We present a theory describing the mechanism for the two-dimensional (2D) metal-insulator transition (MIT) in absence of disorder. A two-band Hubbard model is introduced, describing vacancy-interstitial pair excitations within the Wigner crystal. Kinetic energy gained by delocalizing such excitations is found to lead to an instability of the insulator to self-doping above a critical carrier concentration n=nc, mapping the problem to a density-driven Mott MIT. This mechanism provides a natural microscopic picture of several puzzling experimental features, including the large effective mass enhancement, the large resistivity drop, and the large positive magneto-resistance on the metallic side of the transition. We also present a global phase diagram for the clean 2D electron gas as a function of n and parallel magnetic field B∥, which agrees well with experimental findings in ultra clean samples.
@article{arxiv.0705.3428,
title = {Self-doping instability of the Wigner-Mott insulator},
author = {S. Pankov and V. Dobrosavljevic},
journal= {arXiv preprint arXiv:0705.3428},
year = {2008}
}