Area dependence of interlayer tunneling in strongly correlated bilayer 2D electron systems at ν_T=1

The area and perimeter dependence of the Josephson-like interlayer tunneling signature of the coherent $\nu_T=1$ quantum Hall phase in bilayer two-dimensional electron systems is examined. Electrostatic top gates of various sizes and shapes are used to locally define distinct $\nu_T=1$ regions in the same sample. Near the phase boundary with the incoherent $\nu_T=1$ state at large layer separation, our results demonstrate that the tunneling conductance in the coherent phase is closely proportional to the total area of the tunneling region. This implies that tunneling at $\nu_T=1$ is a bulk phenomenon in this regime.