Vertically Graded Anisotropy in Co/Pd Multilayers

Depth-grading of magnetic anisotropy in perpendicular magnetic media has been predicted to reduce the field required to write data without sacrificing thermal stability. To study this prediction, we have produced Co/Pd multilayers with depth-dependent Co layer thickness. Polarized neutron reflectometry shows that the thickness grading results in a corresponding magnetic anisotropy gradient. Magnetometry reveals that the anisotropy gradient promotes domain nucleation upon magnetization reversal - a clear experimental demonstration of the effectiveness of graded anisotropy for reducing write-field.