V = 1 BILAYER QUANTUM HALL STATE AT ARBITRARY ELECTRON-DISTRIBUTION IN A DOUBLE-QUANTUM-WELL

We demonstrate unique characteristics of the correlated v = 1 bilayer quantum Hall state in a GaAs/AlGaAs double quantum well. By controllin g the total electron density as well as the distribution of electrons in the wells, we measured the magnetoresistance and the Hail resistanc e especially at around v = 1. The plateau width of the v = 1 quantum H all state is used to estimate the stability of the stale and found to be sensitive only to the total electron density, and almost independen t of the ratio of electrons between two layers. These experimental dat a can be interpreted as the existence of incompressible bilayer v = 1 quantum Hall state at any ratio. The impact of the findings on the pos sibility of observing interlayer quantum coherence, which is theoretic ally predicted, is also discussed. (C) 1998 Published by Elsevier Scie nce Ltd. All rights reserved.