Field-free spin-orbit torque switching assisted by in-plane unconventional spin torque in ultrathin [Pt/Co] N

• Published in: Nature communications Vol. 14; no. 1; p. 3932
• Main Authors: Xue, Fen, Lin, Shy-Jay, Song, Mingyuan, Hwang, William, Klewe, Christoph, Lee, Chien-Min, Turgut, Emrah, Shafer, Padraic, Vailionis, Arturas, Huang, Yen-Lin, Tsai, Wilman, Bao, Xinyu, Wang, Shan X
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 04.07.2023; Nature Publishing Group UK; Nature Portfolio
• Subjects: Circular dichroism; Cobalt; Current pulses; Density; Dichroism; Electric control; electrical engineering; electronic engineering; Energy consumption; ENGINEERING; information storage; Magnetic fields; Magnetic moments; Magnetic switching; Magnetization; Multilayers; Platinum; Silicon dioxide; Silicon substrates; Spin-orbit interactions; Torque
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-39649-1

Electrical manipulation of magnetization without an external magnetic field is critical for the development of advanced non-volatile magnetic-memory technology that can achieve high memory density and low energy consumption. Several recent studies have revealed efficient out-of-plane spin-orbit torques (SOTs) in a variety of materials for field-free type-z SOT switching. Here, we report on the corresponding type-x configuration, showing significant in-plane unconventional spin polarizations from sputtered ultrathin [Pt/Co] , which are either highly textured on single crystalline MgO substrates or randomly textured on SiO coated Si substrates. The unconventional spin currents generated in the low-dimensional Co films result from the strong orbital magnetic moment, which has been observed by X-ray magnetic circular dichroism (XMCD) measurement. The x-polarized spin torque efficiency reaches up to -0.083 and favors complete field-free switching of CoFeB magnetized along the in-plane charge current direction. Micromagnetic simulations additionally demonstrate its lower switching current than type-y switching, especially in narrow current pulses. Our work provides additional pathways for electrical manipulation of spintronic devices in the pursuit of high-speed, high-density, and low-energy non-volatile memory.