Large coercivity of 13 kOe in L1₀-ordered CoPt on Si/SiO₂ substrates by hydrogen annealing

Abstract L10-ordered CoPt with a large coercivity (Hc) of 13 kOe was demonstrated on Si/SiO2 substrates by hydrogen annealing. Equiatomic 11.2-nm-thick (Co/Pt)4 multilayer thin films were fabricated by electron-beam evaporation and were annealed at 500–900 °C for 10–90 min under an Ar/H2 mixed gas atmosphere. The annealing temperature and time dependences of the crystal structures, magnetic properties, and surface morphologies of the films were systematically analyzed based on the experimental results obtained from grazing incidence X-ray diffraction, vibrating sample magnetometer, and scanning electron microscope, respectively. Hydrogen annealing effectively promoted the out-of-plane c-axis orientation of L10-CoPt compared to the vacuum annealing according to the GI-XRD patterns. A maximum Hc of 13.3 kOe was obtained in L10-ordered CoPt with angular-outlined isolated grains by hydrogen annealing at 800 °C for 60 min, where the c-axis of L10-ordered CoPt was randomly distributed.