Comment on "Standing spin waves in ferromagnetic thin films"

Hartwell recently discussed ferromagnetic film spin wave pinning referenced to a surface anomaly model. This model does predict the proper spectrum in some cases, particularly those where the substrate is scratched deliberately or the films are oxidized. For some films it is believed that a better model involves a gradient in the saturation magnetization caused by a compositional change of the alloy through the film thickness, previously described by Penn and West.