Reflectivity and diffraction study of cross-beam pulsed laser deposited Co/Cu multilayers

Abstract

Co/Cu multilayers were prepared by cross-beam pulsed laser deposition and characterised by high-angle X-ray diffraction as well as specular and off-specular reflection. Using synchrotron radiation at the K-edge energy of Co and Cu to enhance the scattering contrast, the study shows that the roughness of these multilayers is well described by the fractal model of self-affine structures. For the pulsed laser deposited layers an extremely large lateral correlation length, ξ, of the vertically correlated interfacial roughness is found (ξ>1 μm) which exceeds the ξ-value of the uncorrelated roughness by approximately two orders. The interfaces are very jagged (roughness exponent, h, between 0.15 and 0.3). The root mean square roughness, σ r.m.s., of the Cu/Co and Co/Cu interfaces are of the same order compared with the values reported for sputtered layers.