Cascade of Y -shaped spin filters in InGaAs/InAs/InGaAs quantum wells

An all-electrical semiconductor device for generating and detecting spin-polarized currents with a two-stage cascade of three-terminal spin filters is discussed, where the first stage serves as the spin polarizer and the second stage serves as the detector. Transport simulations show imbalanced output conductance for higher-order subbands, independent of the spin-orbit coupling strength. However, when only the lowest subband is occupied the simulations show that the conductance asymmetry is spin-orbit dependent. Therefore, the conductance asymmetry of the lowest subband can be used to indicate spin polarization. Based on the simulations an experimental device to measure the spin-dependent conductance asymmetry is proposed.