Abstract
Motivated by the recent experiment done by Yu <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> [X. Z. Yu, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et. al.</i> , Sci. Adv., 6, 25, eaaz9744 (2020)] on magnetic skyrmion creation and annihilation by electric currents in FeGe devices with a notch structure, we examine the interaction between the electric current vorticity near the notch and localized spins, and obtain three effects of the current vorticity on the localized spins. The first one is an effective Zeeman field induced by the current vorticity. This effective Zeeman field is responsible for skyrmion creation. The second effect is a vorticity-induced Dzyaloshinskii–Moriya (DM) interaction with the direction of the DM vector being parallel to the vorticity direction and is different from the vector of the intrinsic DM interaction. This vorticity-induced DM interaction makes the skyrmions distorted. The third effect is a spin current due to the gradient of the vorticity and the spin current drives the magnetic skyrmions far from the notch. Our theory opens a new path to design the magnetic textures by using structural settings.
Highlights
T HE recent experiment on magnetic skyrmion creation and annihilation by electric currents done by Yu and the co-workers [1] has attracted a special attention
We study the effects of the spatial dependence of the electric current near the notch structure and obtain that the current vortex is coupled with conduction electron spins through the spin-vorticity coupling
We show that the vorticity induces the effective Zeeman field for the localized spin through the sd exchange interaction and the spin-vorticity coupling
Summary
T HE recent experiment on magnetic skyrmion creation and annihilation by electric currents done by Yu and the co-workers [1] has attracted a special attention. Creation and annihilation of magnetic skyrmions by electric currents in a notch structure have been studied theoretically and experimentally [4]–[7]. We present a theory which explains the above-mentioned experiment on magnetic skyrmion creation and annihilation by the electric current. We consider that the electric current near the notch structure is of spatial dependence as shown in Fig. 1 (a), which leads to a nonzero vorticity Ω(r) = ∇×vdrift, where vdrift is the drift velocity of electric current. It is found that the spatial gradient of the vorticity induces a spin current, by which the skyrmions spread to entire area of the sample.
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