INTERFACIAL ROUGHNESS OF PARTIALLY CORRELATED METALLIC MULTILAYERS STUDIED BY NON-SPECULAR X-RAY REFLECTIVITY

Using a two-dimensional image plate detector we measured the non-specu lar X-ray reflectivity from (Ni-0.81 Fe-0.19)/Au metallic multilayers. The image plate pattern consists of periodic diffuse sheets which ari se from the coherence of the roughness between different interfaces, a nd are strongest at the position of the Bragg peaks. We analyze the ex pression for the diffuse scattering cross-section derived from the dis torted-wave Born approximation and separate the coherent and incoheren t contributions, This allows us to determine the interface roughness p arameters, assuming it to be self-affine. From the line shape of the d iffuse sheets we determine the partial replication of the roughness fo r different length scales.