Electron spectroscopic evidence of metastable alloy formation of Ag and Au in Co

High-resolution x-ray photoemission spectroscopy measurements of the conduction bands of dilute noble metal/Co metastable alloy films show a narrowing of the noble-metal d bands at concentrations below 6 at. % of noble metal consistent with coordination of the noble metal atoms with Co. Such alloying contrasts strongly with Ag and Au precipitation at higher concentrations, and with conventional metallurgical experience. It is consistent, however, with recent observations of modified interlayer exchange coupling in magnetic trilayer structures doped with noble-metal atoms [U. Ebels et al., Phys. Rev. B 58, 6367 (1998)].