Quantum interference and spin polarization on Rashba double quantum dots embedded in a ring

We report on the quantum interference and spin accumulation on double quantum dots with Rashba spin-orbit coupling and electron-electron interaction based on the Keldysh nonequilibrium Green's function formalism. It is shown that Rashba spin-orbit interaction can strongly affect the conductance spectrum. By gradually increasing the Rashba parameter from zero, Fano resonances in strong overlap regime continuously evolve to resolve antiresonances. This transition is ascribed to the phase shift of couplings between molecular states and the lead due to spin precession. We also show that both bias and Rashba effects strengthen the induced spin polarization in this device. For particular energy position, up- and down-spin electron occupations can intersect to form a crossing point. Spin polarization on different sides of this point has opposite sign in consequence. The magnitude and direction of spin polarization are therefore controllable by tuning the dot levels and the Rashba parameter through gates.