The magnetic anisotropy in the initial layer of Co-Cr sputtered thin films

Co-Cr thin films prepared using Facing Targets Sputtering (FTS) System show well c-axis orientation even at the early stage of the film growth. However, the very thin 200Å-thick film exhibits the large (Mr/Ms) and the in-plane magnetization. This may imply that the critical thickness based on the stripe domain theory is larger than 200Å. In order to investigate the perpendicular magnetic anisotropy in this very thin film, the triple- and multiple-layered films composed of 200-Å-thick Co-Cr layers and non-magnetic carbon spacing layers between them have been prepared. When the thickness of spacing, layers are sufficiently large, the magnetization characteristics of these films are similar to that of 200-Å-thick single layer one. On the other hand, when the spacing layer is as thin as 50Å, the magnetization in the films is perpendicular to the film plane. It has been clarified from the theoretical consideration that the magnetostatic energy of the multilayered films is lower than that of single layer ones. As a result, even the very thin films such as 200-Å-thick prepared by FTS system seems to have the large perpendicular magnetic anisotropy when the c-axis in them are well oriented.