Regensburg 2022 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 10: Poster Session 1

MM 10.12: Poster

Monday, September 5, 2022, 18:00–20:00, P2

Flatbands and Nonlinear Transport in Nodal Line Semimetals — •Thomas Bömerich, Jinhong Park, and Achim Rosch — Institute for Theoretical Physics, University of Cologne, Germany

Ohm’s law describes the linear dependence of the current on the electric field. Although deviations from this relation are quite small for usual metals we present a model of a semimetal with large non-ohmic conductivity. Motivated by recent experiments on ZrTe₅ we study a low-energy Hamiltonian consisting of a single Dirac point which gets deformed into a nodal line by mirror symmetry breaking. Upon Landau quantization a zero energy state for a wide range of momenta emerges. For small densities the lowest Landau level can be reached at feasible magnetic fields making it possible to investigate the properties of the flatband.

While flatbands have generated growing interest because of their large density of states and the importance of interactions, we instead focus on their impact on nonlinear transport. Using the Boltzmann equation we obtain higher order conductivities and compare our results to a Dirac semimetal. We show that in the quantum limit, the nonlinear signal of the nodal line semimetal is five orders of magnitude larger than the Dirac semimetal. This enhancement of the nonlinear properties orginates from the emergence of the flat bands in the nodal line semimetal. Additionally we investigate the influence of disorder on the linear conductivity.