X-ray diffraction study of laser-driven solid-state diffusional mixing and new phase formation in Ni-Pt multilayers

An in situ optical pump and x-ray probe technique has been utilized to study photoinitiated solid-state diffusion in a Ni-Pt multilayer system. Hard x-ray diffraction has been used to follow the systematic growth of the NiPt alloy as a function of laser intensity and total energy deposited. It is observed that new phase growth can be driven in as little as one laser pulse, and that repeated photoexcitation can completely convert the entire multilayer structure into a single metallic alloy. The data suggest that lattice strain relaxation takes place prior to atomic diffusion and the formation of a NiPt alloy.