UC Davis

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 shows 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. © 2014 AIP Publishing LLC.