  Quantum Hall effects offer a formidable playground for the investigation of
quantum transport phenomena. Edge modes can be detected, branched, and mixed by
designing a suitable potential landscape in a two-dimensional conducting system
subject to a strong magnetic field. In the present work, we demonstrate a
buried split-gate architecture and use it to control electron conduction in
large-scale single-crystal monolayer graphene grown by chemical vapor
deposition. The control of the edge trajectories is demonstrated by the
observation of various fractional quantum resistances, as a result of a
controllable inter-edge scattering. Experimental data are successfully modeled
both numerically and within the Landauer-Buettiker formalism. Our architecture
is particularly promising and unique in view of the investigation of quantum
transport via scanning probe microscopy, since graphene constitutes the topmost
layer of the device. For this reason, it can be approached and perturbed by a
scanning probe down to the limit of mechanical contact.
