Magnetotransport and interlayer-edge channel tunneling of two-dimensional electrons in a double-quantum-well system

In-plane magnetotransport of resonantly coupled two-dimensional electron gases (2DEG's) has been systematically studied in a $\mathrm{GaAs}/{\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ double-quantum-well system in which the top 2DEG is disconnected from all the Ohmic contacts to probe the bottom 2DEG selectively. When the filling factor is an integer, the tunneling between two 2DEG's is found to be substantially suppressed, resulting in the sudden and twofold increase of the Hall resistance. It is also found that the minima of the magnetoresistance do not vanish, indicating the importance of tunnel interaction between nonequilibrium edge channels of two quantum-well layers.