Disorder and localization of electrons in bilayer graphene

We investigate localization behavior of electron states in bilayer graphene formed with the Bernal stacking in the presence of various types of disorder (site-energy, in-plane hopping and inter-plane hopping) by the use of the transfer matrix method. It is found that all the states are localized at various kinds of disorder (site-energy, in-plane hopping and inter-plane hopping) except that in the case of inter-plane-hopping disorder the states at the zero energy are critical. The implications of the results are discussed.