Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: Focus Session: Anomalous Quantum Oscillations

TT 9.6: Talk

Monday, March 18, 2024, 17:45–18:00, H 0104

Interband scattering- and nematicity-induced quantum oscillation frequency in FeSe — •Valentin Leeb¹ and Johannes Knolle^1,2 — ¹Technical University of Munich, Germany — ²Imperial College London, United Kingdom

Understanding the nematic phase observed in the iron-chalcogenide materials is crucial for describing their superconducting pairing. Experiments on FeSe_1−xS_x showed that one of the slow Shubnikov–de Haas quantum oscillation frequencies disappears when tuning the material out of the nematic phase via chemical substitution or pressure, which has been interpreted as a Lifshitz transition [Coldea et al., npj Quant Mater 4, 2 (2019), Reiss et al., Nat. Phys. 16, 89-94 (2020)]. Here, we present a generic, alternative scenario for a nematicity-induced sharp quantum oscillation frequency which disappears in the tetragonal phase and is not connected to an underlying Fermi surface pocket. We show that different microscopic interband scattering mechanisms – for example, orbital-selective scattering – in conjunction with nematic order can give rise to this quantum oscillation frequency beyond the standard Onsager relation. We discuss implications for iron-chalcogenides and the interpretation of quantum oscillations in other correlated materials.

Keywords: Quantum Oscillations; Electronic nematic phase transition; superconductors; interband scattering