Switching of perpendicular magnetization by spin–orbit torques in the absence of external magnetic fields

• Published in: Nature nanotechnology Vol. 9; no. 7; pp. 548 - 554
• Main Authors: Yu, Guoqiang, Upadhyaya, Pramey, Fan, Yabin, Alzate, Juan G., Jiang, Wanjun, Wong, Kin L., Takei, So, Bender, Scott A., Chang, Li-Te, Jiang, Ying, Lang, Murong, Tang, Jianshi, Wang, Yong, Tserkovnyak, Yaroslav, Amiri, Pedram Khalili, Wang, Kang L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2014; Nature Publishing Group
• Subjects: 140/146; 142/126; 147/143; 639/766/119/1001; Asymmetry; Electrons; Ferromagnetism; Magnetic fields; Magnetization; Materials Science; Memory devices; Nanotechnology; Nanotechnology and Microengineering; Oxidation; Random access memory; Switching; Symmetry; Torque; Los Angeles California; United States > US; California
• ISSN: 1748-3387; 1748-3395; 1748-3395
• DOI: 10.1038/nnano.2014.94

Magnetization switching by current-induced spin–orbit torques is of great interest due to its potential applications in ultralow-power memory and logic devices. The switching of ferromagnets with perpendicular magnetization is of particular technological relevance. However, in such materials, the presence of an in-plane external magnetic field is typically required to assist spin–orbit torque-driven switching and this is an obstacle for practical applications. Here, we report the switching of out-of-plane magnetized Ta/Co 20 Fe 60 B 20 /TaO x structures by spin–orbit torques driven by in-plane currents, without the need for any external magnetic fields. This is achieved by introducing a lateral structural asymmetry into our devices, which gives rise to a new field-like spin–orbit torque when in-plane current flows in these structures. The direction of the current-induced effective field corresponding to this field-like spin–orbit torque is out-of-plane, facilitating the switching of perpendicular magnets. Spin–orbit torques in a geometrically asymmetric device made from a perpendicularly magnetized ferromagnet can switch its magnetization without the assistance of an applied magnetic field.