Study of Correlated Insulators and Metals in Two Dimensions

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This project will address simultaneously two major problems of condensed matter physics: The metal-insulator transition and glassy behavior. Recent studies have indicated that the two are most likely intimately related. The focus of this experimental project will be on the properties of two-dimensional systems in semiconductor heterostructures. Specific topics to be addressed using a two-dimensional electron system in Si include: (1) nonequilibrium glassy dynamics, (2) the role of the range of Coulomb interactions on the metal-insulator transition and glassy effects, and (3) the effect of local magnetic moments on the metal-insulator transition and glassy behavior. In addition, the possibility of glassy freezing in two-dimensional systems in other materials will be also explored. These issues will be investigated using a combination of transport and noise measurements. The results should provide information on crucial aspects of the problem: disorder, electron-electron interactions, and the role of spin and charge degrees of freedom. This will contribute significantly to our understanding of disordered, strongly correlated systems. In pursuing these objectives, undergraduate students, graduate students and postdocs will acquire valuable technical and analytical skills for a wide range of careers in the areas of science and technology in academic, industrial or government settings.In many of the novel materials with potentially great technological importance, such as recently discovered high temperature superconductors, the metallic state is created by chemically doping an otherwise insulating material. Such materials, therefore, find themselves close to a so-called "metal-insulator" transition. Understanding the nature of the metal-insulator transition thus represents an important issue for the materials science and technology. It also presents a fundamental problem in condensed matter physics. Several recent studies have shown striking similarities in the behavior of systems close to a metal-insulator transition and those of various glassy materials, the understanding of which also presents one of the deepest and most interesting problems in physics. This experimental condensed matter physics project will address simultaneously both the problem of the metal-insulator transition and that of glassy behavior by using a combination of electrical transport and noise measurements. The results anticipated from these experiments are expected to provide a fundamental insight into these problems. Furthermore, since measurements will be carried out on semiconductor heterostructures, the results may have an impact on the development of next generation semiconductor devices to be used in new technological areas such as quantum computation and spintronics, for example, where device noise may be one of the main factors limiting its performance. The project will give postdoctoral researchers, graduate and undergraduate students an excellent preparation for careers in academia, industry, and government.