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arXiv · 0705.3428

Self-doping instability of the Wigner-Mott insulator

S. Pankov·V. Dobrosavljevic
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Abstract

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 $n=n_c$, 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 $B_{\shortparallel}$, which agrees well with experimental findings in ultra clean samples.

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S. Pankov, V. Dobrosavljevic. 2008-02-15. Self-doping instability of the Wigner-Mott insulator. https://doi.org/10.1103/physrevb.77.085104

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