Spin accumulation probed in multiterminal lateral all-metallic devices

TL;DR

This study investigates spin accumulation in a multiterminal aluminium device with cobalt electrodes, measuring spin relaxation length and polarization at different temperatures using magnetic configuration analysis.

Contribution

It introduces a method to identify magnetic configurations and extract spin relaxation parameters in all-metallic devices through spin accumulation measurements.

Findings

Spin relaxation length is 400 ± 50 nm at low temperature.

Interface spin polarization is 10 ± 1% at low temperature.

Spin relaxation length is 350 ± 50 nm at room temperature.

Abstract

We study spin accumulation in an aluminium island, in which the injection of a spin current and the detection of the spin accumulation are done by means of four cobalt electrodes that connect to the island through transparent tunnel barriers. Although the four electrodes are designed as two electrode pairs of the same shape, they nonetheless all exhibit distinct switching fields. As a result the device can have several different magnetic configurations. From the measurements of the amplitude of the spin accumulation, we can identify these configurations, and using the diffusion equation for the spin imbalance, we extract the spin relaxation length $\lambda_\mathrm{sf} = 400 \pm 50$~nm and an interface spin current polarization $P = (10 \pm 1)%$ at low temperature and $\lambda_\mathrm{sf} = 350 \pm 50$~nm, $P = (8 \pm 1)%$ at room temperature.