Spin current induced by alternating field in a magnetic-oscillating quantum dot

The spin current driven by an alternating field in a magnetic-oscillating quantum dot system coupled to single metal electrode is investigated. The Keldysh's nonequilibrium Green function technique is used to find the general formulas of the time-averaged spin current and its differential. We find that for a given rotating frequency, the spin current increases rapidly and shows a series of steps with increasing driven frequency. As the driven frequency is further increasing, the spin current can be significantly enhanced and approaches a stable value. The influence of the gate voltage and temperature on the spin current is examined in detail.