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Anatomy of spin-orbit-torque-assisted magnetization dynamics in Co/Pt bilayers: Importance of the orbital torque

Harshita Devda1,*, András Deák2, Leandro Salemi3, Levente Rózsa4,2, László Szunyogh2,5, Peter M. Oppeneer3, and Ulrich Nowak6

  • *Contact author: harshita.devda@uni-konstanz.de
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Phys. Rev. B 112, 144438 – Published 27 October, 2025

DOI: https://doi.org/10.1103/5k5n-4hr7

Abstract

Understanding the mechanism driving magnetization switching in spin-orbit-torque-assisted devices remains a subject of debate. While originally attributed to the spin Hall effect and spin Rashba-Edelstein effect, recent discoveries related to orbital moments induced by the orbital Hall effect and the orbital Rashba-Edelstein effect have added complexity to the comprehension of the switching process in nonmagnet/ferromagnet bilayers. Addressing this challenge, we present a quantitative investigation of a Pt/Co bilayer by employing atomistic spin dynamics simulations, incorporating the proximity-induced moments of Pt, as well as electrically induced spin and orbital moments obtained from first-principles calculations. Our layer-resolved model elucidates the dampinglike and fieldlike nature of the induced moments by separating them according to their even and odd magnetization dependence. In addition to demonstrating that a larger fieldlike spin-orbit-torque contribution comes from previously disregarded induced orbital moments, our work highlights the necessity of considering interactions with Pt-induced moments at the interface, as they contribute significantly to the switching dynamics.

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Phys. Rev. B 112, 144438– Published 27 October, 2025
  • Received 22 May 2025
  • Revised 20 August 2025
  • Accepted 3 October 2025
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