Berlin 2018 – scientific programme
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MA: Fachverband Magnetismus
MA 24: Focus Session: Exploiting spintronics for unconventional computing (joint session MA/TT)
MA 24.5: Talk
Wednesday, March 14, 2018, 11:30–11:45, H 1012
Thermally excited skyrmion motion for probabilistic computing — •Jakub Zázvorka1, Daniel Heinze1, Kai Litzius1,2,3, Samridh Jaiswal1,4, Sascha Kromin1, Niklas Keil1, and Mathias Kläui1,4 — 1Johannes Gutenberg University Mainz, Institute of Physics, Mainz, Germany — 2Max Plank Institute for Intelligent Systems, Stuttgart, Germany — 3Graduate School of Excellence ”Materials Science in Mainz”, Mainz, Germany — 4Singulus Technologies AG, Kahl am Main, Germany
A key problem for probabilistic computing is that cascading gates propagate undesired correlations. Therefore, one needs to reshuffle the signals to keep them uncorrelated. While for many non-conventional computing approaches non-magnetic implementations are most promising, for building a ”reshuffler”, skyrmions might be ideally suited due to the low footprint and low power compared to e.g. CMOS implementations [1]. We have studied a Ta-based material where we can stabilize skyrmions and controllably nucleate and displace them by current pulses due to spin-orbit torques. We find topologically non-trivial N=1 skyrmions that move with the application of current pulses. At zero applied current, we find thermally activated skyrmion motion. We track the trajectories of skyrmions and from the dependence of their mean-square-displacement (MSD) on time, we can identify motion by diffusion and obtain the diffusion constant. There is a strong dependence of the skyrmion diffusion parameter on temperature and the skyrmion size. Finally, we patterned the reshuffler geometry and ascertain its performance. [1] D. Pinna et al., arXiv:1701.07750, 2017.