Fermi surface with Dirac fermions in CaFeAsF determined via quantum oscillation measurements

Abstract

Despite the fact that 1111-type iron arsenides hold the record transition temperature of iron-based superconductors, their electronic structures have not been studied much because of the lack of high-quality single crystals. In this study, we completely determine the Fermi surface in the antiferromagnetic state of CaFeAsF, a 1111 iron-arsenide parent compound, by performing quantum oscillation measurements and band-structure calculations. The determined Fermi surface consists of a symmetry-related pair of Dirac electron cylinders and a normal hole cylinder. From analyses of quantum-oscillation phases, we demonstrate that the electron cylinders carry a nontrivial Berry phase $\pi$. The carrier density is of the order of 10${}^{-3}$ per Fe. This unusual metallic state with the extremely small carrier density is a consequence of the previously discussed topological feature of the band structure which prevents the antiferromagnetic gap from being a full gap. We also report a nearly linear-in-$B$ magnetoresistance and an anomalous resistivity increase above about 30 T for $B\parallel c$, the latter of which is likely related to the quantum limit of the electron orbit. Intriguingly, the electrical resistivity exhibits a nonmetallic temperature dependence in the paramagnetic tetragonal phase ($T>$ 118 K), which may suggest an incoherent state. Our study provides a detailed knowledge of the Fermi surface in the antiferromagnetic state of 1111 parent compounds and moreover opens up a new possibility to explore Dirac-fermion physics in those compounds.

11 pages, 7 figures, 1 table

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Cited by in corpus (17)

• Bulk Fermi surfaces of the Dirac type-II semimetallic candidate NiTe2
• Elastoresistance measurements on CaKFe${}_4$As${}_4$ and KCa${}_2$Fe${}_4$As${}_4$F${}_2$ with the Fe site of $C_{2v}$ symmetry
• Simple mechanisms that impede the Berry phase identification from magneto-oscillations
• Optical study of Dirac fermions and related phonon anomalies in antiferromagnetic compound CaFeAsF
• Real spin and pseudospin topologies in the noncentrosymmetric topological nodal-line semimetal CaAgAs
• First-principles methodology for studying magnetotransport in narrow-gap semiconductors: an application to Zirconium Pentatelluride ZrTe5
• Coherent heavy charge carriers in an organic conductor near the bandwidth-controlled Mott transition
• Two-Gap Superconductivity in CaFe_{0.88}Co_{0.12}AsF Revealed by Temperature Dependence of the Lower Critical Field H_{c1}^c(T)
• Topological frequency shift of quantum oscillation in CaFeAsF
• Large CaFeAsF single crystals of high quality grown by the oscillating temperature technique
• Three-dimensional quantum Griffiths singularity in bulk iron-pnictide superconductors
• Anomalous High-Field Magnetotransport in CaFeAsF due to the Quantum Hall Effect
• Linear scaling relation between two-dimensional massless Dirac fermion Fermi velocity and Fe-As bond length in iron arsenide superconductor systems
• Multiple gaps revealed by low temperature specific heat in the 1111-type CaFe_{0.88}Co_{0.12}AsF single crystals
• In-plane electronic anisotropy revealed by interlayer resistivity measurements on the iron-based superconductor parent compound CaFeAsF
• Magnetotransport studies of optimally doped Sr(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$
• Observation of the Dirac Dispersions in Co-doped CaFe2As2