Weijiang Gong

Tunable pure spin currents in a triple-quantum-dot ring

Electronic transport through a triple-quantum-dot ring with three terminals is theoretically studied. By introducing local Rashba spin-orbit interaction on an individual quantum dot, we calculate the charge and spin currents in one lead. We find that a pure spin current without an accompanying charge current appears even at zero magnetic field case. The polarization direction of the spin current can be inverted by altering the bias voltage. In addition, by tuning the magnetic field strength, the charge and spin currents reach their respective peaks alternately.

Spin accumulation in a multi-arm Aharonov-Bohm-Fano interferometer

The spin accumulation properties of a multi-arm Aharonov-Bohm-Fano interferometer are investigated by considering spin bias in the leads. We find that the spin accumulations in the quantum dots (QDs) can be adjusted independently by changing the magnetic fluxes through the sub-rings formed by the QD-lead and lead-lead couplings. When analyzing the quantum interference effect, we find that the Aharonov-Bohm-Fano interference mechanism is a necessary condition to realize the spin accumulation. Based on the numerical results, we propose that such a structure has a significant potential as a candidate for a spin-manipulating device.

Spin separation in a quantum dot ring driven by a temperature bias

By introducing local Rashba spin-orbit interaction in a three-terminal quantum dot ring, we calculate the currents induced by thermoelectric effect. It shows that, when a temperature bias is applied between the source and drains, there emerge apparent spin currents in the two drains. We find, via adjusting the structure parameters, that an electron from the source will choose its drain according to its spin index. Due to the advances in nanodevice fabrication, this structure can be constructed, and then we believe that it can be a candidate of the spin-manipulating device.