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Title: Large spin-orbit torques in Pt/Co-Ni/W heterostructures

Abstract

The spin orbit torques (SOTs) in perpendicularly magnetized Co-Ni multilayers sandwiched between two heavy metals (HM) have been studied. By exploring various HM materials, we show an efficient enhancement or cancellation of the total SOT, depending on the combination of the two HM materials. The maximum SOT effective field is obtained in Pt/Co-Ni/W heterostructures. We also model our double HM system and show that the effective spin Hall angle has a peak value at certain HM thicknesses. Measuring the SOT in Pt/Co-Ni/W for various W thicknesses confirms an effective spin Hall angle up to 0.45 in our double HM system.

Authors:
; ; ;  [1]
  1. Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)
Publication Date:
OSTI Identifier:
22594441
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 4; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COBALT; HEAVY METALS; LAYERS; NICKEL; ORBITS; PEAKS; PLATINUM; SPIN; THICKNESS; TORQUE

Citation Formats

Yu, Jiawei, Qiu, Xuepeng, Legrand, William, and Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg. Large spin-orbit torques in Pt/Co-Ni/W heterostructures. United States: N. p., 2016. Web. doi:10.1063/1.4959958.
Yu, Jiawei, Qiu, Xuepeng, Legrand, William, & Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg. Large spin-orbit torques in Pt/Co-Ni/W heterostructures. United States. doi:10.1063/1.4959958.
Yu, Jiawei, Qiu, Xuepeng, Legrand, William, and Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg. 2016. "Large spin-orbit torques in Pt/Co-Ni/W heterostructures". United States. doi:10.1063/1.4959958.
@article{osti_22594441,
title = {Large spin-orbit torques in Pt/Co-Ni/W heterostructures},
author = {Yu, Jiawei and Qiu, Xuepeng and Legrand, William and Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg},
abstractNote = {The spin orbit torques (SOTs) in perpendicularly magnetized Co-Ni multilayers sandwiched between two heavy metals (HM) have been studied. By exploring various HM materials, we show an efficient enhancement or cancellation of the total SOT, depending on the combination of the two HM materials. The maximum SOT effective field is obtained in Pt/Co-Ni/W heterostructures. We also model our double HM system and show that the effective spin Hall angle has a peak value at certain HM thicknesses. Measuring the SOT in Pt/Co-Ni/W for various W thicknesses confirms an effective spin Hall angle up to 0.45 in our double HM system.},
doi = {10.1063/1.4959958},
journal = {Applied Physics Letters},
number = 4,
volume = 109,
place = {United States},
year = 2016,
month = 7
}
  • Spin-orbit torques (SOTs) are studied in perpendicularly magnetized ultrathin Co films sandwiched between two heavy metals, Pt and Ta. A significant enhancement of the Slonczewski-like torque is achieved by placing dissimilar metals with opposite spin Hall angles on opposite sides of the ferromagnet. SOTs were characterized through harmonic measurements and the contribution by the Ta overlayer was isolated by systematically varying its thickness. An effective spin Hall angle of up to 34% is observed, along with a sizable field-like torque that increases with increasing Ta layer thickness. Current-induced switching measurements reveal a corresponding increase in switching efficiency, suggesting that bymore » engineering both interfaces in trilayer structures, the SOTs can be significantly improved.« less
  • We have studied the spin-orbit torques in perpendicularly magnetized Hf/CoFeB/MgO system, by systematically varying the thickness of Hf underlayer. We have observed a sign change of effective fields between Hf thicknesses of 1.75 and 2 nm, indicating that competing mechanisms, such as the Rashba and spin Hall effects, contribute to spin-orbit torques in our system. For larger Hf thicknesses (>2 nm), both the components of spin-orbit torques arise predominantly from the bulk spin Hall effect. We have also confirmed these results using spin-orbit torque induced magnetization switching measurements. Our results could be helpful in designing Hf based SOT devices.
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