We investigate the transverse electric field (E) dependence of the ν=0 quantum Hall state (QHS) in dual-gated graphene bilayers in high magnetic fields. The longitudinal resistivity (ρxx) measured at ν=0 shows an insulating behavior which is strongest in the vicinity of E=0, and at large E-fields. At a fixed perpendicular magnetic field (B), the ν=0 QHS undergoes a transition as a function of E, marked by a minimum, temperature-independent ρxx. This observation is explained by a transition from a spin polarized ν=0 QHS at small E-fields, to a valley (layer) polarized ν=0 QHS at large E-fields. The E-field value at which the transition occurs has a linear dependence on B
@article{arxiv.1102.0265,
title = {Spin-Polarized to Valley-Polarized Transition in Graphene Bilayers at $\nu=0$ in High Magnetic Fields},
author = {Seyoung Kim and Kayoung Lee and Emanuel Tutuc},
journal= {arXiv preprint arXiv:1102.0265},
year = {2011}
}