Spin-Diffusion Lengths in Dilute Cu(Ge) and Ag(Sn) Alloys

TL;DR

This study measures spin diffusion lengths in dilute Cu(Ge) and Ag(Sn) alloys using CPP spin-valves, validating Valet-Fert theory and providing new data for spin-orbit interactions in these materials.

Contribution

First direct measurements of spin diffusion lengths in dilute Cu(Ge) and Ag(Sn) alloys using CPP spin-valves, confirming theoretical models and estimating spin-orbit cross-sections.

Findings

lsf(Cu2%Ge) = 117+10-6 nm

lsf(Ag4%Sn) = 39 +/- 3 nm

Validation of Valet-Fert theory for layer thicknesses multiple times larger

Abstract

We use current-perpendicular-to-plane (CPP) exchange-biased spin-valves to directly measure spin diffusion lengths lsf for N = Cu(2.1 at.%Ge) and Ag(3.6 at.%Sn) alloys. We find lsf(Cu2%Ge)) = 117+10-6 nm and lsf(Ag4%Sn)= 39 +/- 3 nm. The good agreement of this lsf(Cu2%Ge) with the value lsf(Cu2%Ge) = 121 +/- 10 nm derived from an independent spin-orbit cross-section measurement for Ge in Cu, quantitatively validates the use of Valet-Fert theory for CPP-MR data analysis to layer thicknesses several times larger than had been done before. From the value of lsf(Ag4%Sn), we predict the ESR spin-orbit cross-section for Sn impurities in Ag.