The 20-nm Skyrmion Generated at Room Temperature by Spin-Orbit Torques
Jiahao Liu1,2,3†, Zidong Wang1,2†, Teng Xu1,2, Hengan Zhou1,2, Le Zhao1,2, Soong-Guen Je4,5, Mi-Young Im4, Liang Fang3, and Wanjun Jiang1,2*
1State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China 2Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China 3Institute for Quantum Information & State Key Laboratory of High Performance Computing, College of Computer, National University of Defense Technology, Changsha 410073, China 4Center for X-ray Optics, Lawrence Berkeley National Laboratory, Cyclotron Road, Berkeley, CA 94720, USA 5Department of Physics, Chonnam National University, Gwangju, 61186, Republic of Korea
Abstract：The discovery of magnetic skyrmions provides a promising pathway for developing functional spintronic memory and logic devices. Towards the future high-density memory application, nanoscale skyrmions with miniaturized diameters, ideally down to 20 nm are required. Using x-ray magnetic circular dichroism transmission microscopy, nanoscale skyrmions are observed in the [Pt/Co/Ir]$_{15}$ multilayer at room temperature. In particular, small skyrmions with minimum diameters approaching 20 nm could be generated by the current-induced spin-orbit torques. Through implementing material specific parameters, the dynamic process of skyrmion generation is further investigated by performing micromagnetic simulations. According to the simulation results, we find that both the tube-like Néel-type skyrmions and the bobber-like Néel-type skyrmions can be electrically generated. In particular, the size of the bobber-like Néel-type skyrmions can be effectively reduced by the spin-orbit torques, which leads to the formation of 20 nm Néel-type skyrmions. Our findings could be important for understanding the formation dynamics of nanoscale Néel-type spin textures, skyrmions and bobber in particular, which could also be useful for promoting nanoscale skyrmionic memories and logic devices.
2022, Vol. 39 
