Eur. Phys. J. B (2015) 88: 54
https://doi.org/10.1140/epjb/e2015-50732-3

Regular Article

Valley polarized insulator-metal transition and valley filtering effect in graphene

¹ College of Science, Hohai University, Nanjing 210098, P.R. China
² National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P.R. China

^a e-mail: caojielunwen00@163.com

Received: 21 October 2014
Received in final form: 21 December 2014
Published online: 9 March 2015

Abstract

We investigate the properties of a graphene system taking into account both the on-site Coulomb repulsion and the Rashba spin-orbit coupling caused by a transverse electric field by using a mean-field approximation of the Hubbard model. It is found that by increasing the strength of the Rashba spin-orbit coupling, the system with a strong Coulomb interaction can successively go through three phases: valley polarized insulator, valley polarized metal, and normal metal, in which the first two phases are new ones characterized by their specific band structures. Hence, a valley polarized insulator-metal phase transition can occur by changing the strength of the spin-orbit coupling in this system. We propose a mechanism of valley filter based on the gated valley polarized insulator, in which a net K or K′ valley current can be obtained.