One of the challenges in valleytronics is how to effectively manipulate the valley degree of freedom of electrons in graphene. We propose to use a pseudovalley exchange field to rotate the valley, which arises in a graphene superlattice (GS) structure due to the two inequivalent $K$ and $K^{\prime }$ valleys folded and coupled together. The valley is shown to precess periodically in real space, but the precession itself has a spatial anisotropy unless the GS structure still possesses a rotational symmetry. The pseudovalley exchange field exclusively determines the valley precession periodicity when the electron energy is much larger than the possible GS energy gap. Our findings provide a practical way to control and manipulate the valley degree of freedom in graphene.

• Received 8 June 2015

DOI:https://doi.org/10.1103/PhysRevB.92.075419