By using four-terminal configurations, we investigated the dependence of longitudinal and diagonal resistances of a graphene $p\text{−}n$ interface on the quantum-Hall edge-state equilibration position. The resistance of a $p\text{−}n$ device in our four-terminal scheme is asymmetric with respect to the zero point where the filling factor $\left(\nu \right)$ of the entire graphene vanishes. This resistance asymmetry is caused by the chiral direction dependent change in the equilibration position and leads to a deeper insight into the equilibration process of the quantum-Hall edge-states in a bipolar graphene system.

• Received 5 October 2009

DOI:https://doi.org/10.1103/PhysRevB.81.033301