Measurement of roughness and diffuseness of interfaces

We propose a simple formalism which allows the separation of the contributions, due to roughness and chemical interdiffusion, to the total width of an interface by using two-dimensional information from either images or chemical maps. A definition is also proposed for the roughness of an interface in terms of iso-concentration surfaces. The formalism is based on the relation between projection in real space and the corresponding section in Fourier space, the main hypotheses being that the interface roughness is isotropic and that the composition profile is constant along the interface. The method, although general, will be illustrated with results on Fresnel imaging of Cu–Co magnetic multilayers.