Bidirectional spin-wave-driven domain wall motion in ferrimagnets

Abstract

We investigate ferrimagnetic domain wall dynamics induced by circularly\npolarized spin waves theoretically and numerically. We find that the direction\nof domain wall motion depends on both the circular polarization of spin waves\nand the sign of net spin density of ferrimagnet. Below the angular momentum\ncompensation point, left- (right-) circularly polarized spin waves push a\ndomain wall towards (away from) the spin-wave source. Above the angular\nmomentum compensation point, on the other hand, the direction of domain wall\nmotion is reversed. This bidirectional motion originates from the fact that the\nsign of spin-wave-induced magnonic torque depends on the circular polarization\nand the subsequent response of the domain wall to the magnonic torque is\ngoverned by the net spin density. Our finding provides a way to utilize a spin\nwave as a versatile driving force for bidirectional domain wall motion.\n