Zero-Energy State in Graphene in a High Magnetic Field

Joseph G. Checkelsky, Lu Li, N. P. Ong
2008 Physical Review Letters  
The fate of the charge-neutral Dirac point in graphene in a high magnetic field $H$ has been investigated at low temperatures ($T\sim$ 0.3 K). In samples with small $V_0$ (the gate voltage needed to access the Dirac point), the resistance $R_0$ at the Dirac point diverges steeply with $H$, signalling a crossover to an insulating state in intense field. The approach to the insulating state is highly unusual. Despite the steep divergence in $R_0$, the profile of $R_0$ vs. $T$ in fixed $H$
more » ... n fixed $H$ saturates to a $T$-independent value below 2 K, consistent with charge carrying gapless excitations.
doi:10.1103/physrevlett.100.206801 pmid:18518564 fatcat:xmsomu7tx5edxgkouf3s32bicu