Non-Fermi liquid transport in the vicinity of the nematic quantum critical point of superconducting FeSe_{1−x}S_{x}

Abstract

Non-Fermi liquids are strange metals whose physical properties deviate qualitatively from those of conventional metals due to strong quantum fluctuations. In this paper, we report transport measurements on the FeSe_{1−x}S_{x} superconductor, which has a quantum critical point of a nematic order without accompanying antiferromagnetism. We find that in addition to a linear-in-temperature resistivity ρ_{xx}∝T, which is close to the Planckian limit, the Hall angle varies as cotθ_{H}∝T^{2} and the low-field magnetoresistance is well scaled as Δρ_{xx}/ρ_{xx}∝tan^{2}θ_{H} in the vicinity of the nematic quantum critical point. This set of anomalous charge transport properties show striking resemblance with those reported in cuprate, iron-pnictide, and heavy fermion superconductors, demonstrating that the critical fluctuations of a nematic order with q≈0 can also lead to a breakdown of the Fermi liquid description.