Circular motion of non-collinear spin textures in Corbino disks: Dynamics of Néel- versus Bloch-type skyrmions and skyrmioniums
arxiv(2024)
摘要
Magnetic skyrmions are nano-scale magnetic whirls that can be driven by
currents via spin torques. They are promising candidates for spintronic devices
such as the racetrack memory, where a motion along the uniform current is
typically desired. However, in Corbino disks, the goal is to achieve a circular
motion, perpendicular to the radially applied current. As we show, based on
analytical calculations and micromagnetic simulations, Bloch skyrmions engage
in a circular motion with frequencies in the MHz range when driven by
spin-orbit torques. In contrast, Néel skyrmions get stuck at the edges of the
disk. Our analysis reveals that the antagonistic dynamics between Bloch- and
Néel-type magnetic textures arise from their helicity. Furthermore, we find
that skyrmioniums, which are topologically trivial variations of skyrmions,
move even faster and allow an increase in the current density without being
pushed toward the edges of the disk. When driven by spin-transfer torques
instead, Bloch and Néel skyrmions no longer exhibit different dynamics.
Instead, they move along a circular trajectory due to the skyrmion Hall effect
caused by their topological charge. Consequently, the topologically trivial
skyrmioniums inevitably become trapped at the disk edge in this scenario. To
provide a comprehensive understanding, our study also examines currents applied
tangentially, further enriching our insights into skyrmion dynamics and
appropriate current injection methods for skyrmion-based devices.
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