Thermoelectric Phenomena in a Quantum Dot Attached to Ferromagnetic Leads in Kondo Regime

We have studied the thermoelectric properties through ferromagnetic leads-QD coupled system (F-QD-F) in the Kondo regime by nonequilibrium Green's functions method. The spin-flip effect induced by ferromagnetic leads and Kondo effect influence the thermoelectric properties significantly. The peak-valley structure emerges at the low temperature due to Kondo resonance, and the peak-valley structure also relies on the polarization angle theta, the spin-dependent linewidth function Gamma(gamma sigma) and the energy level of QD epsilon(d). Novel resonant peak also emerges in the curve of ZT(c) versus polarization angle theta. The Kondo effect suppresses the figure of merit ZT(c) and the spin-dependent figure of merit ZT(s). In addition, the spin-dependent figure of merit ZT(s) is relate with the gap between Gamma(gamma up arrow) and Gamma(gamma down arrow).