This experimental research project focuses on conducting systems formed by the "edge states" that lie near the perimeter of quasi- two dimensional electron gases in the quantum Hall effect (QHE). Fundamentally new transport behavior is predicted for sample geometries that bring multiple edge states into communication. Two sample geometries will employed in this project. These are a GaAs/AlGaAs superlattice pillar with edge states communicating on a 2D surface sheath; and a gated GaAs/AlGaAs heterojunction with edge states communicating across a long, narrow "line gate" barrier. Existing theoretical predictions in these cases will be tested with measurements to be made using a high-field (19Tesla), low temperature (20mK) apparatus on samples fabricated from MBE- grown GaAs/AlGaAs heterostructures. It is expected that the results will advance general understanding of electronic transport in quasi-1D- and in anisotropic 3D- materials. %%% This experimental research project probes electron transport behavior in novel devices based on one of the most advanced device technologies in microelectronics; that based on the GaAs- GaAlAs system. This system is used in some advanced electron devices for computer use because it can lead to faster operation than equivalent devices made of silicon. The experiments will be based on thin conducting layers fabricated in the GaAlAs technology which give a confined two-dimensional "electron gas" in which the residual scattering from impurities and imperfections is reduced to extremely low levels, so that inherent electron gas behavior at very low temperatures and at high magnetic fields can be observed, and compared to recent theoretical models. Results from this research may include unusual new effects or materials which may find new application in tech nology. This research project is interdisciplinary in nature and involves graduate students who will be excellently trained to enter positions in industry, government or education. ***
