Observation of Magnetization of Obliquely Evaporated Co-CoO Magnetic Recording Tape

Electron holography is effective for the study of the micromagnetic structure of various advanced magnetic materials. Although the microstructure of obliquely evaporated Co-CoO tapes has been explicitly described so far, the investigation of magnetization in the as-recorded state is indispensable for the in-depth understanding of the magnetization transition mechanism of the tape. In this study, for the first time, a clear image is shown depicting the magnetization transition of an oblique Co-CoO tape obtained by electron holography. The image is compared with those obtained by computer simulation taking into account the recording process. It is found that although the easy axes of Co crystal particles are titled at approximately 45deg to the tape plane, the recorded magnetization shows a circular shape with its center located slightly above the center plane of the tape. Using the images of the magnetization, some possible ways to improve the recording performance of the tape are discussed