Current-induced torques in continuous antiferromagnetic textures

Abstract

We study the influence of an electric current on a continuous noncollinear antiferromagnetic texture. Despite the lack of a net magnetic moment, we find that the exchange interaction between conduction electrons and local magnetization generally results in current-induced torques that are nonzero and similar in phenomenology to spin-transfer torques in ferromagnets. We present the generalization of the nonlinear sigma model equation of motion for the Néel vector that includes these current-induced torques, and briefly discuss the resulting current-induced antiferromagnetic domain wall motion and spin-wave Doppler shift. We give an interpretation of our results using a unifying picture of current-induced torques in ferromagnets and antiferromagnets, in which they are viewed as being due to the current-induced spin polarization resulting from an effective spin-orbit coupling.