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)/Co20Fe60B20 heterostructures 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.
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We thank P. Crowell for proofreading the manuscript and M. Kawaguchi for helpful discussions on data analysis. We also thank T. Peterson and G. Stecklein for their help with the PPMS measurements. This work was supported by C-SPIN, one of six STARnet programme research centres. This work utilized (1) the College of Science and Engineering (CSE) Characterization Facility, University of Minnesota (UM), supported in part by the NSF through the UMN MRSEC programme (no. DMR-1420013), and (2) the CSE Minnesota Nano Center, UM, supported in part by the NSF through the NNIN programme. A.M. was supported by the King Abdullah University of Science and Technology (KAUST).
The authors declare no competing interests.
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DC, M., Grassi, R., Chen, J. et al. Room-temperature high spin–orbit torque due to quantum confinement in sputtered BixSe(1–x) films. Nature Mater 17, 800–807 (2018). https://doi.org/10.1038/s41563-018-0136-z
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