Effects of Ag buffer and Pt intermediate layers on magnetic properties of epitaxial Co/Pt multilayers

Co/Pt multilayers were prepared on silicon substrates with a Ag buffer of different thickness and Pt intermediate layers by using the molecular-beam epitaxial technique. The as-deposited films (at 160°C) were then post-annealed for 30 min in a vacuum at a temperature (T_an) ranging from 260°C to 500°C. The formation of CoPt L1₀-ordered structure were observed for all the samples grown at 160°C. The out-of-plane coercivity (Hc_⊥) and saturation magnetization (Ms_⊥) of all Co/Pt multilayer films decreased monotonically as elevating annealing temperature, owing to the heavy diffusion of Si into Co/Pt films at higher temperatures. When T_an reaches 500°C, the formation of PtSi phase destroys the magnetic properties.