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TT: Fachverband Tiefe Temperaturen
TT 35: Focus Session: Correlations in Moiré Quantum Matter I
TT 35.5: Hauptvortrag
Mittwoch, 29. März 2023, 17:15–17:45, HSZ 03
Topology and strong correlation: From twisted bilayer graphene to the boundary zeros of Mott insulators — •Giorgio Sangiovanni1, Niklas Wagner1, Gautam Rai2, Lorenzo Crippa1, Tim Wehling2, and Roser Valentí3 — 1Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg — 2I. Institut für Theoretische Physik, Universität Hamburg — 3Institut für Theoretische Physik, Goethe-Universität Frankfurt am Main
Strong electronic correlations drive materials towards atomic-like Mott phases. How to topologically classify these many-body insulators is an open and highly debated question. In this talk I am going to start from twisted bilayer graphene, an example of the interplay between low-energy protection of single-particle eigenvalues and non-perturbative effects of electron-electron interactions. From this, I plan to move to a broader concept which has been spelled out in rather different ways in the recent literature: topological Mott insulators. Most of the proposed realizations rely either on Hartree-Fock approximations or on appropriately defined auxiliary degrees of freedom. I am going to present a novel, remarkably simple way of describing a topological Mott insulator without long-range order, based on the topological properties of their Green's function zeros in momentum space. After discussing the fate of the bulk-boundary correspondence in these systems, I will show how the zeros can be seen as a form of ``topological antimatter'' with distinctive features associated to the annihilation with conventional topologically protected edge modes.