Identifiying the domain wall spin structure in current-induced switching of antiferromagnetic NiO/Pt

TL;DR

This paper investigates the structure of antiferromagnetic domain walls in NiO/Pt bilayers, revealing how current pulses generate and characterize confined T-domain walls with specific spin orientations, advancing spintronic device understanding.

Contribution

It demonstrates current-induced switching creates T-domains with unique domain wall spin structures in NiO/Pt, modeled by strain effects, and measures the domain wall width.

Findings

Circular domains generated by current pulses in NiO/Pt.

Domain wall spins point toward the average of the two T-domains.

Domain wall width measured at approximately 98 nm.

Abstract

The understanding of antiferromagnetic domain walls, which are the interface between domains with different N\'eel order orientations, is a crucial aspect to enable the use of antiferromagnetic materials as active elements in future spintronic devices. In this work, we demonstrate that in antiferromagnetic NiO/Pt bilayers circular domain structures can be generated by switching driven by electrical current pulses. The generated domains are T-domains, separated from each other by a domain wall whose spins are pointing toward the average direction of the two T-domains rather than the common axis of the two planes. Interestingly, this direction is the same for the whole circular domain indicating the absence of strong Lifshitz invariants. The domain wall can be micromagnetically modeled by strain distributions in the NiO thin film induced by the MgO substrate, deviating from the bulk anisotropy. From our measurements we determine the domain wall width to have a full width at half maximum of $\Delta = 98 \pm 10$ nm, demonstrating strong confinement.