X-RAY AND MAGNETORESISTANCE MEASUREMENTS OF ANNEALED CO CU MULTILAYERS/

Annealed Co/Cu multilayers grown on sapphire by molecular beam epitaxy have been studied by grazing-incidence X-ray scattering and magnetotr ansport measurements. Specular X-ray reflectivity data indicated no ch ange in interface roughness for these multilayers grown on Nb buffer l ayers on sapphire. This was confirmed in extensive diffuse scattering studies. Exploiting the tunability of synchrotron radiation, we have u sed anomalous dispersion to highlight the Co/Cu interfaces from those associated with the buffer and cap layers. This has shown that virtual ly all of the Cu/Co interface roughness is correlated through the mult ilayer. No change in the correlated roughness occurred on annealing, b ut monotonic rises in both the resistivity rho and Delta rho were obse rved which scaled such that little change occurred in the GMR. We expl ain the large changes in resistivity as the result of alloying between the top Cu layer of the multilayer and the Au cap.