Project Details
Projekt
Modeling non-local interaction phenomena in real materials: electrons, lattice and topology
Applicants
Professor Dr. Dmitri K. Efetov; Professor Dr. Giorgio Sangiovanni; Professor Dr. Tim Wehling
Subject Area
Theoretical Condensed Matter Physics
Experimental Condensed Matter Physics
Experimental Condensed Matter Physics
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 449872909
The interplay of phonons, electron correlations, and topology is an outstanding challenge in condensed matter physics. It determines phase diagrams, transport properties, and the response of quantum phases to external stimuli. Very often, however, there is no clear link between simple models and the physics taking place in actual materials, and the complexity of quantum materials evades a clear understanding, let alone a theory-guided optimization of their functional properties. The theme of P5 is to facilitate a quantitative understanding and modeling of quantum materials featuring an interplay of phonons, electron correlations, and topology. With the exemplary platforms of topological heavy fermions (THF) in twisted moiré materials, of kagome metals and TaS2, we aim to understand how this interplay influences the emergence of phases, including charge ordered, time-reversal broken and superconducting states, how it affects phase-coexistence and metastability, and how it controls the coupling to strain and to electromagnetic fields. We aim at explaining the impact of phonons, correlations, and topology on electronic excitations, collective modes, and transport properties including the enigmatic strange-metallicity seen in correlated electron systems. Having a pioneer in graphene moiré experiments, Dmitri Efetov, joining P5 as a new PI enables a unique synergy between theory and experiment, bridging the gap between theoretical modeling and the rapidly advancing experimental characterization of transport properties. Addressing transport in correlated systems remains a major challenge, as the accuracy of current-current response functions does not yet measure up to that of single-particle spectral functions, the natural output of most Green function-based many-body approaches. Efetov's group will provide direct experimental access to both electronic spectra and transport measurements, allowing us to implement a unique double handshake approach connecting theoretical predictions and experiments on both kinds of observables. We will closely collaborate with our QUAST partners, to investigate topology in many-electron systems, explore electron-phonon-induced metastability and dynamics, and study non-local correlations and electron-phonon interaction effects using diagrammatic extensions of the dynamical mean-field theory (DMFT). Transport phenomena in topological systems will be addressed with theoretical developments of real-frequency impurity solvers on low-temperature magnetotransport experiments. Methodologically, we will advance the ab initio model-building of electron-phonon-coupled correlated quantum matter, bring phase-space-extension methods for metastable states in DMFT to a next level, advance the modeling of charge- and current-response functions as well as electron-phonon vertices, include dispersive phonons, and address spatial correlation effects through diagrammatic extensions of DMFT as well as slave- rotor approaches.
DFG Programme
Research Units
