Chirality-Induced Noncollinear Magnetization and Asymmetric Domain-Wall Propagation in Hydrogenated CoPd Thin Films

Abstract

Array-patterned CoPd-based heterostructures are created through e-beam lithography and plasma pretreatment that induces oxidation with depth gradient in the CoPd alloy films, breaking the central symmetry of the structure. Effects on the magnetic properties of the follow-up hydrogenation of the thin film are observed via magneto-optic Kerr effect microscopy. The system exhibits a strong vertical and lateral antiferromagnetic coupling in the perpendicular component between the areas with and without plasma pretreatment, and asymmetric domain-wall propagation in the plasma-pretreated areas during magnetization reversal. These phenomena exhibit evident magnetic chirality and can be interpreted with the Ruderman–Kittel–Kasuya–Yosida coupling and the Dzyaloshinskii–Moriya interaction (DMI). The sample processing demonstrated in this study allows easy incorporation of lithography techniques that can define areas with or without DMI to create intricate magnetic patterns on the sample, which provides an avenue toward more sophisticated control of canted spin textures in future spintronic devices.

Magnetic patterning of Co/Ni layered systems by plasma oxidation

“…Considering that PO is an easy to use, low cost, and commonly used technique in industrial applications, it may constitute an improvement over other magnetic patterning methods. It should be emphasized, that PO is performed not only for magnetic tailoring 60 , but it is also widely used to fabricate different non-magnetic structures for example cutting of a single-walled carbon nanotubes to produces carboxylic acid terminated electrodes with separation smaller than 10 nm 61 or realizing self-aligned gold disks in graphene antidots in which the gap between edges of the gold disks and graphene antidots is ~ 100 nm 62 . All these results show that it is possible to control PO process with high precision using different lithographic masks.…”