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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 Hubbardmodel is introduced, describing vacancy-interstitial pair excitations withinthe Wigner crystal. Kinetic energy gained by delocalizing such excitations isfound to lead to an instability of the insulator to self-doping above acritical carrier concentration $n=n c$, mapping the problem to a density-drivenMott MIT. This mechanism provides a natural microscopic picture of severalpuzzling experimental features, including the large effective mass enhancement,the large resistivity drop, and the large positive magneto-resistance on themetallic side of the transition. We also present a global phase diagram for theclean 2D electron gas as a function of $n$ and parallel magnetic field$B {\shortparallel}$, which agrees well with experimental findings in ultraclean samples.



Autor: S. Pankov, V. Dobrosavljevic

Fuente: https://arxiv.org/







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