Progress towards probing quantum Hall edge states in Graphene Heterostructures

Capacitance measurements reveal graphite gated, hexagonal boron nitride encapsulated graphene to be an extremely clean two dimensional electron system. In these devices, well-developed incompressible fractional quantum Hall peaks are evident down to magnetic fields as small as 1 Tesla, with a variety of even denominator fractional quantum hall states appearing at high magnetic fields. However, these states appear less accessible in multiterminal transport measurements due to fringe field effects, etch-induced edge disorder, contact resistances and other unknown issues. This makes mesoscopic physics experiments that rely on edge properties--such as edge state interferometry--an experimental challenge. I will give a progress report on our efforts to probe edge states with transport measurements, including efforts to engineer all-electrostatically defined devices.