A new type of spin-current filter is proposed, which consists of a single-molecule magnet (SMM) coupled to two normal metal electrodes. It is shown that this tunneling junction can generate a highly spin-polarized current, whose spin polarization can be switched by the magnetic field and gate voltage applied to the SMM. Such a spin switching in the SMM tunnel junction arises from the spin-selected single electron resonant tunneling via the lowest unoccupied molecular orbit of the SMM. And the electron current spectrum in absences of external magnetic field is still spin-polarized, which can help us to judge if the molecule’s spin state has reach to the ground-state doublet |±S). This device can be realized with current technologies and may have practical use in spintronics and quantum information.
PACS numbers: 72.25.-b, 75.50.Xx, 85.75.-d