Fig. 3: Gd-specific X-ray analysis for ∇ Gd > 0 sample.

a XRMR specular reflectivity and b asymmetry ratio (AR) data measured at the Gd L3-edge for the ∇ Gd > 0 sample, where solid black lines represent the best-fitting model. c Structural scattering length densities (SLD) (red dots) obtained from the best-fitting simulation, plotted alongside the Gd composition profile (blue squares) from SIMS as a function of layer thickness.