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

Mahendra Dc; Roberto Grassi; Jun-Yang Chen; Mahdi Jamali; Danielle Reifsnyder Hickey; Delin Zhang; Zhengyang Zhao; Hongshi Li; P Quarterman; Yang Lv; Mo Li; Aurelien Manchon; K Andre Mkhoyan; Tony Low; Jian-Ping Wang

doi:10.1038/s41563-018-0136-z

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

Nat Mater. 2018 Sep;17(9):800-807. doi: 10.1038/s41563-018-0136-z. Epub 2018 Jul 30.

Authors

Mahendra Dc¹, Roberto Grassi², Jun-Yang Chen², Mahdi Jamali², Danielle Reifsnyder Hickey³, Delin Zhang², Zhengyang Zhao², Hongshi Li³, P Quarterman², Yang Lv², Mo Li², Aurelien Manchon^{4

5}, K Andre Mkhoyan³, Tony Low², Jian-Ping Wang^{6

7

8}

Affiliations

¹ School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA.
² Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, USA.
³ Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA.
⁴ King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division (PSE), Thuwal, Saudi Arabia.
⁵ King Abdullah University of Science and Technology (KAUST), Computer, Electrical and Mathematical Sciences and Engineering Division (CEMSE), Thuwal, Saudi Arabia.
⁶ School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA. jpwang@umn.edu.
⁷ Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, USA. jpwang@umn.edu.
⁸ Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA. jpwang@umn.edu.

PMID: 30061733
DOI: 10.1038/s41563-018-0136-z

Abstract

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 Bi_xSe_(1-x) thin films in Bi_xSe_(1-x)/Co₂₀Fe₆₀B₂₀ heterostructures by using d.c. planar Hall and spin-torque ferromagnetic resonance (ST-FMR) methods. Remarkably, the spin torque efficiency (θ_S) 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 Bi_xSe_(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 Bi_xSe_(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 θ_S, ease of growth of the films on a silicon substrate and successful growth and switching of perpendicular CoFeB multilayers on Bi_xSe_(1-x) films provide an avenue for the use of Bi_xSe_(1-x) as a spin density generator in SOT-based memory and logic devices.

Publication types

Research Support, Non-U.S. Gov't