TEMPERATURE DEPENDENCE OF ANISOTROPY IN Co/X(Pt, Au, Ag, Ni) MULTILAYER FILMS

Temperature dependences of effective perpendicular anisotropy (PA) K_u and inter-face energy K_s for Co/X(Pt, Au, Ag, Ni) multilayer films(MFs) as well as of spontaneous magnetization M_s for Co/Pt and Co/Au MFs are reported. The dependence of K_s on T dis-tinguishes between Go/Au, Co/Ni and Co/Pt, Co/Ag MFs, i.e., K_s of the former decreases with the increase of T, but it increases for the latter. Co/Pt MFs with the perpendicular anisotropy possess a large enhancement of M_s at low temperature, but there is not any en-hancement for Co/Au MFs. We have discussed the source of PA in Co/Au and Co/Pt MFs and speculated that the strain due to the lattice mismatch may be the main cause of PA in Co/Au MFs, but it is not for Co/Pt MFs.