Manipulating electron reservoirs in bilayer electron systems

We present experimental results on electron transport in a bilayer electron system that consists of two uncoupled two-dimensional electron gases (2DEGs) formed in a double quantum well within a GaAs/AlGaAs heterostructure. Our measurements of the capacitance between the top gate and the 2DEGs as a function of varying magnetic fields at total integer filling factors reveal critical insights into the net interlayer charge transfer required for the layers to maintain equal electrochemical potentials. In instances where both layers operate in the quantum Hall effect regime, the magnetocapacitance demonstrates anticoercive hysteresis. In particular, the change in electron density linked to this hysteresis significantly surpasses that associated with equilibrium interlayer charge transfer, indicating that hysteresis and interlayer charge transfer arise from distinct phenomena. Furthermore, at high amplitudes of the alternating gate voltage, we observe a nonlinear change in magnetocapacitance, indicating a breakdown of the quantum Hall effect.