Molecular spintronics using single-molecule magnets under irradiation

We theoretically investigate a single-molecule magnet (SMM) grafted to a quantum dot in contact with metallic leads and interacting with a resonant electromagnetic radiation. We explore both the explicit time-dependent behavior and the steady-state current-voltage characteristics of the device when the source lead is ferromagnetic. At zero-bias voltage, a net current is pumped through the device with the source spin current being reversed and amplified in the drain lead; this effect also persists for nonzero bias. We explain this effect in terms of spin transitions in the nanomagnet induced by the resonant radiation followed by their subsequent relaxation via spin-asymmetric charge-transfer processes. We demonstrate that the same effects are recovered in the time-averaged current when the device interacts with pulsed resonant radiation. Moreover, within the pulsed irradiation regime, appropriate choices of pulse length and wait times are shown here to allow the detection of coherent Rabi oscillations of the SMM spin states, via time-averaged spin current measurements.