▎ 摘　　要

Considering that the strong spin-orbit interaction of a topological insulator (TI) makes it possible to generate large spin polarization and that graphene with weak spin-orbit coupling can transmit spin information over large distances, we propose a topological insulator-graphene junction (TIG) for spin and charge transport. We find that the TI in the TIG can inject a finite electrically induced net spin current into the graphene without any of the conditions necessary in traditional spin-generation devices. The magnitude of the spin current can be tuned with an applied bias voltage. These findings are useful for developing spintronics. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769813]