ELECTRON CORRELATION AND CHARGE-TRANSFER INSTABILITY IN BILAYERED 2-DIMENSIONAL ELECTRON-GAS

We prove that the predicted charge transfer state in symmetric bilayer s of two-dimensional electron gases is always unstable at zero bias vo ltage, due to interlayer interactions and/or tunneling. This is most e asily seen by resorting to a pseudospin formalism and considering cohe rent states obtained from the charge transfer state through rotations of the pseudospins. Evidently, the charge transfer state is stabilized by a sufficiently strong gate voltage, as found in recent experiments . We show that a simple model, in which the layers are strictly two-di mensional, is able to account quantitatively for such experimental fin dings, when correlation is properly included.