Ti underlayer effect on the ordering of CoPt in (Co/Pt)4 multilayer thin films on Si/SiO2 substrates

Abstract

Abstract L12-ordered CoPt3 and L10-ordered CoPt are formed in electron-beam-deposited (Co/Pt)4 multilayer thin films with and without a Ti underlayer, respectively, on Si/SiO2 substrates by rapid thermal annealing. The crystal structures, magnetic properties, and surface morphologies of the films are investigated by grazing incidence X-ray diffraction (GI-XRD), vibrating sample magnetometer (VSM), and scanning electron microscope (SEM), respectively. In the film without a Ti underlayer, L10-ordered CoPt with an isolated round grain structure is confirmed, showing an in-plane coercivity of 2.7 kOe. In contrast, in the film with a Ti underlayer, L12-ordered CoPt3 is confirmed together with Co-rich A1-disordered CoPt, showing an in-plane coercivity of 500 Oe, which exhibits an angular-outlined continuous film structure. The three sets of experimental results from GI-XRD, VSM, and SEM coincide well with each other.