If a clean two-dimensional electron gas (2DEG) with a low concentration n comprises one electrode of a plane capacitor, the resulting capacitance C can be higher than the "geometric capacitance" Cg determined by the physical separation d between electrodes. A recent paper argued that when the effective Bohr radius aB of the 2DEG satisfies a Bâ‰d, one can achieve Câ‰Cg at a low concentration nd2â‰1. Here we show that even for devices with aB>d, including graphene, for which aB is effectively infinite, one also arrives at Câ‰Cg at low electron concentrations if there is a strong perpendicular magnetic field.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jan 9 2013|