The hysteresis observed in the magnetoresistance of bilayer 2D systems in the quantum Hall regime is generally attributed to the long time constant for charge transfer between the 2D systems due to the very low conductivity of the quantum Hall bulk s
tates. We report electrometry measurements of a bilayer 2D system that demonstrate that the hysteresis is instead due to non-equilibrium induced current. This finding is consistent with magnetometry and electrometry measurements of single 2D systems, and has important ramifications for understanding hysteresis in bilayer 2D systems.
We discuss the development of a sensitive electrometer that utilizes a two-dimensional electron gas (2DEG) in the quantum Hall regime. As a demonstration, we measure the evolution of the Landau levels in a second, nearby 2DEG as the applied perpendic
ular magnetic field is changed, and extract an effective mass for electrons in GaAs that agrees within experimental error with previous measurements.
The use of a nearby metallic ground-plane to limit the range of the Coulomb interactions between carriers is a useful approach in studying the physics of two-dimensional (2D) systems. This approach has been used to study Wigner crystallization of ele
ctrons on the surface of liquid helium, and most recently, the insulating and metallic states of semiconductor-based two-dimensional systems. In this paper, we perform calculations of the screening effect of one 2D system on another and show that a 2D system is at least as effective as a metal in screening Coulomb interactions. We also show that the recent observation of the reduced effect of the ground-plane when the 2D system is in the metallic regime is due to intralayer screening.
We have developed a technique utilizing a double quantum well heterostructure that allows us to study the effect of a nearby ground-plane on the metallic behavior in a GaAs two-dimensional hole system (2DHS) in a single sample and measurement cool-do
wn, thereby maintaining a constant disorder potential. In contrast to recent measurements of the effect of ground-plane screening of the long-range Coulomb interaction in the insulating regime, we find surprisingly little effect on the metallic behavior when we change the distance between the 2DHS and the nearby ground-plane.
