Electrically tunable spin diode effect in a tunneling junction of quantum dot

Control over the tunneling current in spintronic devices by electrical methods is an interesting topic, which is experiencing a burst of activity. In this paper, we theoretically investigate the transport property of electrons in a spin-diode structure consisting of a single quantum dot(QD) weakly coupled to one nonmagnetic(NM) and one half-metallic ferromagnet(HFM) leads, in which the QD has an artificial atomic nature. By modulating the gate voltage applied on the dot, we observe a pronounced decrease in the current for one bias direction. We show that this rectification is spin-dependent, which stems from the interplay between the spin accumulation and the Coulomb blockade on the quantum dot. The degree of such spin diode behavior is fully and precisely tunable using the gate and bias voltages. The present device can be realized within current technologies and has potential application in molecular spintronics and quantum information processing.