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Interfacial contributions to spin-orbit torque and magnetoresistance in ferromagnet/heavy-metal bilayers

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K. D. Belashchenko, Alexey A. Kovalev, M. Van Schilfgaarde

Original languageEnglish
Article number020407
JournalPhysical Review B
Volume101
Issue number2
DOIs
Publication statusPublished - 17 Jan 2020

King's Authors

Abstract

The thickness dependence of spin-orbit torque and magnetoresistance in ferromagnet/heavy-metal bilayers is studied using the first-principles nonequilibrium Green's function formalism combined with the Anderson disorder model. A systematic expansion in orthogonal vector spherical harmonics is used for the angular dependence of the torque. The dampinglike torque in Co/Pt and Co/Au bilayers can be described as a sum of the spin-Hall contribution, which increases with thickness in agreement with the spin-diffusion model, and a comparable interfacial contribution. The magnetoconductance in the plane perpendicular to the current in Co/Pt bilayers is of the order of a conductance quantum per interfacial atom, exceeding the prediction of the spin-Hall model by more than an order of magnitude. This suggests that the "spin-Hall magnetoresistance," similarly to the dampinglike torque, has a large interfacial contribution unrelated to the spin-Hall effect.

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