Exchange Bias in the [CoO/Co/Pd]10 Antidot Large Area Arrays

TL;DR

This study investigates exchange bias effects in patterned [CoO/Co/Pd]10 multilayer nanostructures with antidots, revealing significant exchange bias fields and edge-related soft magnetization components, relevant for magnetic device applications.

Contribution

It introduces a nanosphere lithography method to create large-area antidot arrays in [CoO/Co/Pd]10 multilayers, demonstrating how patterning influences exchange bias and magnetic properties.

Findings

Exchange bias field up to -11 kOe observed.

Antidot radius increase slightly enhances exchange bias.

Edges induce a soft, unbiased magnetization component.

Abstract

Magnetic nanostructures revealing exchange bias effect have gained a lot of interest in recent years due to their possible applications in modern devices with various functionalities. In this paper, we present our studies on patterned [CoO/Co/Pd]10 multilayer where ferromagnetic material is in a form of clusters, instead of being a continuous layer. The system was patterned using nanosphere lithography technique which resulted in creation of an assembly of well-ordered antidots or islands over a large substrate area. We found that the overall hysteresis loop of the films consists of hard and soft components. The hard component hysteresis loop exhibits a large exchange bias field up to -11 kOe. The patterning process causes a slight increase of the exchange field as the antidot radius rises. We also found that the material on edges of the structures gives rise to a soft unbiased magnetization component.