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.