Pressure versus Concentration Tuning of the Superconductivity in Ba(Fe1-xCox)2As2

In the iron arsenide compound BaFe2As2, superconductivity can be induced either by a variation of its chemical composition, e.g., by replacing Fe with Co, or by a reduction of the unit-cell volume through the application of hydrostatic pressure p. In contrast to chemical substitutions, pressure is expected to introduce no additional disorder into the lattice. We compare the two routes to superconductivity by measuring the p dependence of the superconducting transition temperature T-c of Ba(Fe1-xCox)(2)As-2 single crystals with different Co content x. We find that T-c(p) of underdoped and overdoped samples increases and decreases, respectively, tracking quantitatively the T-c(x) dependence. To clarify to which extent the superconductivity relies on distinct structural features we analyze the crystal structure as a function of x and compare the results with that of BaFe2As2 under pressure.