Electron Correlation and Charge Transfer Instability in Bilayered Two Dimensional Electron Gas

TL;DR

This paper demonstrates that charge transfer states in symmetric bilayer two-dimensional electron gases are inherently unstable at zero bias due to interlayer interactions, but can be stabilized by an external gate voltage, with a simple model accurately matching experimental data.

Contribution

It introduces a pseudospin formalism to analyze charge transfer instability and shows how correlation effects and gate voltage influence stability in bilayer electron gases.

Findings

Charge transfer state is unstable at zero bias due to interlayer effects.

A simple two-dimensional model with correlation explains experimental stabilization.

Gate voltage can stabilize charge transfer states in bilayer systems.

Abstract

We prove that the predicted charge transfer state in symmetric bilayers of two dimensional electron gases is always unstable at zero bias voltage, due to interlayer correlation and/or tunneling. This is most easily seen by resorting to a pseudospin formalism and considering coherent 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 dimensional, is able to account quantitatively for such experimental findings, when correlation is properly included.