Abstract
The discovery of magnetism in two-dimensional (2D) van der Waals (vdW) materials1–4 has flourished a new endeavour of fundamental problems in magnetism as well as potential applications in computing, sensing and storage technologies5–10. Of particular interest are antiferromagnets 11, 12, which due to their intrinsic antiferromagnetic exchange coupling show several advantages in relation to ferromagnets such as robustness against external magnetic perturbations. This property is one of the cornerstones of antiferromagnets13 and implies that in formation stored in antiferromagnetic domains is invisible to applied magnetic fields preventing it from being erased or manipulated. Here we show that, despite this fundamental understanding, the magnetic domains of recently discovered 2D vdW MnPS3 antiferromagnet14, 15 can be controlled via external magnetic fields and electric currents. We realize ultrafast domain-wall dynamics with velocities up to ∼1500 m s−1 and ∼3000 m s−1 respectively to a broad range of field magnitudes (0.0001−22 T) and current densities (108 − 1010 A cm−2). Both domain wall dynamics are determined by the edge terminations which generated uncompensated spins following the underlying symmetry of the honeycomb structure. We find that edge atoms belonging to different magnetic sublattices function as geometrical constrictions preventing the displacement of the wall, whereas having atoms of the same sublattice at both edges of the material allows for the field-driven domain wall motion which is only limited by the spin-flop transition of the antiferromagnet beyond 25 T. Conversely, electric currents can induce motion of domain walls in most of the edges except those where the two sublattices are present at the borders (e.g. armchair edges). Furthermore, the orientation of the layer relative to the current flow provides an additional degree of freedom for controlling and manipulating magnetic domains in MnPS3. Our results indicate that the implementation of 2D vdW antiferromagnets in real applications requires the engineering of the layer edges which enables an unprecedented functional feature in ultrathin device platforms.
Domain wall dynamics in two-dimensional van der Waals ferromagnets
