Resonant magnetic scattering of polarized soft x rays: Specular reflectivity and Bragg diffraction from multilayers

We have measured resonant magnetic scattering of elliptically polarized soft x rays from magnetically ordered Fe/Co multilayers, tuning the photon energy across the $2p$ edges of Fe and Co. Specular reflectivity was measured for a series of angles of incidence as a function of the photon energy. Bragg diffraction was measured performing θ/2θ scans for several photon energies. In both cases, large magnetic signals were observed, up to 20% peak to peak in the asymmetry ratio. An estimate of the variation of the real part of the refractive index through the Fe L₃ edge is derived from the Bragg peak displacement versus energy.