Superconductivity at 23 K in Pt doped BaFe₂As₂ single crystals.

We report superconductivity in single crystals of the new iron-pnictide system BaFe(1.90)Pt(0.10)As(2) 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 BaFe(2)As(2) 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 T(c), the lower critical field H(c1) = 200 mT, the upper critical field H(c2)≈ 65 T, and the slope ∂H(c2)/∂T-are comparable in value to those found in other transition metal-substituted BaFe(2)As(2) series, indicating the robust nature of superconductivity induced by substitution of Group VIII elements.