Magnon-driven skyrmion dynamics in antiferromagnets: Effect of magnon polarization

Abstract

The controllable magnetic skyrmion motion represents a highly concerned issue in preparing advanced skyrmion-based spintronic devices. Specifically, magnon-driven skyrmion motion can be easily accessible in both metallic and insulating magnets, and thus is highly preferred over electric current control further for the ultra-low energy consumption. In this work, we investigate extensively the dynamics of skyrmion motion driven by magnon in an antiferromagnet using the collective coordinate theory, focusing on the effect of magnon polarization. It is revealed that the skyrmion Hall motion driven by circularly polarized magnon becomes inevitable generally, consistent with earlier report. Furthermore, the elastic scattering theory and numerical results unveil the strong inter-dependence between the linearly polarized magnon and skyrmion motion, suggesting the complicated dependence of the skyrmion motion on the polarization nature of driving magnon. On the reversal, the scattering from the moving skyrmion may lead to decomposition of the linearly polarized magnon into two elliptically polarized magnon bands. Consequently, a net transverse force acting on skyrmion is generated owing to the broken mirror symmetry, which in turn drives a skyrmion Hall motion. The Hall motion can be completely suppressed only in some specific condition where the mirror symmetry is preserved. The present work unveils non-trivial skyrmion-magnon scattering behavior in antiferromagnets, advancing the antiferromagnetic spintronics and benefiting to high-performance devices.

Nucleation and manipulation of single skyrmions using spin-polarized currents in antiferromagnetic skyrmion-based racetrack memories

“…In the ground state, the 2D AFM layer consists of two coupled sub-lattices (A) and (B) that are completely polarized to each other. The 2D topological soliton (AFM skyrmion) can also be nucleated, moved, and converted into an AFM DW pair in AFM systems 21,23 either by STTs, SOTs, or spin waves [24][25][26] as the FM skyrmion. Furthermore, the processing speed of AFM skyrmion is much higher than that of FM skyrmion 23 .…”

Magnon-driven dynamics of frustrated skyrmion in synthetic antiferromagnets: effect of skyrmion helicity oscillation

“…Compared with electric current, magnons as the quanta of spin waves, which drive skyrmion motion without Joule heating due to the absence of physical charge transport, are particularly attractive due to their advantage of low-energy consumption [30][31][32][33][34][35][36][37][38][39][40]. As a matter of fact, the magnon driven skyrmion dynamics in ferromagnets and antiferromagnets have been explored.…”

“…For example, magnons in ferromagnets are only right-circularly polarized and deflected by the effective field from skyrmions, which in turn drives the skyrmion toward the magnon source accompanied by Hall motion through momenta exchange [34,37,41]. Moreover, circularly polarized magnons are deflected by antiferromagnetic (AFM) skyrmions in the transverse direction, which drives skyrmion Hall motion even in antiferromagnets [38,40].…”

Suppression of Skyrmion Hall Motion in Antiferromagnets Driven by Circularly Polarized Spin Waves

“…However, skyrmion Hall motion is detrimental for data propagation in future skyrmion-based devices, as discussed above. It is predicted that the linearly polarized spin wave with particular polarization directions drives the AFM skyrmion straightly along its propagation direction without any Hall motion [27], while the strict limitation of the polarization directions affects stable application. Furthermore, the skyrmion speed driven by linearly polarized spin waves is rather low compared with one driven by circularly polarized spin wave.…”