Topological transformation of synthetic ferromagnetic skyrmions: thermal assisted switching of helicity by spin-orbit torque

Kai Wu; Yuelei Zhao; Hongyuan Hao; Sheng Yang; Shuang Li; Qingfang Liu; Senfu Zhang; Xixiang Zhang; Johan Åkerman; Li Xi; Ying Zhang; Kaiming Cai; Yan Zhou

doi:10.1038/s41467-024-54851-5

Topological transformation of synthetic ferromagnetic skyrmions: thermal assisted switching of helicity by spin-orbit torque

Nat Commun. 2024 Dec 2;15(1):10463. doi: 10.1038/s41467-024-54851-5.

Authors

Kai Wu^#¹, Yuelei Zhao^#¹, Hongyuan Hao^#², Sheng Yang¹, Shuang Li¹, Qingfang Liu², Senfu Zhang^{3

4}, Xixiang Zhang⁵, Johan Åkerman^{6

7

8}, Li Xi², Ying Zhang⁹, Kaiming Cai¹⁰, Yan Zhou¹¹

Affiliations

¹ School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China.
² School of Physical Science and Technology, Lanzhou University, Lanzhou, China.
³ School of Physical Science and Technology, Lanzhou University, Lanzhou, China. zhangsenfu@lzu.edu.cn.
⁴ Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia. zhangsenfu@lzu.edu.cn.
⁵ Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
⁶ Department of Physics, University of Gothenburg, Gothenburg, Sweden.
⁷ Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Japan.
⁸ Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Japan.
⁹ State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
¹⁰ School of Physics, Huazhong University of Science and Technology, Wuhan, China.
¹¹ School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China. zhouyan@cuhk.edu.cn.

^# Contributed equally.

Abstract

This study demonstrates the controllable switching of skyrmion helicity using spin-orbit torque, enhanced by thermal effects. Electric current pulses applied to a [Pt/Co]₃/Ru/[Co/Pt]₃ multilayer stripe drive skyrmions in a direction opposite to the current flow. Continuous pulsing results in an unexpected reversal of skyrmion motion. Micromagnetic simulations reveal that skyrmions in the upper and lower ferromagnetic layers exhibit distinct helicities, forming a hybrid synthetic skyrmion. The helicity switch of this hybrid structure accounts for the motion reversal. This study introduces innovative helicity control methods, advancing spintronic device applications, including data storage and quantum computing based on skyrmion helicity.