Spin-polarized current diode effect of a quantum dot in a rotating magnetic field

The spin-pump effects on the spin-dependent transport through a quantum dot (QD) subjected to a rotating magnetic field are theoretically studied. In the absence of the rotating magnetic field, the current polarization is zero for a bias within the Coulomb blockade regime and a relatively large value for other biases. However, in the presence of the rotating magnetic field applied to the QD, the current polarization becomes a finite value even in the Coulomb blockade regime, since the spin-pump effects can suppress the spin accumulation greatly. Furthermore, the current polarization can even change its sign when the bias increases to beyond the Coulomb blockade regime at sizable Zeeman splitting. Therefore, the device can operate as a tunable spin-polarized current diode by using the rotating magnetic field.