Spin Pumping from a Quantum Dot in the Presence of Decoherence

We study the pumped spin current of an interacting quantum dot tunnelcoupled to a single lead in the presence of electron spin resonance (ESR) field. The spin decoherence in the dot is included by the Buttiker approach. Using the nonequilibrium Green's function technique, we show that ESR-induced spin flip can generate finite spin current with no charge transport. Both the Coulomb interaction and spin decoherence decrease the amplitude of spin current. The dependence of pumped spin current on the intensity and frequency of ESR field, and the spin decoherence is discussed.