This is a condensed matter physics experimental project aimed at improving our understanding of the collective behavior of two-dimensional electron systems in advanced semiconductor heterostructures. Attention will be focused on electrical transport, quantum tunneling, and Coulomb drag measurements at high magnetic field and very low temperature. These probes will be applied to the newly discovered many-electron states in highly excited Landau levels and to the remarkable ferromagnetic configurations that two-dimensional electrons in double layer systems exhibit. The results of these experiments will help to elucidate the underlying structure (e.g. correlated liquid, charge density wave, etc.) of these unusual phases of matter. As the quantum many-body problem is at the heart of modern condensed matter physics, the planned research will have broad significance. A positive impact on the materials science of advanced crystal growth can also be expected since only the very purest semiconductor samples are suitable for this research. The research provides excellent educational opportunities for graduate students and post-doctoral associates who be trained for careers in academe, industry or government. Their work involves fundamental physics and exposure to cutting edge materials and instrumentation. %%% This experimental condensed matter physics project is aimed at improving the basic understanding of how large groups of electrons behave in technologically important semiconductor materials. The planned research will have several outcomes: First, the fundamental properties of the electron systems themselves will be elucidated. Attention will be focussed on those aspects that depend critically on the repulsive forces the electrons exert upon one another. This "many-body problem" is at the core of modern condensed matter science. Second, this research will advance the frontiers of materials science. The samples needed for this work require the most advanced methods of crystal growth for their fabrication and, in the end, must be of the very highest purity and complexity. These same growth methods are used to fabricate a wide variety of technologically important devices, ranging from fast transistors for cellular telephones to lasers for compact disk players. This research has a strong educational component and will contribute to the Nation's technological competitiveness.
