Electrodeposition of (001) oriented CoPt L10 columns into anodic alumina films

Anodic alumina films are known to have perpendicular holes normal to the film surface. This character is favorable to perpendicular magnetic recording and patterned media. L10-ordered CoPt columns are filled into anodic alumina nanoholes by an electrodeposition method and a subsequent thermal annealing process. Two kinds of metal (W and Pt) were used as underlayers at the bottom of nanoholes, which acts as electrode layer for electrodeposition. We show that while the embedded L10-ordered CoPt columns have random c-axis orientations for W underlayer samples, the c-axis orientation can be controlled by using the underlayer with Pt(001) surface. This orientation controlled sample has a perpendicular anisotropy with Hc=7.4 kOe, and Mr/Ms=0.96. This approach has the potential to become one of the important methods for the fabrication of recording media with ultrahigh areal density.