arXiv, 2021
DOI: 10.48550/arxiv.2107.10460
Nature Research, npj Quantum Materials, 1(7), 2022
DOI: 10.1038/s41535-022-00470-6
AbstractCaFeAsF is an iron-based superconductor parent compound whose Fermi surface is quasi-two dimensional, composed of Dirac-electron and Schrödinger-hole cylinders elongated along the c axis. We measured the longitudinal and Hall resistivities in CaFeAsF with the electrical current in the ab plane in magnetic fields up to 45 T applied along the c axis and obtained the corresponding conductivities via tensor inversion. We found that both the longitudinal and Hall conductivities approached zero above ~40 T as the temperature was lowered to 0.4 K. Our analysis indicates that the Landau-level filling factor is ν = 2 for both electrons and holes at these high field strengths, resulting in a total filling factor ν = νhole − νelectron = 0. We therefore argue that the ν = 0 quantum Hall state emerges under these conditions.