Spin photo-currents in antiferromagnets with Dzyaloshinskii–Moriya interactions

We theoretically investigate spin photo-currents in two types of antiferromagnetic insulators with Dzyaloshinskii–Moriya (DM) interactions: one with staggered DM interactions and the other with uniform DM interactions. The magnon spectrum for each system thus becomes asymmetric with respect to the propagation direction of magnons, which may be utilized to enhance the nonlinear spin conductivity. Indeed, we show that the spin conductivity in each system could be up to the order of 10 nJ/(\(\textrm{cm}^2\cdot \textrm{T}^2\)) when the system is coupled to an AC magnetic field transverse to the ordered spins. Due to the special magnon dispersion, however, an extra static field is required to achieve a high conductivity in the system with staggered DM interactions. The results could be useful in opto-spintronics based on magnetic excitations.