Thermoelectric effects in double quantum dots with spin dependent interdot coupling and two ferromagnetic electrodes

We study thermoelectric effects in double quantum dots with spin dependent interdot coupling attached to ferromagnetic electrodes. Thermoelectric and thermo-spin coefficients are calculated by means of the non-equilibrium Green function in the linear response regime. It is found that in the absence of spin accumulation in leads, the thermal conductance is significantly enhanced at high temperature due to the bipolar effect and the thermoelectric coefficients are strongly dependent on the spin-dependent interdot coupling, the relative magnetic configurations and the spin polarization in leads, and present different variation trend when the spin-up levels and spin-down levels cross the Fermi level. The intradot Coulomb interaction enhances the thermoelectric efficiency, the peak value of figure of merit can reach its maximum at a appropriate temperature and that the maximum increases with Coulomb interaction increasing. In the presence of spin accumulation in leads, The charge figure of merit is much lower than appropriate figure of merit determined in the case without spin accumulation. Moreover, The spin figure of merit is more larger than the charge figure of merit at certain specific energy, and a pure spin current can be obtained.