Enhancement of ordering and perpendicular magnetic properties of CoPt films by adding Ag underlayer

CoPt/Ag films were prepared by magnetron sputtering on glass substrates and subsequent annealing. The dependence of ordering degree and magnetic properties on Ag film thickness and annealing conditions were investigated. It was found that the Ag underlayer played a dominant role in inducing the (001) texture of the CoPt film after annealing. CoPt films with a thickness about 20 nm and Ag underlayers with a thickness about 70 nm are easy to obtain a well ordering degree and a perpendicular magnetic anisotropy after annealing at 700 °C for 30 min. CoPt/Ag films with a large perpendicular coercivity in the range of 13.5-14.0 kOe and a perpendicular squareness of 0.97 were obtained after annealing at 700 °C for 30 min. Ag underlayer is beneficial to enhance the perpendicular coercivity (Hc¿) and perpendicular squareness (S¿) of CoPt film significantly. The ordering degree and perpendicular magnetic properties of the CoPt films which deposited on Ag underlayer are larger than those of the single layer CoPt films.