Vertically Graded Anisotropy in Co/Pd Multilayers

TL;DR

This study demonstrates that depth-dependent magnetic anisotropy in Co/Pd multilayers, achieved through thickness grading, effectively reduces the magnetic field needed for data writing by promoting domain nucleation.

Contribution

It provides experimental evidence that depth grading of anisotropy in multilayers can lower write-field requirements, confirming theoretical predictions.

Findings

Anisotropy gradient observed via polarized neutron reflectometry.

Gradient promotes domain nucleation during magnetization reversal.

Depth grading reduces the magnetic field needed for writing.

Abstract

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.