Microstructures and magnetic properties of CoPt-TiO2 nanocomposite films prepared by annealing CoPt/TiO2 multilayers

CoPt-TiO2 nanocomposite films were synthesized by rapid thermal annealing of CoPt/TiO2 multilayers. The effects of annealing temperature, annealing time, Ag addition and TiO2 volume fraction on the microstructures and magnetic properties of the CoPt-TiO2 nanocomposite films were studied. Results showed that the ordering degree of CoPt and coercivity of CoPt-TiO2 nanocomposites increased with annealing temperature. Increasing annealing time and Ag addition were able to increase the ordering degree and coercivity of CoPt. However, complete L10-ordering of CoPt at 550 °C annealing was not realized by increasing annealing time up to 30 min and Ag addition up to 30 vol.%. Increasing TiO2 volume fraction at 700 °C annealing did not lead to the change of ordering of CoPt. However, the grain structure of the films changed slightly when TiO2 volume fraction was larger than 56%. The coercivity of the film decreased slightly with the addition of TiO2.