Two-Terminal Spin Filter Using Quantum Dot with Spin-Orbit Interaction in Magnetic Field

We propose a two-terminal spin filter utilizing a quantum dot with spin-orbit interaction and magnetic field. First we examine a quantum dot with two energy-levels, as a minimal model, and obtain an analytical expression for the spin-dependent conductance. When the spacing between the two levels is smaller than the level broadening due to the tunnel coupling to the leads, a largely spin-polarized current is generated around the current peaks of Coulomb oscillation. Next, we perform a numerical simulation using a realistic model for a quantum dot and tunnel barriers and evaluate the efficiency of our spin filter.