The Effects of the Interdot and Lead-Dot Coupling on the Spin and Charge Current Through a Triple-Quantum-Dot Ring

Based on Green's function formalism, we investigate the effects of interdot and lead-dot coupling on the charge and spin current through a triple-quantum-dot ring structure, where each dot is connected to a semi-infinite lead. The results show that in weak (strong) interdot coupling regime, by increasing the interdot coupling strength t, the output current increases (decreases), approaching a maximum (nearly constant) value. Besides, the on-site energy of quantum dots (QDs), and also the electron-electron interaction termed as a coulomb blockade one, can be effective on the output current versus t. In addition, by increasing the lead-dot coupling strength, the occupation number of the corresponding QD decreases and so the current through connected lead, increases. Moreover, by tuning the parameters such as Rashba spin-orbit interaction, on-site energies of dots and magnetic flux inside the ring, one can control and manipulate the spin-dependent output currents as a function of the lead-dot and interdot coupling strength to obtain a pure spin current, and also reveal the spin-flip effect through the output lead, therefore, the proposed device can be useful in various spintronic nanoscale applications.