Interplay of the half-skyrmion topology and spin-orbit torque on the growth of magnetic stripe domains*

The spin-orbit torque (SOT) generated when a charge current is passed through a heavy metal with sizeable spin-orbit coupling [1] has attracted significant research interest, given that it gives rise to the efficient movement of novel magnetic textures, such as chiral domain walls and skyrmions. Here, we discuss an experimental study of the SOT-induced motion of magnetic stripe domains in Pt/Co/Pt and Pt/Co/Ni/Pt thin-film heterostructures that possess an interfacial Dzyaloshinskii-Moriya interaction that favors the formation of chiral Neel-type domain walls [2]. In agreement with previous reports, we find that the domains exhibit a significant transverse velocity relative to driving force of the SOT. In these past works, this behavior was attributed to the Magnus force-like skyrmion Hall effect exhibited by the stripe domain topology (equivalent to that of a half-skyrmion) [3-5]. However, magnetometry and ferromagnetic resonance spectroscopy measurements suggest that the theoretically predicted transverse motion of stripe domains in our samples may be too large to be explained by the skyrmion Hall effect. Analytically modeling the steady-state dynamical reconfiguration of the half-skyrmion profile induced by SOT, we demonstrate how motion with similar directionality and symmetry as the skyrmion Hall effect can originate – further highlighting the sensitivity of SOT to the local orientation of the domain wall magnetization profile. 

[1] M.I. Dyakonov and V.I. Perel, JTEP Lett. 13, 467 (1971).

[2] A. Fert, Mat. Sci. Form. 59-60, 439 (1990)

[3] S. Zhang, X. Zhang, et al., Sci. Adv. 6, 1876 (2020).

[4] S. Yang, K.-W. Moon, et al., Adv. Quant. Tech. 4, 2000060 (2021).