Antiferromagnetic half-skyrmions electrically generated and controlled at room temperature

Abstract

Topologically protected magnetic textures are promising candidates for information carriers in future memory devices, as they can be efficiently propelled at very high velocities using current-induced spin torques. These textures-nanoscale whirls in the magnetic order-include skyrmions, half-skyrmions (merons) and their antiparticles. Antiferromagnets have been shown to host versions of these textures that have high potential for terahertz dynamics, deflection-free motion and improved size scaling due to the absence of stray field. Here we show that topological spin textures, merons and antimerons, can be generated at room temperature and reversibly moved using electrical pulses in thin-film CuMnAs, a semimetallic antiferromagnet that is a testbed system for spintronic applications. The merons and antimerons are localized on 180° domain walls, and move in the direction of the current pulses. The electrical generation and manipulation of antiferromagnetic merons is a crucial step towards realizing the full potential of antiferromagnetic thin films as active components in high-density, high-speed magnetic memory devices.

Fig. 1. AF textures in CuMnAs.

a, Spin structure and force acting on an AF Bloch-type meron under an applied current pulse J. b, Unit cell and magnetic structure of CuMnAs. c,d, XMLD–PEEM images of a vortex structure in CuMnAs. The blue single- and double-headed arrows indicate the X-ray incidence and polarization vectors, while the colour wheels and red double-headed arrows indicate the spin axis orientation inferred from the XMLD contrast. The scale bar corresponds to 1 μm. e, Optical image of the device structure used for electrical pulsing. The spatial scale bar corresponds to 10 μm.

Fig. 2. Generation of AF meron–antimeron pairs using an electrical pulse.

a, XMLD–PEEM image of a 180° AFDW located in the top arm of the device. White and black contrast corresponds to Néel vector orientation perpendicular and parallel to the X-ray linear polarization (blue double-headed arrow in top right of b), respectively. The spin axis variation across the AFDW width is depicted by red arrows. The spatial scale bar corresponds to 600 nm. b, The AFDW after applying a 1 ms electrical pulse with 21 V (1.2 × 10⁷ A cm⁻²) amplitude along the [0$\overline{1}$0] CuMnAs crystal direction (yellow arrow), showing sections of reversed chirality. The chirality changes are associated with AF vortices and antivortices. c,d, Simulated XMLD–PEEM image and Néel vector heatmaps for an AFDW showing chirality reversal. The colour bar represents the magnitude of the Néel vector along each component (L_x,y,z). e,f, Characteristic Bloch-type meron (e) and antimeron (f) with out-of-plane core spin component, located at positions highlighted by red and white filled circles in c. Source data

Fig. 3. Movement of meron–antimeron pairs using electrical pulses.

a–h, XMLD–PEEM images of the 180° AFDW after applying successive 1 ms, 21 V electrical pulses in the directions indicated by the yellow arrows. The width of each image corresponds to 1.2 μm. i, The average displacement of vortices 1 to 3 indicated in a, measured after each pulse. Source data

Fig. 4. Isolated meron–antimeron pairs localized at the points of chirality reversal on 180° AFDW loops.

a,d, XMLD–PEEM images of a single 180° AFDW loop (a) and double 180° AFDW loops (d). Spatial scale bars correspond to 350 nm. b,c,e,f, Simulated XMLD–PEEM images (b,e) and Néel vector heatmaps (c,f) for both structures showing meron–antimeron pairs situated at points of AFDW chirality reversal. The colour bar represents the magnitude of the Néel vector along each component (L_x,y,z).