A molecular device: providing remarkable spin filtering effect due to the central molecular stretched by lateral zigzag graphene nanoribbon electrodes

Through density functional theory, we studied molecular device composed of a single tetrathiafulvalene (TTF) molecule connected with the zigzag graphene nanoribbon electrodes by four different junctions. Interestingly, some devices exhibit half-metallic behavior and can bring out perfect spin filtering effect and remarkable negative differential resistance behavior. The current-voltage characteristics shows that these four devices possess different spin current values. We find that the TTF molecules have all been stretched during interaction with the electrodes in four devices. This leads to three devices’ Fermi levels down-shifted into the valence-band, so these devices exhibit half-metallic properties. The underlying mechanisms of different spin current values are attributed to the different electron transmitting ways (by chemical bond or through hopping between atoms). These results suggest that the device properties and conductance are controlled by different junctions. Our work predicts an effective way for designing high performance spin-injected molecular devices.