Determination of the local order in amorphous cobalt films

The local atomic structure of amorphous cobalt films prepared by vapor condensation on a low-temperature substrate is determined by extended x-ray-absorption fine structure. The deduced radial distribution function corresponding to the first shell of neighbors is broadened compared to that of crystalline cobalt and is asymmetrical. The measured profile allows us to conclude the existence of a true amorphous monometallic sample and compares well with the calculated one assuming a random packing of hard spheres. The existence domain of this structure is then outlined.