Magnetic skyrmions [1] are magnetic quasi-particles with interesting properties for possible future applications in efficient low-power neuromorphic computing concepts. Thermally excited skyrmions in confined geometries, as necessary for device applications, have been shown to arrange based on commensurability effects [2]. Here, we investigate the enhanced dynamics and altered equilibrium state of a system in which the intrinsic skyrmion-skyrmion and skyrmion-boundary interaction compete with spin-orbit torques (SOTs) due applied currents [3]. In particular, we employ particle-based simulations to study four skyrmions in a triangular confinement, while injecting spin-polarized currents between two corners of the structure [4]. To analyze the observed positions of the skyrmion ensemble, we coarse-grain the skyrmion states in the system. In the context of neuromorphic computing, such coarse-graining may be key to identify the most suitable positions for potential readouts as well as to understand the collective skyrmion dynamics in systems with competing interactions at different scales. <br>
**References** <br>
[1] K. Everschor-Sitte et al., Journal of Applied Physics 124, 240901 (2018)<br>
[2] C. Song et al., Adv. Funct. Mater. 31, 2010739 (2021)<br>
[3] K. Raab et al., arxiv:2204.14720 (2022)<br>
[4] T. Winkler et al., in preparation (2022)<br>


Analyzing collective thermal Skyrmion Dynamics by coarse graining

Reservoir computing (RC) has been considered as one of the key computational principles beyond von-Neumann computing. Magnetic skyrmions, topological particle-like spin textures in magnetic thin films, are particularly promising for implementing RC [1] since they respond strongly nonlinear to external stimuli and feature inherent multiscale dynamics. We propose and demonstrate experimentally a conceptually new approach to skyrmion RC that exploits the thermally activated diffusive motion of skyrmions [2]. By confining the thermal and low-energy, electrically gated skyrmion motion, together with employing spatially resolved input and readout, we find that already a single skyrmion in a confined, triangular geometry (Fig. 1) suffices to realize non-linearly separable functions, which we demonstrate for the XOR gate along with all other Boolean logic gate operations [3] (Fig. 2). Our proposed concept can be readily extended by linking multiple confined geometries and/or by including more skyrmions in the reservoir, suggesting high potential for scalable and low-energy reservoir computing.

Brownian Reservoir Computing Realized Using Geometrically Confined Skyrmions

HOD: Skyrmions: Characterization, Dynamics and Control

technical paper

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Analyzing collective thermal Skyrmion Dynamics by coarse graining

Brownian Reservoir Computing Realized Using Geometrically Confined Skyrmions

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