Doping effect on the physical properties of Ca10Pt3As8(Fe2As2)5 single crystals

Ca₁₀Pt₃As₈(Fe₂As₂)₅ is a unique parent compound for superconductivity, which consists of both semiconducting Pt₃As₈ and metallic FeAs layers. We report the observation of superconductivity induced via chemical doping in either Ca site using rare-earth (RE) elements (RE  =  La, Gd) or Fe site using Pt. The interlayer distance and the normal-state physical properties of the doped system change correspondingly. The coupled changes include (1) superconducting transition temperature T _c increases with increasing both doping concentration and interlayer distance, (2) our T _c value is higher than previously reported maximum value for Pt doping in the Fe site, (3) both the normal-state in-plane resistivity and out-of-plane resistivity change from non-metallic to metallic behavior with increasing doping concentration and T _c, and (4) the transverse in-plane magnetoresistance (MR_ab) changes from linear-field dependence to quadratic behavior upon increasing T _c. For La-doped compound with the highest T _c (~35 K), upper critical fields (H_c2^ab , H_c2^c ), coherence lengths (ξ _ab, ξ _c), and in-plane penetration depth (λ _ab) are estimated. We discuss the relationship between chemical doping, interlayer distance, and physical properties in this system.