Superconductivity at 23 K in Pt doped BaFe2As2 single crystals

We report superconductivity in single crystals of the new iron-pnictide system BaFe1.90Pt0.10As2 grown by a self-flux solution method and characterized via x-ray, transport, magnetic and thermodynamic measurements. The magnetic ordering associated with a structural transition at 139 K present in BaFe2As2 is completely suppressed by substitution of 5% Fe with Pt and superconductivity is induced at a critical temperature T-c = 23 K. Full diamagnetic screening in the magnetic susceptibility and a jump in the specific heat at T-c confirm the bulk nature of the superconducting phase. All properties of the superconducting state-including the transition temperature Tc, the lower critical field H-c1 = 200 mT, the upper critical field H-c2 approximate to 65 T, and the slope partial derivative H-c2/partial derivative T-are comparable in value to those found in other transition metal-substituted BaFe2As2 series, indicating the robust nature of superconductivity induced by substitution of Group VIII elements.