Spin-sensitive charge oscillation in a single-molecule transistor

A molecular spintronics device is considered as a highly promising candidate for the quantum hardware in the field of practical quantum information applications. Within this field, local objects always obey the Coulomb blockade effect, where electrons occupy molecular orbitals monotonically in a step-like manner as the gate voltage sweeps. Herein, based on a single-molecule transistor in an external magnetic field, we predict that the charge occupation of both spin channels may show nonmonotonic filling, characterized by a spin-sensitive charge oscillation, contravening the standard Coulomb blockade behavior. We attribute this nonmonotonicity to the competition among the Zeeman effect, the many-body effect, and the symmetry of the quantum states. To obtain significant oscillations, strong electron–electron interaction and low temperature are prerequisites. We demonstrate that the oscillation goes against the spin-polarized transport, and for appropriate parameters, the transistor may act as a perfect electronically-manipulable bidirectional molecular spintronics device. To implement such an ideal, the state-of-the-art numerical renormalization group method is adopted, and an experimental proposal to test these predictions is suggested.