Spin injection, accumulation and spin precession in a mesoscopic non-magn etic metal island

TL;DR

This paper experimentally investigates spin accumulation, injection, and precession in a mesoscopic aluminium island, revealing significant spin signals and quantifying spin relaxation and polarization at room temperature and cryogenic conditions.

Contribution

It provides a comprehensive experimental and theoretical analysis of spin dynamics in a mesoscopic non-magnetic metal island with uniform spin accumulation.

Findings

Spin accumulation signal exceeds aluminium island's Ohmic resistance.

Spin relaxation time of 60 ps at room temperature.

Polarization of 8% with low-resistance tunnel barriers.

Abstract

We experimentally study spin accumulation in an aluminium island with all dimensions smaller than the spin relaxation length, so that the spin imbalance throughout the island is uniform. Electrical injection and detection of the spin accumulation are carried out in a four terminal geometry by means of four cobalt electrodes connected to the island through tunnel barriers. We model the system theoretically and we investigate the role of the ferromagnetic electrodes on the spin accumulation at the limit at which the electron diffusion time can be neglected. We present measurements of spin accumulation at room temperature and at 4.2 K: in both cases the spin accumulation signal is larger than the Ohmic resistance of the aluminium island. From magnetisation precession measurements at room temperature, we extract a spin relaxation time of 60 ps and a polarisation P = 8% for tunnel barriers with resistances as low as 20 \Omega\mu m^2.