Effect of new materials as under and cap layers on thermal stability of synthetic bottom spin valves

We investigated the thermal stability of the Ta-, ZrAl- and TiAl- based synthetic bottom spin valves. In the as- deposited state, the MR ratios of ZrAl- and TiAl- based synthetic SVs ( SSV) are similar to that of the Ta- based SV. However, after annealed at 400 degrees C for 10 min, the MR ratio of Ta- based SV decreased by 42.5% ( from 7.43% to 4.27%). On the other hand, the MR ratio of ZrAl- and TiAl- based SSVs increased 0.3% ( from 7.37% to 7.39%) and 13.3% ( from 7.47% to 8.46%), respectively. Auger depth pro. le clearly showed that ZrAl- and TiAl- based SSVs have higher interdiffusion resistance than Ta- based SV. Especially, diffusion of Mn from antiferromagnet layer to pinned layer was suppressed in TiAl- based SVs. The root- mean- square ( RMS) roughness of the TiAl layer ( 0.11 nm) was much smaller than those of the ZrAl ( 0.16 nm) and Ta layer ( 0.43 nm). Due to high affinity of Ti or Al with oxygen, very stable and dense TiAl-oxides were formed at the surface during annealing. Thermal stability of TiAl- and ZrAl- based SSVs was enhanced due to surface uniformity and high passivity of TiAl- and ZrAl- oxides. (c) 2006 Published by Elsevier B.V.