Novel noncollinear antiferromagnets with spontaneous time-reversal symmetry breaking, nontrivial band topology, and unconventional transport properties have received immense research interest over the past decade due to their rich physics and enormous promise in technological applications. One of the central focuses in this emerging field is exploring the relationship between the microscopic magnetic structure and exotic material properties. Here, the nanoscale imaging of both spin-orbit-torque-induced deterministic magnetic switching and chiral spin rotation in noncollinear antiferromagnet Mn3Sn films using nitrogen-vacancy (NV) centers is reported. Direct evidence of the off-resonance dipole-dipole coupling between the spin dynamics in Mn3Sn and proximate NV centers is also demonstrated with NV relaxometry measurements. These results demonstrate the unique capabilities of NV centers in accessing the local information of the magnetic order and dynamics in these emergent quantum materials and suggest new opportunities for investigating the interplay between topology and magnetism in a broad range of topological magnets.

Carbon dioxide electrolysis powered by renewable energy is a potentially attractive approach to close the carbon cycle and produce key chemical feedstocks. Here, we demonstrate the substantial influence of tensile strain on the selectivity of CO2 reduction toward higher value-added, multicarbon products by modulating the residual mismatch strain of Cu(001) thin film catalysts grown epitaxially on single-crystal Si substrates. By decreasing film thickness from 100 to 20 nm, up to 0.22% tensile strain is introduced in-plane, shifting the measured Cu d-band center at the surface upward, in good agreement with theory. CO2 electrolysis at moderate overpotential (−0.9 V vs reversible hydrogen electrode (RHE)) in 0.1 M KHCO3 electrolyte reveals that the shift in d-band center results in the suppression of single-carbon products, while activity for multicarbon products is maintained. Examination of the ratio of partial current densities for multicarbon products relative to CO and CH4 suggests increased CO insertion and hydrogenation on the tensile-strained Cu(001) surface, driven by a change in the adsorbate bonding because of an increased interaction with the upshifted d-band. This work provides direct experimental evidence on model thin film CO2 catalysts that strain can be systematically manipulated as a valuable tool, independent of catalyst composition, for the design of efficient CO2 electrocatalysts toward energy-dense products.

The Dzyaloshinskii–Moriya interaction (DMI) in magnetic systems stabilizes spin textures with preferred chirality, applicable to next‐generation memory and computing architectures. In perpendicularly magnetized heavy‐metal/ferromagnet films, the interfacial DMI originating from structural inversion asymmetry and strong spin‐orbit coupling favors chiral Néel‐type domain walls (DWs) whose energetics and mobility remain at issue. Here, a new effect is characterized in which domains expand unidirectionally in response to a combination of out‐of‐plane and in‐plane magnetic fields, with the growth direction controlled by the in‐plane field strength. These growth directionalities and symmetries with applied fields cannot be understood from static treatments alone. The authors theoretically demonstrate that perpendicular field torques stabilize steady‐state magnetization profiles highly asymmetric in elastic energy, resulting in a dynamic symmetry breaking consistent with the experimental findings. This phenomenon sheds light on the mechanisms governing the dynamics of Néel‐type DWs and expands the utility of field‐driven DW motion to probe and control chiral DWs.

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