First-principles calculation of the nonadiabatic spin transfer torque in Ni and Fe

Keith Gilmore, Ion Garate, Allan H. MacDonald, and M. D. Stiles
Phys. Rev. B 84, 224412 – Published 16 December 2011

Abstract

The magnetization dynamics of a ferromagnet subjected to an electrical current are described by an extension of the Landau-Lifshitz-Gilbert equation that contains two additional terms, the adiabatic and nonadiabatic spin-transfer torques. First-principles calculations of the nonadiabatic spin-transfer torque parameter β for bcc iron and fcc nickel show that β is related to and typically of the same order as α, the damping constant, but is distinct from it. Calculations as a function of the ratio of spin-dependent scattering rates show that (1) the minimum of the damping constant as a function of scattering rate does not change significantly, and (2) when the polarization of the current approaches zero, β can become large but the implied domain-wall velocity does not.

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  • Received 6 October 2011

DOI:https://doi.org/10.1103/PhysRevB.84.224412

©2011 American Physical Society

Authors & Affiliations

Keith Gilmore1,2, Ion Garate3, Allan H. MacDonald4, and M. D. Stiles5

  • 1National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA
  • 2The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 3Department of Physics, Yale University, New Haven, Connecticut 06520, USA
  • 4Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
  • 5Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA

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Issue

Vol. 84, Iss. 22 — 1 December 2011

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