# SKM 2023 – wissenschaftliches Programm

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# TT: Fachverband Tiefe Temperaturen

## TT 43: Poster: Correlated Electrons II

### TT 43.27: Poster

### Mittwoch, 29. März 2023, 15:00–18:00, P2/OG3

**Quantum oscillations beyond the Onsager relation in a doped Mott insulator** — •Valentin Leeb^{1,2} and Johannes Knolle^{1,2,3} — ^{1}Technical University of Munich, Germany; TUM School of Natural Sciences, Department of Physics, TQM — ^{2}Munich Center for Quantum Science and Technology (MCQST), 80799 Munich, Germany — ^{3}Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom

The kinetic energy of electrons in a magnetic field is quenched resulting in a discrete set of highly degenerate Landau levels (LL). This gives rise to fascinating phenomena like quantum oscillations or the integer and fractional quantum Hall effect. The latter is a result of interactions partially lifting the degeneracy within a given LL while inter-LL interactions are usually assumed to be unimportant. Here, we study the LL spectrum of the Hatsugai--Kohmoto model, a Hubbard-like model which is exactly soluble on account of infinite range interactions. For the doped Mott insulator phase in a magnetic field we find that the degeneracy of LLs is preserved but inter-LL interactions are important leading to a non-monotonous reconstruction of the spectrum. As a result, strong interactions lead to aperiodic quantum oscillations of the metallic phase in contrast to Onsager's famous relation connecting oscillation frequencies with the Fermi surface areas at zero field. In addition, we find unconventional temperature dependencies of quantum oscillations and effective mass renormalizations. We discuss the general importance of inter-LL interactions for understanding doped Mott insulators in magnetic fields.