Contrast variation by anomalous X-ray scattering applied to investigation of the interface morphology in a giant magnetoresistance Fe/Cr/Fe trilayer

The structural properties of an epitaxically grown Fe/Cr/Fe trilayer were studied with anomalous X-ray scattering. Two different X-ray energies have been used: (i) E₁ = 5985 eV to match the maximum contrast of the Fe/Cr interface close to the Cr absorption K edge; (ii) E₂ = 6940 eV where the Fe/Cr interface displays the lowest contrast. The specular reflectivity and longitudinal diffuse scans together with ω scans for both energies were measured. The simulations within the frame of the distorted-wave Born approximation allowed a quantitative description of the morphology of each interface. The roughness, Hurst parameter and the thickness of every layer, as well as an oxidation effect at the surface of the sample, are derived. The strength and limitations of the method are discussed.