Morphological study of cobalt aggregates in magnetic multilayers by grazing-incidence small-angle X-ray scattering

There has been a lot of interest in small magnetic particles for a number of years. Recently, tunnel magnetoresistance (TMR) effects have been shown in Co/Al2O3 granular multilayers, where the cobalt aggregates are embedded in an insulating nonmagnetic matrix. These effects depend strongly on the size and spacing of the aggregates. In order to characterize the morphology of the aggregates and their organization in the multilayer, we used the small-angle X-ray scattering technique under grazing incidence (GISAXS). The experiments are then carried out at/or near the critical angle. The result is a considerably enhanced surface sensitivity. It is then possible to determine the sizes of the aggregates which are found to be in very good agreement with transmission electron microscopy (TEM) results. Furthermore, the correlations in the plane of the layers and the cross-correlations from layer to layer can be determined. (C) 1998 Elsevier Science S.A.