Direct electronic measurement of the spin Hall effect

TL;DR

This paper reports the first direct electrical measurement of the spin Hall effect in a metallic conductor, demonstrating spin-to-charge conversion using a ferromagnetic electrode, advancing spintronics technology.

Contribution

It introduces a novel electrical measurement technique for the spin Hall effect in metals, eliminating the need for optical detection methods.

Findings

Observed voltage proportional to perpendicular spin component

Demonstrated spin-to-charge conversion in a metallic conductor

Potential for spintronics devices without magnetic materials

Abstract

The generation, manipulation and detection of spin-polarized electrons in nanostructures define the main challenges of spin-based electronics[1]. Amongst the different approaches for spin generation and manipulation, spin-orbit coupling, which couples the spin of an electron to its momentum, is attracting considerable interest. In a spin-orbit-coupled system, a nonzero spin-current is predicted in a direction perpendicular to the applied electric field, giving rise to a "spin Hall effect"[2-4]. Consistent with this effect, electrically-induced spin polarization was recently detected by optical techniques at the edges of a semiconductor channel[5] and in two-dimensional electron gases in semiconductor heterostructures[6,7]. Here we report electrical measurements of the spin-Hall effect in a diffusive metallic conductor, using a ferromagnetic electrode in combination with a tunnel barrier to inject a spin-polarized current. In our devices, we observe an induced voltage that results exclusively from the conversion of the injected spin current into charge imbalance through the spin Hall effect. Such a voltage is proportional to the component of the injected spins that is perpendicular to the plane defined by the spin current direction and the voltage probes. These experiments reveal opportunities for efficient spin detection without the need for magnetic materials, which could lead to useful spintronics devices that integrate information processing and data storage.