Contribution of defects to the spin relaxation in copper nanowires

TL;DR

This paper investigates how defects, phonons, and magnetic impurities affect spin relaxation in copper nanowires, revealing key scattering mechanisms and potential ways to enhance spin transport in metallic nanostructures.

Contribution

It quantifies defect contributions to spin relaxation in copper nanowires and identifies grain boundaries and magnetic impurities as major factors affecting spin transport.

Findings

Temperature dependence of spin-flip scattering is due to phonons.

Grain boundaries are the main temperature-independent defect contribution.

Magnetic impurities cause a maximum in spin diffusion length at low temperatures.

Abstract

The contributions to the spin relaxation in copper (Cu) nanowires are quantified by carefully analyzing measurements of both charge and spin transport in lateral spin valves as a function of temperature and thickness. The temperature dependence of the spin-flip scattering solely arises from the scattering with phonons, as in bulk Cu, whereas we identify grain boundaries as the main temperature-independent contribution of the defects in the nanowires. A puzzling maximum in the spin diffusion length of Cu at low temperatures is found, which can be explained by the presence of magnetic impurities. The results presented here suggest routes for improving spin transport in metallic nanostructures, otherwise limited by confinement effects.