Nonequilibrium magnetic polarization and spin currents controlled by gate voltage in a ferromagnetic single-electron transistor

摘要

Spin-dependent electronic transport in a single-electron transistor with ferromagnetic external electrodes and nonmagnetic central part (island) is analyzed theoretically in the sequential tunneling and cotunneling regimes. Nonequilibrium magnetic polarization of the island due to spin accumulation (spin splitting of the chemical potential) is taken into account. The accumulation takes place when the spin relaxation time on the island is sufficiently long. The crossover from slow to fast spin relaxation limits is also analyzed. Magnetic polarization of the island and spin polarization of the flowing current are examined as a function of the gate and transport voltages.