Characterizing spin transport: detection of spin accumulation via magnetic stray field

TL;DR

This paper proposes a direct method to measure spin transport parameters in metals by detecting magnetic stray fields generated by spin accumulation, offering a potentially more straightforward alternative to indirect magnetoresistance measurements.

Contribution

It introduces a novel approach to characterize spin transport by using magnetic stray field detection, bypassing the need for interfacial property assumptions.

Findings

Stray fields from spin accumulation are detectable with current technology.

The method provides a direct measurement of spin diffusion length and spin Hall angle.

Spatial profiles of stray and Oersted fields are characterized.

Abstract

Spin transport in electric conductors is largely determined by two material parameters - spin diffusion length and spin Hall angle. In metals, these are typically determined indirectly by probing magnetoresistance in magnet/metal heterostructures, assuming knowledge of the interfacial properties. We suggest profiling the charge current induced spin Hall spin accumulation in metals, via detection of the magnetic stray field generated by the associated static magnetization, as a direct means of determining spin transport parameters. We evaluate the spatial profile of the stray field as well as the Oersted field generated by the charge current. We thus demonstrate that such a charge current induced spin accumulation is well within the detection limit of contemporary technology. Measuring the stray fields may enable direct access to spin-related properties of metals paving the way for a better and consistent understanding of spin transport therein.