Evolution of Gd Thin Film Structure Due to Amorphization by Co Deposition

Multilayers of Gd/Co produced by sputter deposition are observed to be amorphous for a wide range of bilayer periods. This structure is largely the result of an amorphization reaction during the deposition between crystalline Gd and newly arriving Co atoms. We explore this reaction by producing multilayers of Gd/Co/Cr, and examining the resulting microstructure. We observe both interfacial disordering due to a layer thickening mechanism and evidence for growth of the amorphous phase from Gd grain boundaries. The reaction is enhanced by the presence of a large number of crystalline defects in the Gd layers.