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Quantum Melting on a Lattice and Delocalization Transition


E.V. Tsiper


Dissertation

submitted to the faculty of the University of Utah
in partial fulfillment of the requirements for the degree of

Doctor of Philosophy

Abstract:
Quantum melting of a lattice Wigner crystal and the insulator-metal transition assosiated with it are studied using numerical techniques. It is shown that the lowest in energy excited state of the system plays crucial role in quantum melting. In a large enough system this state is a point defect in a Wigner crystal. Based on numerical data a simple picture of the transition is proposed. This picture leads to an empirical criterion that allows estimation of the critical point of the transition in various cases. It is shown that the picture provides a good description of the phase diagram of quantum melting in the one-dimensional (1D) model with the nearest- and the next-nearest interactions in the regions where the mixing of two competing crystals is not important. In the region of strong mixing an interesting metallic phase of a strongly interacting system is found.

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