Tuning Perpendicular Anisotropy Gradient in Co/Pd Multilayers by Ion Irradiation

TL;DR

This paper demonstrates how Ar+ ion irradiation can be used to create and control depth-dependent perpendicular anisotropy gradients in Co/Pd multilayers, affecting their magnetic properties.

Contribution

It introduces a method to tune anisotropy gradients in multilayers using ion irradiation, offering a new tool for magnetic property engineering.

Findings

Ion irradiation weakens surface perpendicular anisotropy

Magnetization tilts towards in-plane direction due to structural damage

Method allows control over anisotropy gradient depth and density

Abstract

The tunability of Ar+ ion irradiation of Co/Pd multilayers has been employed to create depth-dependent perpendicular anisotropy gradients. By adjusting the Ar+ kinetic energy and fluence, the depth and lateral density of the local structural modification are controlled. First-order reversal curve analysis through X-ray magnetic circular dichroism and conventional magnetometry studies show that the local structural damage weakens the perpendicular anisotropy near the surface, leading to a magnetization tilting towards the in-plane direction. The ion irradiation method is complementary to, and may be used in conjunction with, other synthesis approaches to maximize the anisotropy gradient.