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arXiv:1506.05706 · Journal of Magnetism and Magnetic Materials

Dynamical vertex approximation for the two-dimensional Hubbard model

Thomas Schäfer, A. Toschi, Karsten Held

Published Jul 30, 2015• 40 citations
arXivHTMLPDF
DOI
10.1016/j.jmmm.2015.07.103

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We have studied the impact of nonlocal electronic correlations at all length scales on the Mott-Hubbard metal-insulator transition in the unfrustrated two-dimensional Hubbard model. Combining dynamical vertex approximation, lattice quantum Monte Carlo, and variational cluster approximation, we demonstrate that scattering at long-range fluctuations, i.e., Slater-like paramagnons, opens a spectral gap at weak-to-intermediate coupling, irrespective of the preformation of localized or short-range magnetic moments. This is the reason why the two-dimensional Hubbard model has a paramagnetic phase which is insulating at low enough temperatures for any (finite) interaction and no Mott-Hubbard transition is observed.