Anomalous high-field magnetotransport in CaFeAsF due to the quantum Hall effect

CaFeAsF is an iron-based superconductor parent compound whose Fermi surface is quasi-two dimensional, composed of Dirac-electron and Schrodinger-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 similar to 40 T as the temperature was lowered to 0.4 K. Our analysis indicates that the Landau-level filling factor is nu = 2 for both electrons and holes at these high field strengths, resulting in a total filling factor nu = nu(hole) - nu(electron) = 0. We therefore argue that the nu = 0 quantum Hall state emerges under these conditions.

Automated summary

In this study, the resistivity and conductivity were measured in CaFeAsF, and the emergence of the nu = 0 quantum Hall state was observed under high magnetic field strengths.