Edge states and enhanced spin-orbit interaction at graphene/graphane interfaces

We study the electronic properties of interfaces between graphene and graphane, a hydrogenated version of graphene. It is shown that these interfaces are useful for creating an effective edge for the π-electrons of graphene. If the interface is oriented along a zigzag direction, edge states are found. We consider two different interface types, corresponding to usual zigzag and bearded graphene edges. It is shown that, because of a broken symmetry, the spin-orbit interaction is strongly amplified by the graphene/graphane interface and that the edge states are particularly susceptible to this amplification. As an application, we propose a device which is capable of converting spin polarizations to valley polarizations and vice versa. Exploiting the amplification of the spin-orbit interaction, this conversion may be performed at temperatures near one Kelvin. We show that these edge states give rise to quantum spin and/or valley Hall effects.