Creation and detection of spin-polarized current using quantum point contact with spin-orbit interaction

We have proposed that quantum point contacts (QPCs) can be a useful tool for producing spin-polarized currents in the presence of Rashba spin-orbit (SO) interaction [J. Phys. Soc. Jpn. 74, 1934 (2005)]. No magnetic field is required. When the conductance through a QPC is quantized in units of 2e²/h, the current is spin-polarized in the transverse direction. This spin polarization, which can be larger than 50% in InGaAs heterostructures, is elucidated using the S-matrix formalism. We also examine transport properties of a QPC connected to a ferromagnetic lead and show how to detect the spin-polarized current from the QPC.