X-ray resonant magnetic scattering by Fe/Cr superlattices

We have studied the structural and magnetic properties of an antiferromagnetically (AF) coupled Fe/Cr superlattice by means of soft x-ray resonant magnetic scattering. Strong and purely magnetic Bragg peaks are observed at the half-order positions in reciprocal space parallel to the [001] growth direction and in between the structural Bragg reflections from the superlattice periodicity. The magnetic hysteresis loops measured at the first-order and at the half-order Bragg peaks clearly demonstrate the strong AF coupling of the Fe/Cr multilayer. Transverse scans and off-specular reflectivity measurements confirm an AF domain structure of the superlattice in remanence with large perpendicular correlation. In addition, the transverse scan of the half-order Bragg peak exhibits a Lorentzian line shape at zero field, which diminishes in higher fields, indicative of a remanent multidomain state approaching a single-domain state towards saturation.