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Physics Seminar

Towards controlling quantum matter: Microscopic theory of correlated and complex electron systems

Speaker: Prof Tim Wehling (Bremen University)
Date: Wednesday 27 May 2020
Time: 15:00
Venue: Zoom

The interplay of electronic interactions, band structure, lattice degrees of freedom and nanostructuring forms a vital basis for controlling collective quantum phenomena. Here, we discuss how to model electronic correlation effects in atomic scale structured systems based on combinations of first-principles and many-electron techniques. We consider excitonic Mott transitions, superconductivity, and Mott-Hubbard metal insulator transitions in two-dimensional materials and analyze possibilities of “Coulomb engineering”, i.e controlling the electronic states via external screening. For the particular example of magic-angle twisted bilayer graphene (MA-tBLG), which features intricate superconducting, insulating and metallic many-electron states, we show that Coulomb engineering presents a promising tool for resolving the nature of the quantum many-body states realized in this system. We finally address the problem of how non-local interactions affect electronic correlations in Mott Hubbard systems, which are relevant e.g. in the context of high temperature superconductivity.