Large coercivity of 13 kOe in L1(0)-ordered CoPt on Si/SiO2 substrates by hydrogen annealing

L1(0)-ordered CoPt with a large coercivity (H (c)) 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 degrees C-900 degrees C for 10-90 min under an Ar/H-2 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 (GI-XRD), vibrating sample magnetometer, and scanning electron microscope, respectively. Hydrogen annealing effectively promoted the out-of-plane c-axis orientation of L1(0)-ordered CoPt compared to the vacuum annealing according to the GI-XRD patterns. A maximum H (c) of 13.3 kOe was obtained in L1(0)-ordered CoPt with angular-outlined isolated grains by hydrogen annealing at 800 degrees C for 60 min, where the c-axis of L1(0)-ordered CoPt was randomly distributed.