A charge-current switch manipulated by the macroscopic quantum coherence of a single-molecule magnet

We report a theoretical analysis of electron transport through a quantum dot with an embedded biaxial single-molecule magnet, which is coupled to ferromagnetic electrodes of parallel and antiparallel magnet-configurations. For the antiparallel configuration of complete polarization it is shown that the originally prohibited electron transport can be opened up by the macroscopic quantum coherence of the molecular magnet, which provides a spin-flipping mechanism. The charge-current and differential conductance are controllable by variation of the magnitude and orientation of an external magnetic field, which in turn manipulates the macroscopic quantum coherence of the molecular magnet. Moreover, the transport can be switched off at particular values of the magnetic field, where the tunnel splitting is quenched by the quantum phase interference of tunnel paths.The transport current and differential conductance as functions of the electrode-polarization and magnetic field are extensively studied, which may be useful in practical applications. A new transport channel is found in the completely polarized parallel-configuration induced by the tunnel splitting of molecular magnet and resonance-peak splits of the conductance are observed in non-completely polarized configurations. 75.50.Xx Molecular magnets.