Staggering antiferromagnetic domain wall velocity in a staggered spin-orbit field

Abstract

We demonstrate the possibility to drive an antiferromagnet domain-wall at high velocities by field-like N\'{e}el spin-orbit torques. Such torques arise from current-induced local fields that alternate their orientation on each sub-lattice of the antiferromagnet and whose orientation depend primarily on the current direction, giving them their field-like character. The domain-wall velocities that can be achieved by this mechanism are two orders of magnitude greater than the ones in ferromagnets. This arises from the efficiency of the staggered spin-orbit fields to couple to the order parameter and from the exchange-enhanced phenomena in antiferromagnetic texture dynamics, which leads to a low domain-wall effective mass and the absence of a Walker break-down limit. In addition, because of its nature, the staggered spin-orbit field can lift the degeneracy between two 180$^\circ$ rotated states in a collinear antiferromagnet and provides a force that can move such walls and control the switching of the states.