High valley polarization near Dirac point in graphene-based superlattice

Abstract

Abstract We studied the valley-dependent energy band and transport property of graphene-based magnetic-strain superlattice. The dispersion relations obtained by using the transfer matrix method show that the band gaps and the Dirac points for K and K ′ valleys of the system have different characters, which plays a basic role in the valley-dependent transport. Through careful analysis of the energy band, we found that the system not only has a zero-energy Dirac point but also a lot of new finite-energy Dirac points. Significantly, we are also able to accurately determine the location of these Dirac points. The emergence of these Dirac points has greatly affected the valley polarization of the system. This provides theoretical guidance for modulating valley-related transport and enhancing valley polarization.