Skyrmion Stochastic Dynamics for Novel Computing Architectures

Abstract

Dynamics of the magnetic skyrmions can be controlled and a desired location can be achieved using spin torques [1]. There were proposals for skyrmion racetrack memory and logic gate applications [2]. But the instabilities and stochastic behavior of skyrmions due to pinning [3], temperature and applied current, and skyrmion Hall angle (SkHA) [4] make the realization of these applications challenging. Using the instabilities and stochastic behavior of skyrmions, new computing architectures, e.g., neuromorphic, probabilistic and reservoir computing can be achieved [5, 6]. The major aspects of these computations are understanding synaptic response and having a constant uncorrelated signal [2]. In this study, the stochastic property in a shuffling chamber is investigated using micromagnetic simulation. Morever, temperature response to the number of skyrmions in a chamber is analyzed. At first, skyrmion dynamics is analyzed under different geometries, constant temperatures, grains and different currents to get a stochastic skyrmion motion. Then, two locations, along the path of the skyrmions were chosen for local laser spot heating, when grain, current density and geometry were kept the same. The correlation between input and output paths were analyzed using Pearson correlation coefficient (PCC). Finally, for constant temperatures, synaptic response is shown. The study will guide for the creation of a better probabilistic computing device and artificial synapse. [1] Nakatani Y., Yamada K. and Hirohata A., Scientific Reports, 11(1), pp.1-6 (2021) [2] Luo S. and You L., APL Materials, 9(5), p.050901 (2021) [3] Stosic D., Ludermir T.B. and Milošević M.V., Physical Review B, 96(21), p.214403 (2017) [4] Litzius K., Leliaert J., Bassirian P. et al., Nature Electronics, 3(1), pp.30-36 (2020) [5] K.M. Song, J.S. Jeong, B.Pan et al., Nature Electronics 3, 148 (2020) [6] J. Zázvorka, F. Jakobs, D. Heinze et al., Nature nanotechnology 14, 658 (2019)