Spin-polarized currents through interacting quantum wires with nonmagnetic leads

We study the performance of a quantum wire spin filter that is based on the Rashba spin-orbit interaction in the presence of the electron-electron interaction. The finite-length wire is attached to two semi-infinite nonmagnetic leads. Analyzing the spin polarization of the linear conductance at zero temperature, we show that spin filtering is possible by adequate tuning of the system parameters first considering noninteracting electrons. Next, the functional renormalization-group method is used to capture correlation effects induced by the Coulomb interaction. For short wires we show that the energy regime in which spin polarization is found is strongly affected by the Coulomb interaction. For long wires we find the power-law suppression of the total conductance on low-energy scales typical for inhomogeneous Luttinger liquids while the degree of spin polarization stays constant.