科研之友
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摘要
The reversal spin-polarised current-voltage (J-v) spectra and negative differential conductivity (NDC) in a four-quantum-dot ring embedded in the Aharonov-Bohm interferometer are investigated theoretically by means of non-equilibrium Green function technique, when introducing a local Rashba spin-orbit interaction and a finite bias voltage. It shows that the coupling strength between the quantum dots and the leads is the main contributing factor to the step effect of the spin-polarised J-v spectra at zero temperature, the anti-resonance is the formation mechanism of the step effect and the intra-dot Coulomb interaction raises a new step in the spin-polarised J-v spectra. Furthermore, by adjusting the bias voltage applied on the leads, the charge current and spin current move in opposite direction and the polarisation direction is reversed. In the case of the finite energy bandwidth approximation, an NDC appears in a finite bias region, but the step effect is disappeared at the same time. Based on the numerical results, such a model can be applied in design of high frequency current oscillator device.
