Skyrmions in chiral magnetic multilayers

Christopher Marrows, University of Leeds

Magnetic skyrmions are topologically-nontrivial spin textures with particle-like properties [1]. Their size, topological stability, and mobility suggest their use in future generations of spintronic devices, the prototype of which is the skyrmion racetrack [2]. To realise a racetrack requires three basic operations: the nucleation (writing), propagation (manipulation), and detection (reading) of a skyrmion, all by electrical means. Here we show that all three are experimental feasible at room temperature in Pt/Co/Ir or Pt/CoB/Ir multilayers in which the different heavy metals above and below the magnetic layer break inversion symmetry and induce chirality by means of the Dzyaloshinskii-Moriya interaction, defining the structure of Néel skyrmion spin textures [3]. We show deterministic nucleation on nanosecond timescales using an electrical point contact on top of the multilayer [4] (Figure 1), current-driven propagation along a wire in which the skyrmions are channelled by defects in the multilayer [5], and their detection by means of the Hall effect (Figure 2) that reveals an unexpectedly large contribution to the Hall signal that correlates with the topological winding number [6].

[1] N. Nagaosa & Y. Tokura, Nat. Nanotech. 8, 899 (2013)
[2] A. Fert et al. Nature Nanotech. 8, 152 (2013)
[3] K. Zeissler et al. Sci. Rep. 7, 15125 (2017)
[4] S. Finizio et al., Nano Lett. 19, 7246 (2019)
[5] K. Zeissler et al., Nature Comm. 11, 428 (2020)
[6] K. Zeissler et al. Nature Nanotech. 13, 1161 (2018)

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