2018

Room-temperature high spin–orbit torque due to quantum confinement in sputtered Bi x Se (1–x) films

Room-temperature high spin–orbit torque due to quantum confinement in sputtered Bi x Se (1–x) films
D.C. Mahendra, R. Grassi, J.-Y. Chen, M. Jamali, D. Reifsnyder Hickey, D. Zhang, Z. Zhao, H. Li, P. Quarterman, Y. Lv, M. Li, A. Manchon, K.A. Mkhoyan, T. Low, J.-P. Wang
Nat. Mater. 17, 800-807 (2018)
D.C. Mahendra, R. Grassi, J.-Y. Chen, M. Jamali, D. Reifsnyder Hickey, D. Zhang, Z. Zhao, H. Li, P. Quarterman, Y. Lv, M. Li, A. Manchon, K.A. Mkhoyan, T. Low, J.-P. Wang
.
2018
The spin–orbit torque (SOT) that arises from materials with large spin–orbit coupling promises a path for ultralow power and fast magnetic-based storage and computational devices. We investigated the SOT from magnetron-sputtered BixSe(1–x) thin films in BixSe(1–x)/Co20Fe60B20heterostructures by using d.c. planar Hall and spin-torque ferromagnetic resonance (ST-FMR) methods. Remarkably, the spin torque efficiency (θS) was determined to be as large as 18.62 ± 0.13 and 8.67 ± 1.08 using the d.c. planar Hall and ST-FMR methods, respectively. Moreover, switching of the perpendicular CoFeB multilayers using the SOT from the BixSe(1–x) was observed at room temperature with a low critical magnetization switching current density of 4.3 × 105 A cm–2. Quantum transport simulations using a realistic sp3 tight-binding model suggests that the high SOT in sputtered BixSe(1–x) is due to the quantum confinement effect with a charge-to-spin conversion efficiency that enhances with reduced size and dimensionality. The demonstrated θS, ease of growth of the films on a silicon substrate and successful growth and switching of perpendicular CoFeB multilayers on BixSe(1–x) films provide an avenue for the use of BixSe(1–x) as a spin density generator in SOT-based memory and logic devices.​​