Mathias Kläui

Novel spintronic devices can play a role in the quest for GreenIT if they are stable and can transport and manipulate spin with low power. Devices have been proposed, where switching by energy-efficient approaches is used to manipulate topological spin structures that are stable in multilayers [1] but also in 2D van der Waals systems [2]. We combine ultimate stability of topological states due to chiral interactions [3,4] with ultra-efficient manipulation using novel spin torques [3-5]. In particular orbital torques [6] increase the switching efficiency by more than a factor 10. Going towards 2D van der Waals systems, we explore bulk spin – orbit torques resulting from the particular symmetry [7]. In such 2D heterostructures of ferromagnets and antiferromagnets, also enhanced exchange bias is observed allowing one to control the switching [8]. Finally, we use skyrmion dynamics for non-conventional stochastic computing applications, where we developed skyrmion reshuffler devices [9] based on skyrmion diffusion, which also reveals the origin of skyrmion pinning [10]. Such diffusion can furthermore be used for Token-based Brownian Computing and Reservoir Computing [11].

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[2] M. Schmitt et al., Comm. Phys. Vol. 5, 254, 2022
[3] S. Woo et al., Nature Mater., vol. 15, no. 5, pp. 501–506, 2016
[4] K. Litzius et al., Nature Phys., vol. 13, no. 2, pp. 170–175, 2017
[5] K. Litzius et al., Nature Electron., vol. 3, no. 1, pp. 30–36, 2020
[6] S. Ding et al. Phys. Rev. Lett., vol. 125, 177201, 2020; Phys. Rev. Lett., vol. 128, 067201, 2022
[7] F. Martin et al., Mater. Res. Lett., vol. 11, 84, 2023; T. Saunderson et al., Phys. Rev. Res., Vol. 4, L042022, 2022
[8] A. Puthirath-Balan et al., arxiv:2303.13167
[9] J. Zázvorka et al., Nature Nanotechnol., vol. 14, no. 7, pp. 658–661, 2019; R. Gruber et al., Nature Commun. vol. 13, pp. 3144, 2022
[10] K. Raab et al., Nature Commun. vol. 13, pp. 6982, 2022
[11] T. Dohi et al., Nature Commun. vol. 14, pp. 5424, 2023