Transport and Tunneling Studies of Electronic Materials at Quantum Critical Points

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This individual investigator award will fund a project with a goal of understanding the nature of electrical transport in systems of one, two or three dimensions in the vicinity of the metal-insulator transition (MIT). It is believed that in this regime, the behavior reflects a zero temperature quantum critical point that separates the metal from the insulator. On both sides of this point, the behavior is believed to be reflective of quantum mechanical ground states but the extent to which this is understood is minimal. In part this is because the traditional description of a metal in terms of a Landau liquid is simply inadequate and the properties are dominated by coulomb correlations. This investigator's laboratory has developed techniques to continuously "tune" through the MIT in all dimensions using a variety of methods...magnetic field tuning, continuous growth of films at low temperature, and adjustment of cross-sectional area of wires. Transport, electron tunneling and Hall effect measurements down to a temperature of 20 mK and up to magnetic fields of 20T will be used to build an experimental description of the transition and to test theoretical models. Graduate students will receive training both in condensed matter physics and technology. The physics issues are current and address the unknown aspects of electrical transport in reduced dimensions. The technology in materials and processing is state-of-the-art and will prepare them for a future career with a wide variety of options.This individual investigator award will fund work that addresses one of the most fundamental aspects of the electronic properties of materials...the metal insulator transition. This transition is at the apex of the differences between metals and insulators. Furthermore, as we will study the electrical transport in one, two and three dimensions, it not only addresses the dimensionality of this transition, the physics and materials issues that we learn will have practical importance. As wiring on integrated circuits and electronic memory gets smaller, it approaches these dimensionality limits. Graduate students will receive training both in condensed matter physics and technology. The physics issues are current and address the unknown aspects of electrical transport in reduced dimensions. The technology in materials and processing is state-of-the-art and will prepare them for a future career with a wide variety of options.