Three-dimensional distribution of spin-polarized current inside (Cu/Co) pillar structures

Within diffusive transport, we calculate three-dimensional current distribution inside a $(\mathrm{Cu}∕\mathrm{Co})$ pillar structure, where the pillar is terminated either by an infinitely large $\mathrm{Cu}$ layer, or by a $\mathrm{Cu}$ wire with a cross-sectional area identical to that of the pillar. We study how pillar terminations (infinitely large or finite) influence the magnitudes and inhomogeneities of the spin-polarized current and electrochemical potential. We found that infinitely large $\mathrm{Cu}$ layers work as strong spin scatterers, increasing the magnitude of spin-polarized current inside the pillar twice and reducing spin accumulation to nearly zero. The inhomogeneities of the electrochemical potential are found to be much smaller than those of the spin-polarized current.