Spin torque study of the spin Hall conductivity and spin diffusion length in platinum thin films with varying resistivity

Minh-Hai Nguyen; D. C. Ralph; R. A. Buhrman

doi:10.1103/PhysRevLett.116.126601

paper

Spin torque study of the spin Hall conductivity and spin diffusion length in platinum thin films with varying resistivity

arXiv:1512.06931 · doi:10.1103/PhysRevLett.116.126601

Abstract

We report measurements of the spin torque efficiencies in perpendicularly-magnetized Pt/Co bilayers where the Pt resistivity $ρ_{P t}$ is strongly dependent on thickness $t_{P t}$ . The damping-like spin Hall torque efficiency per unit current density, $ξ_{D L}^{j}$ , varies significantly with $t_{P t}$ , exhibiting a peak value $ξ_{D L}^{j} = 0.12$ at $t_{P t} = 2.8 - 3.9$ nm. In contrast, $ξ_{D L}^{j} / ρ_{P t}$ increases monotonically with $t_{P t}$ and saturates for $t_{P t} > 5$ nm, consistent with an intrinsic spin Hall effect mechanism, in which $ξ_{D L}^{j}$ is enhanced by an increase in $ρ_{P t}$ . Assuming the Elliott-Yafet spin scattering mechanism dominates we estimate that the spin diffusion length $λ_{s} = (0.77 \pm 0.08) \times 1 0^{- 15} Ω m^{2} / ρ_{P t}$ .

Submitted to PRL

Spin torque study of the spin Hall conductivity and spin diffusion length in platinum thin films with varying resistivity

Abstract

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