Indiffusion of cobalt in amorphous Co-Zr

By use of trilayers consisting of ∼35 nm cobalt, ∼45 nm amorphous Co-Zr, and ∼35 nm cobalt, the indiffusion of cobalt into the amorphous structure was studied by means of Rutherford backscattering spectroscopy (RBS). At temperatures between 650 K and 690 K, an initially high diffusion essentially stopped after 20-40 min. annealing before equilibrium was reached. It is proposed that the effect is related to the diffusional asymmetry in the amorphous phase. The relatively immobile zirconium atoms cannot relax their configuration to permit cobalt indiffusion up to the equilibrium value.