Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 10: Topological Semimetals
TT 10.5: Talk
Monday, March 17, 2025, 16:00–16:15, H36
Quantum geometry of topological nodal planes in Kondo systems — •Yannis Ulrich1, Andreas Schnyder1, and Laura Classen1,2 — 1Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany — 2Department of Physics, Technical University of Munich, D-85748 Garching, Germany
The geometric properties of the Hilbert space of Bloch states, such as the Berry curvature or quantum metric, play an important role in understanding topological semimetals. They are also fundamental for the understanding of various physical responses, including the (non-)linear Hall effect and (magneto-)optical conductivities. In this talk, I investigate the quantum geometry of two-dimensional topological band degeneracies, i.e., topological nodal planes, with a flat dispersion. Such nodal planes naturally arise in Kondo materials with screw rotation symmetries. Using a periodic Anderson model, I show how nodal planes in these Kondo materials can be tuned via pressure or temperature to be close to the Fermi level with a nearly flat dispersion. I show that such flat nodal planes exhibit a substantial quantum geometry, which in turn leads to nontrivial signatures in the (non-)linear Hall responses. Derivations of the Hall conductivities are presented in the manifestly gauge-invariant language of projectors, emphasizing their advantages in this type of calculation.
Keywords: Quantum geometry; Hall effect; Nodal planes; Kondo materials; Flat bands