Elastic stress-induced coercive field changes in Ni-Co-P films used in a rotating disk

The loss of recorded signal due to applied elastic stress on a NiCoP thin film recording material has been investigated by a new technique in which a uniform stress is applied by bending a sample in an applied demagnetizing field, and the change in total manetization of a uniformly magnetized sample is measured. The loss in magnetization is linear with the log of the number of bending cycles, for both convex and concave bending. Five cycles of bending under a stress of about 200 MPa reduces the coercive field of these films by several percent.