Intrinsic defects in perpendicularly magnetized multilayer thin films and nanostructures

Intrinsic magnetic defects in perpendicularly magnetized nanostructures reduce the predictability of device and developing recording technologies. In addition to a distribution of local anisotropy fields, we show that such defects also exhibit variations in local anisotropy axes. The magnetic defects are identified by the application of in-plane and out-of-plane magnetic fields and magnetic force microscopy imaging. Those defects that control magnetization reversal in arrays of patterned Co/Pd multilayers are highly dependent on applied field orientation. The symmetry of the defects with respect to the applied field direction indicates that the anisotropy consists of a canted axis, deviating from the surface normal. Micromagnetic simulations confirm that variations in anisotropy axis can cause a significant change in reversal field depending on the location and orientation of the defects, consistent with experimental results.