Controlling magnetization reversal in Co/Pt nanostructures with perpendicular anisotropy

TL;DR

This study presents a straightforward approach to control magnetization reversal in Co/Pt nanostructures by using nanoporous alumina templates with varying aspect ratios, affecting domain-wall pinning and rotation mechanisms.

Contribution

It introduces a method to tailor magnetization reversal modes in Co/Pt multilayers through substrate topography manipulation using AAO templates.

Findings

Large aspect ratio AAO induces domain-wall pinning.

Smaller aspect ratio favors rotation-dominated reversal.

Reversal mode change is due to topographical effects.

Abstract

We demonstrate a simple method to tailor the magnetization reversal mechanisms of Co/Pt multilayers by depositing them onto large area nanoporous anodized alumina (AAO) with various aspect ratios, A = pore depth/diameter. Magnetization reversal of composite (Co/Pt)/AAO films with large A is governed by strong domain-wall pinning which gradually transforms into a rotation-dominated reversal for samples with smaller A, as investigated by a first-order reversal curve method in conjunction with analysis of the angular dependent switching fields. The change of the magnetization reversal mode is attributed to topographical changes induced by the aspect ratio of the AAO templates.