High upper critical fields of superconducting Ca10(Pt4As8)(Fe1.8Pt0.2As2)5 whiskers

We investigated the upper critical fields of Ca10(Pt4As8)(Fe2–xPtxAs2)5 superconducting whiskers. The whiskers consist of several wire-like grains with diameter of around 200 nm, joined by grain boundaries whose misorientation angles are less than 5∘. The upper critical fields along c-axis and in ab-plane were observed as 49 T at 12 K and 50 T at 22 K, respectively, which can be extrapolated to ∼81 and ∼133 T at 0 K. The whisker demonstrated weak anisotropic factor and almost constant value of ∼2 below 15 K. The impressive transport properties of the whisker may find applications in fields like superconducting micro- and meso-structure systems.