Abstract
The thermal stability of the giant magnetoresistance (GMR) effect was examined in Co/Cu multilayers fabricated on various buffer layers with differing interfacial roughnesses and crystallographic orientations. In multilayers on body-centered cubic (BCC)-Cr90Ni10 and (BCC)-Cr80Fe20 buffer layers, the MR ratio is maintained at over 50% up to the annealing temperature of 300°C. On the other hand the MR ratio of the multilayer fabricated on δ-Cr63(Ni-Fe)37 buffer layer and that of the multilayer fabricated with introducing impurity oxygen into the sputtering atmosphere, decreased significantly after the thermal annealing at relatively lower temperature. Secondary ion mass spectroscopy (SIMS) analysis for the multilayer on (BCC)-Cr90Ni10 buffer layer shows a very small amount of atomic diffusion of buffer layer elements into the multilayer after thermal annealing, in comparison with data for multilayers fabricated on a δ-Cr63(Ni-Fe)37 buffer layer. Through detailed structural analysis of the multilayers, it was concluded that the interfacial flatness at grain boundaries should be improved to prevent atomic inter-diffusion and to achieve high thermal stability of the GMR effect in Co/Cu multilayers.
