At low temperatures and high magnetic fields, the exceptional mobility of
graphene allows for the observation of the quantum hall effect for both electrons and
holes (Fig. 3.4b)(Novoselov, Geim et al. 2005; Zhang, Tan et al. 2005). Due to its
unique band structure, the graphene quantum hall effect exhibits a subtle difference
from the conventional quantum Hall effect in that plateaus occur at half integers of
4e
2
/h rather than the typical 4e
2
/h.