Topological frequency shift of quantum oscillation in CaFeAsF

Abstract

Guo, Alexandradinata, \textit{et al.} have recently proposed that quantum-oscillation frequencies from Dirac/Weyl fermions exhibit a negative shift proportional to $T^2$ because of the energy dependence of the effective mass peculiar to a linear band-dispersion. We have measured Shubnikov--de Haas oscillation in CaFeAsF up to $T$ = 9 K. The frequency of the $\alpha$ Dirac electron exhibits a negative shift with increasing $T$, while that of the $\beta$ Schrödinger hole does not. For $T⩾5$ K where $\beta$ is negligible, the $\alpha$-frequency shift is proportional to $T^2$ and its rate agrees with the theoretical prediction within experimental accuracy. At lower temperatures, the shifts of $\alpha$ and $\beta$ deviate from theoretical expectations, which we ascribe to the inaccuracy in the frequency determination due to unfavorable interference between frequencies. Our results confirm that the topological frequency shift can be utilized to identify Dirac/Weyl fermions when quantum-oscillation frequencies can be determined accurately.

Minor revision after publication, ref. 16 updated (found already published), 16 pages, 4 figures, 1 table

References in corpus (4)

• Quantum oscillations and the Fermi surface in an underdoped high-Tc superconductor
• Topological origin of subgap conductance in insulating bilayer graphene
• Two-dimensional Dirac fermions in a topological insulator: transport in the quantum limit
• Growth and Characterization of Millimeter-sized Single Crystals of CaFeAsF

Cited by in corpus (3)

• In-plane electronic anisotropy revealed by interlayer resistivity measurements on the iron-based superconductor parent compound CaFeAsF
• Anomalous High-Field Magnetotransport in CaFeAsF due to the Quantum Hall Effect
• Superconductivity above 30 K due to the introduction of oxygen in CaFeAsF