Hydrodynamic theory of coupled current and magnetization dynamics in spin-textured antiferromagnets
Antiferromagnets with vanishingly small (or zero) magnetization are interesting candidates for spintronics applications. In the present paper we propose two models for description of the current-induced phenomena in antiferromagnetic textures. We show that the magnetization that originates from rotation or oscillations of antiferromagnetic vector can, via $sd$-exchange coupling, polarize the current and give rise to adiabatic and nonadiabatic spin torques. Due to the Lorentz-type dynamics of antiferromagnetic moments (unlike the Galilenian-like dynamics in ferromagnets), the adiabatic spin torque affects the characteristic lengthscale of the moving texture. Nonadiabatic spin torque contributes to the energy pumping and can induce the stable motion of antiferromagnetic texture, but, in contrast to ferromagnets, has pure dynamic origin. We also consider the current-induced phenomena in artificial antiferromagnets where the current maps the staggered magnetization of the structure. In this case the effect of nonadiabatic spin torque is similar to that in ferromagnetic constituents of the structure. In particular, the current can remove degeneracy of the translational antiferromagnetic domains indistinguishable in the external magnetic field and thus can set into motion the 180$^\circ$ domain wall.