Evidence for three-dimensional Fermi-surface topology of the layered electron-doped iron superconductor Ba(Fe1-xCox)(2)As-2

The electronic structure of electron-doped iron-arsenide superconductors Ba(Fe1-xCox)(2)As-2 has been measured with angle-resolved photoemission spectroscopy. The data reveal a marked photon energy dependence of points in momentum space where the bands cross the Fermi energy, a distinctive and direct signature of three dimensionality in the Fermi-surface topology. By providing a unique example of high-temperature superconductivity hosted in layered compounds with three-dimensional electronic structure, these findings suggest that the iron arsenides are unique materials, quite different from the cuprates high-temperature superconductors.