Speaker
Description
Following nearly a century of research, it remains a puzzle that the low-lying excitations of metals are remarkably well explained by effective single-particle theories of non-interacting bands even though mutually interacting electronic states are a property of essentially all materials. This raises the question of direct spectroscopic signatures of phenomena beyond effective single-particle, single-band behaviour. Here we report the identification of quantum oscillations (QOs) of the quasi-particle (QP) lifetime, which defy the standard description in two fundamental aspects. First, the oscillation frequency corresponds to the difference of semi-classical QP orbits of two bands, which are forbidden as half of the trajectory would oppose the Lorentz force. Second, the oscillations persist to much higher temperatures compared to the basis frequencies. The only precondition for their existence is a non-linear coupling of at least two electronic orbits, e.g., due to QP scattering on defects or collective excitations. Such QOs of the QP lifetime are generic for any metal featuring Landau quantization with multiple orbits. We show that the underlying notion of QOs without corresponding Fermi surface cross-sections is in excellent agreement with the three-dimensional topological semimetal CoSi, as well as several other topological semimetals. It offers also an unexpected new perspective on Fe-based superconductors, where a spontaneous emerging QO frequency across the nematic transition has up to now been understood as a Lifshitz transition. We discuss the general relevance of our finding for interpreting QO data in terms of the correct underlying electronic structure.
Huber, Leeb, Bauer, Benka, Knolle, Pfleiderer, Wilde. 2023, [forthcoming]
Leeb, Knolle. 2023, [forthcoming]
Leeb, Knolle. 2023, [forthcoming]
