Author: ["A. Camjayi","K. Haule","V. Dobrosavljević","G. Kotliar"]
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Abstract
Evidence for metal–insulator transitions in dilute 2D electron gases has sparked controversy and debate. A new model suggests such behaviour could arise from strong correlations driven by non-local Coulomb interactions, providing an alternative view to that which considers disorder to be the over-riding influence. Strong correlation effects, such as a marked increase in the effective mass of the carriers of electricity, recently observed in the low-density electron gas1 have provided spectacular support for the existence of a sharp metal–insulator transition in dilute two-dimensional electron gases2. Here, we show that strong correlations, normally expected only for narrow integer-filled bands, can be effectively enhanced even far away from integer-filling, owing to incipient charge ordering driven by non-local Coulomb interactions. This general mechanism is illustrated by solving an extended Hubbard model using dynamical mean-field theory3. Our findings account for the key aspects of the experimental phase diagram, and reconcile the early viewpoints of Wigner and Mott. The interplay of short-range charge order and local correlations should result in a three-peak structure in the electron spectral function, which can be observed in tunnelling and optical spectroscopy. These experiments will discriminate between the Wigner–Mott scenario and the alternative perspective that views disorder as the main driving force for the two-dimensional metal–insulator transition4.Cite this article
Camjayi, A., Haule, K., Dobrosavljević, V. et al. Coulomb correlations and the Wigner–Mott transition. Nature Phys 4, 932–935 (2008). https://doi.org/10.1038/nphys1106 