Thin soft sendust laminated CoPt hard films

The C-axis of the Co-based permanent magnet films tends to grow gradually toward perpendicular direction as the film thickness increases. Reported here is a novel way to solve this problem. That is to laminate the Co-based hard magnet films with thin soft magnetic films. The effects of soft film underlayer and lamination, on the magnetic properties of CoPt films has been studied and reported here. Three types of soft magnetic material NiFe, NiFeRe and FeAlSi were chosen to conduct the experiments. Amorphous thin soft sendust film was found to meet the goal. It is found that there was a dramatic improvement of the in-plane loop squareness by inserting a 100 Å amorphous FeAlSi film into the 1200 Å CoPt film. The squareness (S) and the remnant magnetization thickness product (MrT) of the CoPt film (1200 Å) without soft FeAlSi film lamination are 0.27 and 3.0 memu/cm², respectively, while the S and the MrT of the CoPt film (1200 Å) with soft FeAlSi lamination are 0.60 and 6.32 memu/cm², respectively. Multi-lamination is possible if thick CoPt film is required in applications