Berlin 2024 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 9: Focus Session: Anomalous Quantum Oscillations
TT 9.1: Hauptvortrag
Montag, 18. März 2024, 15:00–15:30, H 0104
Unusual Magnetic Oscillations in Kagome Mott Insulators — •Lu Li — University of Michigan, Ann Arbor, MI 48109, US
The observations of the Landau Level quantizations in narrow-gapped correlated Kondo insulators raise intriguing questions on the origins [1]. However, none of the models suggest the phenomena existing in wide-gap insulators. Kagome lattice Mott insulator Herbertsmithite is a well-established Dirac fermion spin liquid candidate. Yet, our search for magnetic oscillations in Herbertsmithite yielded only a series of magnetic transitions [2], possibly due to the ion disorders on the Kagome lattice. This problem is resolved in the recently discovered sibling compound YCu3(OH)6.5Br2.5 [3]. Using ultrasensitive magnetometry in 70 T intense fields, we observe both the 1/3-plateau and 1/9-plateau transitions. The magnetometry reveals strong oscillations in the magnetic torque. While the temperature dependence follows the Fermi liquid theory, the oscillations appear to be roughly periodic in the magnetic field B, opposite to the 1/B trend in conventional metals. Furthermore, a strong angular dependence is observed for the oscillation fields, which indicates the orbital effect. Separating orbital and Zeeman effect, we show that this magnetic oscillation pattern is consistent with a Dirac fermion existing near the 1/9 plateau, and the fermion’s chemical potential is shifted by the Zeeman effect [4].
[1] Xiang, Li et al., Science 362, 65 (2018); Li et al., Nat. Rev. Phys. 2, 463 (2020); Xiang, Li et al., Nat. Phys. 17, 788 (2021).
[2] Asaba, Li et al., Phys. Rev. B 90, 064417(2014)
[3] Zeng et al., PRB 105, L121109 (2022)
[4] Zheng et al., arXiv:2310.07989 (2023)