Superconducting properties of Ca1−xRExFe2As2 (RE: Rare Earths)

We have grown rare-earth doped CaFe2As2 single crystals and characterized their normal and superconducting properties. Temperature dependence of resistivity and its absolute value suggest good metallic conduction, suppressing antiferromagnetic (AF) transition in the undoped sample. Hall coefficient shows little temperature dependence, consistent with the suppression AF state. Superconducting transitions characterized by resistivity drops in magnetic fields for both parallel to c-axis and ab-plane are reasonably sharp with a weak anisotropy parameter ∼1.75. Despite these observations, average critical current density estimated from the bulk magnetization is orders of magnitude smaller than other typical iron-based superconductors. Magneto-optical imaging confirms very inhomogeneous superconducting state.

► Superconducting properties in rare-earth doped CaFe2As2 single crystals are characterized.
► Sharp resistive transitions with small anisotropy parameter of ∼1.75 are observed.
► Average critical current density is much smaller than other iron-based superconductors.
► Magneto-optical imaging confirms very inhomogeneous superconducting state.