ScholarBank@NUShttps://scholarbank.nus.edu.sgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Wed, 31 May 2023 16:27:09 GMT2023-05-31T16:27:09Z5021- Room temperature magnetization switching in topological insulator-ferromagnet heterostructures by spin-orbit torqueshttps://scholarbank.nus.edu.sg/handle/10635/174390Title: Room temperature magnetization switching in topological insulator-ferromagnet heterostructures by spin-orbit torques
Authors: Wang, Y; Zhu, D; Wu, Y; Yang, Y; Yu, J; Ramaswamy, R; Mishra, R; Shi, S; Elyasi, M; Teo, K.-L; Wu, Y; Yang, H
Abstract: Topological insulators with spin-momentum-locked topological surface states are expected to exhibit a giant spin-orbit torque in the topological insulator/ferromagnet systems. To date, the topological insulator spin-orbit torque-driven magnetization switching is solely reported in a Cr-doped topological insulator at 1.9 K. Here we directly show giant spin-orbit torque-driven magnetization switching in a Bi2Se3/NiFe heterostructure at room temperature captured using a magneto-optic Kerr effect microscope. We identify a large charge-to-spin conversion efficiency of ~1-1.75 in the thin Bi2Se3 films, where the topological surface states are dominant. In addition, we find the current density required for the magnetization switching is extremely low, ~6 × 105 A cm-2, which is one to two orders of magnitude smaller than that with heavy metals. Our demonstration of room temperature magnetization switching of a conventional 3d ferromagnet using Bi2Se3 may lead to potential innovations in topological insulator-based spintronic applications. © 2017 The Author(s).
Sun, 01 Jan 2017 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/1743902017-01-01T00:00:00Z
- Effect of surface state hybridization on current-induced spin-orbit torque in thin topological insulator filmshttps://scholarbank.nus.edu.sg/handle/10635/178616Title: Effect of surface state hybridization on current-induced spin-orbit torque in thin topological insulator films
Authors: Ho, C.S; Wang, Y; Siu, Z.B; Tan, S.G; Jalil, M.B.A; Yang, H
Abstract: We investigate the thickness optimization for maximum current-induced spin-orbit torque (SOT) generated by topological surface states (TSS's) in a bilayer system comprising of a ferromagnetic layer coupled to a thin topological insulator (TI) film. We show that by reducing the TI thickness, two competing effects on the SOT are induced: (i) the torque strength is stronger as the bulk contribution is decreased; (ii) on the other hand, the torque strength becomes suppressed due to increasing hybridization of the surface states. The latter is attributed to the opposite helicities of the coupled TSS's. We theoretically model the interplay of these two effects and derive the optimal TI thickness to maximize the spin torque, which is estimated to be about 3-5 nm for typical Bi2Se3 films. © 2017 The Author(s).
Sun, 01 Jan 2017 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/1786162017-01-01T00:00:00Z