Anisotropic superconductivity and high-pressure tuning of iron-iridium-arsenide Ca 10 (Ir 4 As 8 )(Fe 2− x Ir x As 2 ) 5

Abstract The 1048-type iron-based superconductors (IBSs) with metallic intermediary layers provide a valuable platform for examining how interlayer coupling, structural instabilities, and non-Fermi-liquid transport influence superconductivity. Here, we report the growth of high-quality single crystals of the 1048-type iron-iridium-arsenide Ca 10 (Ir 4 As 8 )(Fe 2− x Ir x As 2 ) 5 and a systematic study of its anisotropic superconducting and high-pressure transport properties. At ambient pressure, the material exhibits a structural transition near 100 K, a strange-metal normal state with nearly linear temperature-dependent resistivity, and bulk superconductivity with T c ∼ 16 K. Angular-dependent magneto-transport measurements analyzed within the anisotropic Ginzburg–Landau framework yield an upper critical field anisotropy γ ∼ 7–8 with weak temperature dependence near T c . Under modest pressure, both the structural transition and superconductivity are suppressed, while the low-pressure normal state retains non-Fermi-liquid behavior. With further compression, the transport evolves toward a Fermi-liquid regime without reemergence of superconductivity, demonstrating that pressure effectively tunes the electronic properties of this metallic-interlayer IBSs.