Switching Of A Magnet By Spin-Orbit Torque From A Topological Dirac Semimetal

Recent experiments show that topological surface states (TSS) in topological insulators (TI) can be exploited to manipulate magnetic ordering in ferromagnets. In principle, TSS should also exist for other topological materials, but it remains unexplored as to whether such states can also be utilized to manipulate ferromagnets. Herein, current-induced magnetization switching enabled by TSS in a non-TI topological material, namely, a topological Dirac semimetal alpha-Sn, is reported. The experiments use an alpha-Sn/Ag/CoFeB trilayer structure. The magnetization in the CoFeB layer can be switched by a charge current at room temperature, without an external magnetic field. The data show that the switching is driven by the TSS of the alpha-Sn layer, rather than spin-orbit coupling in the bulk of the alpha-Sn layer or current-produced heating. The switching efficiency is as high as in TI systems. This shows that the topological Dirac semimetal alpha-Sn is as promising as TI materials in terms of spintronic applications.