Bidirectional spin-wave-driven domain wall motion in ferrimagnets

Abstract

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

The dynamics of a domain wall in ferrimagnets driven by spin-transfer torque

“…1 for the schematic illustration. We would like to remark here that the analogous result of the reversal of the domain-wall motion has been reported in the theoretical study of the spin-wave-driven ferrimagnetic domain-wall motion [43].…”

“…To confirm the obtained analytical results, we perform numerical simulations by solving the following coupled atomistic LLG equations for RE-TM ferrimagnets [16,43,45]:…”

Dynamics of high-velocity domain wall motion and spin wave excitation in trilayer structures

“…As the wire width and thickness increases, the normally symmetric transverse wall first transitions into an asymmetric transverse structure and then into a vortex, 5 where the magnetization circulates around the center of the wall, followed by more complex wall structures at very large dimensions. 4,6 Domain walls may be propagated along a wire using a magnetic field, 7,8 or alternatively applied currents, 9,10 spin waves 11,12 or stress gradients. 13,14 At low fields, walls maintain their structure and move with a velocity v that increases linearly with field H, consistent with onedimensional approximations 15…”

Driving a magnetized domain wall in an antiferromagnet by magnons

“…11,12 Also, a current of magnons, quanta of spin waves, has been shown to be able to induce the dynamics of an antiferromagnetic domain wall by exerting a magnonic force and a magnonic torque. [13][14][15][16] The previous researches on the interaction between magnons and antiferromagnetic domain walls have, however, been focused on the situations in which an external magnetic field is absent. 13,14,16 In this paper, we study the interaction of magnons and an antiferromagnetic domain wall in the presence of an external magnetic field, focusing on the effect of the field-induced magnetization of a domain wall on its scattering with magnons.…”

“…[13][14][15][16] The previous researches on the interaction between magnons and antiferromagnetic domain walls have, however, been focused on the situations in which an external magnetic field is absent. 13,14,16 In this paper, we study the interaction of magnons and an antiferromagnetic domain wall in the presence of an external magnetic field, focusing on the effect of the field-induced magnetization of a domain wall on its scattering with magnons. We obtain the exact solutions for a magnetized domain wall and spin waves on top of it within the "relativistic" field theory of the non-linear sigma model for antiferromagnets [17][18][19] by adopting the previous results for a nonmagnetized domain wall developed in Ref.…”