Magnetic properties of interfacial layers in Co/Ge(111) thin films

As Co deposited on a Ge(111) substrate, Co L 3 M 45 M 45 Auger line shifts to higher kinetic energy. This shift can be explained by the difference of the electronegativities of Co and Ge atoms and gives the spectroscopic evidence of the interfacial compounds. Cryogenic treatments on nonferromagnetic Co films (< 9.5 ML) cause a transition to be ferromagnetic and reveal the existence of a pure cobalt layer in the Co/Ge(111) system. The thickness dependence of Curie temperature was determined for the cobalt coverage between 6.3 and 10.5 ML.