Electron spin polarization along a one-dimensional wire with periodic Rashba and uniform Dresselhaus spin-orbit couplings


We investigate the transmission of an electron spin on a one-dimensional wire with a periodic Rashba spin-orbit couplings (SOC) and a constant contribution from a Dresselhaus SOC. The straight wire is divided into initially uniform segments and the Rashba SOC is turned on every alternating segment. Eigenvalues and eigenfunctions for both without and with Rashba SOC segments are analytically derived. From these obtained values, we numerically calculate the net polarization at the output. We find in our result that regardless of the initial spin orientation, the output polarization turns out to be spin-up polarized. The modulation effect of the segment length of the wire via a periodic Rashba SOC is manifested by the appearance of an energy gap whose width increases with larger Rashba coupling strength. On the other hand, the position of the gap can be tuned by setting the strength of the Dresselhaus SOC. We find that for electrons with Fermi energies falling within this gap, the output spin current is unpolarized.