Magnetic structure of Fe/Gd multilayers determined by resonant x-ray magnetic scattering

The magnetic structures of a (Fe/Gd)(15) multilayer are determined by reson ant x-ray magnetic scattering using circular polarized light of energies tu ned close to the Gd L and the Fe K absorption edges. Difference superlattic e Bragg peaks observed by flipping the photon helicity show that the magnet ic moments of the Gd layers are directed antiparallel to the in-plane appli ed held at temperatures higher than 180 K, and are twisted below. The local Gd magnetizations in each 5.4-nm-thick layer are highly nonuniform in both magnitude and twist angle in the out-of-plane direction: the interface sub layers nearly fully magnetize at room and low temperatures under the influe nce of the adjacent Fe magnetizations, whereas the central sublayers show m easurable spontaneous magnetizations at 200 K and below. An application of the 1 -(T/T-c) law shows a reduced Curie temperature (T-c=214 K) compared w ith bulk Gd for the central sublayers, while T-c= 1023 K for the interface sublayers. The interface and central sublayers exhibit distinct twist behav iors as a function of temperature below the compensation temperature, indic ating the short-range nature of the Fe-Gd interaction. The element-specific resonant x-ray scattering confirmed the antiferromagnetic arrangement of t he Gd and Fe moments at room temperature.