  The ion-sputtering induced intermixing is studied by Monte-Carlo TRIM,
molecular dynamics (MD) simulations, and Auger electron spectroscopy depth
profiling (AES-DP) analysis in Pt/Ti/Si substrate (Pt/Ti) and Ta/Ti/Pt/Si
substrate (Ti/Pt) multilayers. Experimental evidence is found for the asymmetry
of intermixing in Pt/Ti, and in Ti/Pt. In Ti/Pt we get a much weaker
interdiffusion than in Pt/Ti. The unexpected enhancement of the interdiffusion
of the Pt atoms into the Ti substrate has also been demonstrated by
simulations. We are able to capture the essential features of intermixing using
TRIM and MD simulations for ion-beam sputtering and get reasonable values for
interface broadening which can be compared with the experimental measurements.
However, the origin of the asymmetry remains poorly understood yet.
