Pure spin and spin polarized currents in the benzene molecule connected to three graphene leads

n this work, we present a theoretical study of a molecular junction based on benzene molecule at the center of the junction with three semi infinite graphene nanoribbons as external terminals to explore spin dependent current properties by using Green´s function method. The exchange magnetic field is exerted on the molecular junction in order to break the degeneracy of electrons with spin up and spin down states. It is shown that by changing chemical potential and choosing a proper geometry of the structure we can control the direction of spin dependent electron current such that in one of the external terminals electrons with different spin states flow in opposite directions; therefore, in that terminal the pure spin current can be attainable. In addition, we show that by considering another form of benzene Y-shape junction and by readjusting chemical potentials of the external terminals, we can set the system in a way that a totally unpolarized incoming spin current split into spin up and spin down currents which transmit through different output terminals. In this case, the proposed system can be considered as a Stern-Gerlach device.