• Letter

Nontrivial torque generation by orbital angular momentum injection in ferromagnetic-metal/Cu/Al2O3 trilayers

Junyeon Kim, Dongwook Go, Hanshen Tsai, Daegeun Jo, Kouta Kondou, Hyun-Woo Lee, and YoshiChika Otani
Phys. Rev. B 103, L020407 – Published 15 January 2021
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Abstract

Efficient electrical generation of torque is desired to develop innovative magnetic nanodevices. The torque can be generated by charge to spin conversion of heavy-metal layers through their strong spin-orbit interaction followed by the injection of the converted spin into adjacent ferromagnetic layers. However heavy atomic elements indispensable for this torque generation scheme are often incompatible with device mass production processes. Here we demonstrate efficient torque generation without heavy elements in ferromagnetic metal/Cu/Al2O3 trilayers. Despite the absence of heavy elements, their effective spin Hall conductivity can be one order of magnitude larger than those of heavy-metal based multilayers. Properties of the measured torque deviate from those of the spin-injection induced torque and are consistent instead with a recently proposed torque mechanism based on orbital angular momentum injection. Our results demonstrate a direction for magnetic nanodevices based on the orbital angular momentum injection.

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  • Received 28 April 2020
  • Revised 7 December 2020
  • Accepted 15 December 2020

DOI:https://doi.org/10.1103/PhysRevB.103.L020407

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Junyeon Kim1,*, Dongwook Go2,3,4,5, Hanshen Tsai1,6, Daegeun Jo2, Kouta Kondou1, Hyun-Woo Lee2,7,†, and YoshiChika Otani1,6,‡

  • 1Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
  • 2Deparment of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
  • 3Basic Science Research Institute, Pohang University of Science and Technology, Pohang 37673, Korea
  • 4Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52428 Jülich, Germany
  • 5Institute of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany
  • 6Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277–8581, Japan
  • 7Asia Pacific Center for Theoretical Physics, Pohang 37673, Korea

  • *junyeon.kim@riken.jp
  • hwl@postech.ac.kr
  • yotani@issp.u-tokyo.ac.jp

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Issue

Vol. 103, Iss. 2 — 1 January 2021

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