Fractional quantum Hall effect in bilayer two-dimensional hole-gas systems.

We have studied the fractional and integer quantum Hall effect in high-mobility double-layer two-dimensional hole-gas systems. The large hole effective mass inhibits tunneling, allowing us to investigate the regime in which the interlayer and intralayer interactions are comparable without significant interlayer tunneling occurring. As the interlayer separation is reduced we observe the formation of bilayer-correlated quantum Hall states at total filling factor $\ensuremath{\nu}=\frac{3}{2}$ and $\ensuremath{\nu}=1$. We find that the bilayer $\ensuremath{\nu}=\frac{3}{2}$ state is rapidly destroyed by small carrier density imbalances between the layers, whereas the bilayer $\ensuremath{\nu}=1$ state evolves continuously into the single-layer $\ensuremath{\nu}=1$ state.