Co/Pt perpendicular antidot arrays with engineered feature size and magnetic properties fabricated on anodic aluminum oxide templates

Abstract

Antidot arrays with perpendicular anisotropy have been fabricated by depositing Co/Pt multilayers on the anodic aluminum oxide (AAO) templates prepared on Si wafers. The antidot arrays cover an area of about $10\text{ }{\text{cm}}^{2}$. The antidot size $(D)$ and edge-to-edge $(w)$ separation between two adjacent antidots are varied over a wide range from 7 to 46 nm and 14 to 53 nm, respectively. The magnetic properties and magnetization process exhibit strong dependence on the antidot size and separation. The perpendicular coercivity $({H}_{c})$ increases from 140 Oe (continuous film) with the increase in $D$ and shows a peak at about 1350 Oe for the $D$ of around 30 nm. The ${H}_{c}$ starts to decrease for the further increase in $D$ due to the deteriorated perpendicular anisotropy. The magnetization reversal of the antidot arrays with $D$ of 30 nm or less is governed by the strong domain-wall pinning and the switching field shows less sensitivity to the angular variation from the easy axis. The magnetic domain size decreases with increase in $D$. The evolutions of magnetic properties are ascribed to the pinning effects imposed by the AAO pores. The influence of antidot size on the pinning of domain wall, ${H}_{c}$ and magnetization switching characteristics are also investigated by the micromagnetic modeling.