatly con tributed to the quality of our data, for which the use of simulation p rograms has allowed a robust and precise extraction of several structu ral parameters, such as layer thicknesses, interfacial thicknesses, an d interfacial correlation lengths. We have obtained results for a vari ety of samples, including several Fe/Ir and Mn/Ir superlattices (grown at different temperatures), three Fe/Pd superlattices (having control led interface profiles), and a monolayer of SiO2 grown on Si through d ry oxidation. In this paper we present some representative results. Th e physical properties of such multilayer materials (e.g. magnetic and transport properties) are generally very dependent on their structural characteristics, in particular their interfacial structures.