Observation of large wave vector interface spin waves: Ni(100)/fcc Co(100) and Cu(100)/Co(100)

Using electron energy loss spectroscopy, we have probed the spin waves of fcc(100) cobalt after capping with 1–3 atom layers of pseudomorphic nickel or up to 12 atom layers of copper. The intensity decay of the spin wave signal is quantitatively described by the mean-free path of the incident and the scattered electron within the capping layer. The observed spin waves are therefore localized at the cobalt side of the Co/Ni and Co/Cu interfaces. Compared to the free cobalt surface, the interface spin waves are downshifted in frequency. The effect is attributed to a reduced exchange interaction between cobalt atoms at the interface.