Depth resolved x-ray absorption fine structure study in magnetic multilayers using x-ray standing waves

Abstract

X-ray standing waves generated using total external reflection from Au buffer layer has been used to get information about the structure of the interfaces in a Tb∕Fe∕Tb trilayer. X-ray absorption fine structure (XAFS) measurements done under standing wave conditions have sufficient depth resolution in order to differentiate the center of the Fe layer from the interfacial region. XAFS measurements are done in two geometries, with plane of polarization of the incident x-ray lying either in the film plane or perpendicular to it. In these two geometries information is obtained about the bonds lying in the film plane or perpendicular to it, respectively. These measurements provide clear evidence that Fe–Tb bonds in the interfacial region lie preferentially normal to the film plane. This asymmetry of Fe–Tb bonds is the cause of perpendicular magnetic anisotropy in the system. Present studies demonstrate that use of x-ray standing waves can provide sufficient depth resolution in order to elucidate the interface structure in magnetic multilayers.