Identification of Néel Vector Orientation in Antiferromagnetic Domains Switched by Currents in NiO/Pt Thin Films

Abstract

Understanding the electrical manipulation of the antiferromagnetic order is a crucial aspect to enable the design of antiferromagnetic devices working at THz frequencies. Focusing on collinear insulating antiferromagnetic $\mathrm{Ni}\mathrm{O}/\mathrm{Pt}$ thin films as a materials platform, we identify the crystallographic orientation of the domains that can be switched by currents and quantify the N\'eel-vector direction changes. We demonstrate electrical switching between different T domains by current pulses, finding that the N\'eel-vector orientation in these domains is along [$\ifmmode\pm\else\textpm\fi{}5$ $\ifmmode\pm\else\textpm\fi{}5$ 19], different compared to the bulk $⟨112⟩$ directions. The final state of the in-plane component of the N\'eel vector ${\mathbf{n}}_{\mathrm{IP}}$ after switching by current pulses $\mathbf{j}$ along the $[1\phantom{\rule{0.1em}{0ex}}\ifmmode\pm\else\textpm\fi{}1\phantom{\rule{0.1em}{0ex}}0]$ directions is ${\mathbf{n}}_{\mathrm{IP}}\ensuremath{\parallel}\mathbf{j}$. By comparing the observed N\'eel-vector orientation and the strain in the thin films, assuming that this variation arises solely from magnetoelastic effects, we quantify the order of magnitude of the magnetoelastic coupling coefficient as ${b}_{0}+2{b}_{1}=3\ifmmode\times\else\texttimes\fi{}{10}^{7}\mathrm{J}/{\mathrm{m}}^{3}$. This information is key for the understanding of current-induced switching in antiferromagnets and for the design and use of such devices as active elements in spintronic devices.