Transport through a single discrete level for non-collinear magnetic polarizations of the electron reservoirs

Spin-polarized transport through a non-interacting single-level quantum dot coupled to two ferromagnetic leads with non-collinear magnetizations is analyzed theoretically by the non-equilibrium Green function technique. It is shown that spin of an electron that has tunnelled on the dot precesses around an effective exchange field before it leaves the dot. The exchange field originates from interaction between the electron and external electrodes. Electric current, tunnel magnetoresistance, and average value of spin accumulated on the dot are calculated for an arbitrary angle between magnetic moments of the electrodes.