Skyrmion 101 in Thin Films and Multilayers

Stefan Blügel, Forschungszentrum Jülich

June 19, 2020

Spin-orbit interaction in combination with structural inversion asymmetry on magnetic surfaces, interfaces, heterostructures and nanostructures is a source of a variety of spin-dependent transport phenomena and novel magnetic textures, the chiral magnetic skyrmions [1] being the best known. In this presentation I display our effort to optimize magnetic nanostructures for skyrmions [2-7] in a potential race-track memory application. I discuss the issues of skyrmion size, life time [8] and detection [9, 10]. If time permits, I also discuss further localized particles such as bobbers [11] and antiskyrmions [12] for alternatives in race-track applications.

Our investigations make use of a multiscale approach based on (i) density-functional theory (FLAPW method as implemented in the FLEUR code [13] and the Korringa-Kohn-Rostoker method as implemented in juKKR [14]) combined with (ii) atomistic spindynamics code SPIRIT [15] by which the lifetime of the skyrmions are determined combining the Geodesic Nudged Elastic Band method (GNEB) [16] or the Systematic Saddle Point Search method [17] with the harmonic transition state theory, and (iii) micromagnetic reasoning.

We acknowledge funding by EU-H2020 project MAGicSky (No 665095), DARPA TEE program (#HR0011831554) from DOI, as well as computing time from JARA-HPC and Jülich Supercomputing Centre.

[1] Stefan Heinze et al., Nat. Phys. 7, 713 (2011).
[2] Ashis Kumar Nandy
et al., PRL 116, 177202 (2016).
[3] Abdu Belabbes
et al., 117, 247202 (2016).
[4] Bertrand. Dupé
et al., Nat. Commun. 7, 11779 (2016).
[5] Hongying Jia
et al., Phys. Rev. B 98, 144427 (2018).
[6] Hongying Jia
et al., Phys. Rev. M 4, 024405 (2020).
[7] Bernd Zimmermann
et al., Appl. Phys. Lett. 113, 232403 (2018).
[8] Gideon P. Müller
et al., Phys. Rev. Lett. 121, 197202 (2018).
[9] Dax M. Crum
et al., Nat. Comm. 6, 8541 (2015).
[10] Manuel dos Santos Dias
et al., Nat. Comm. 7, 13613 (2016).
[11] Fengshan Zheng
et al., Nat. Nanotech. 13, 451 (2018).
[12] Markus Hoffmann
et al., Nat.Comm. 8, 00308 (2017).
[13] For a program description, see www.flapw.de.
[14] For a program description, see https://jukkr.fz-juelich.de.
[15] For a program description, see https://spirit-code.github.io.
[16] Pavel F. Bessarab et al., Sci. Rep. 8, 3433 (2018).
[17] Gideon P. Müller
et al., Phys. Rev. Lett. 121, 197202 (2018).