Electronic phase diagram of disordered Co doped BaFe2As2−δ

Superconducting and normal state transport properties in iron pnictides are sensitive to disorder and impurity scattering. By investigation of Ba(Fe 1− x Co x ) 2 As 2−δ thin films with varying Co concentrations we demonstrate that in the dirty limit the superconducting dome in the electronic phase diagram of Ba(Fe 1− x Co x ) 2 As 2−δ shifts towards lower doping concentrations, which differs significantly from observations in single crystals. We show that especially in the underdoped regime superconducting transition temperatures higher than 27 K are possible.