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arXiv · 2112.12112

Spin Hall Effect in a Thin Pt Film

Rohit S. Nair·Max S. Rang·Paul J. Kelly
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Abstract

A density-functional-theory based relativistic scattering formalism is used to study charge transport through thin Pt films with room temperature lattice disorder. A Fuchs-Sondheimer specularity coefficient $p \sim 0.5$ is needed to describe the suppression of the charge current at the surface even in the absence of surface roughness. The charge current drives a spin Hall current perpendicular to the surface. Analysing the latter with a model that is universally used to interpret the spin Hall effect in thin films and layered materials, we are unable to recover values of the spin-flip diffusion length $l_{\rm sf}$ and spin Hall angle $\Theta_{\rm sH}$ that we obtain for bulk Pt using the same approximations. We trace this to the boundary conditions used and develop a generalized model that takes surface effects into account. A reduced value of $\Theta_{\rm sH}$ at the surface is then found to describe the first-principles transport results extremely well. The in-plane spin Hall effect is substantially enhanced at the surface.

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Rohit S. Nair, Max S. Rang, Paul J. Kelly. 2021-12-22. Spin Hall Effect in a Thin Pt Film. https://doi.org/10.1103/physrevb.104.l220411

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