High Sensitive Co/Cu/Co Sandwiches with Ni Buffer Layers

Abstract

Giant magnetoresistance (GMR) effect in Co(5nm)/Cu(3.5nm)/Co(5nm)sandwiches with different thickness Ni buffer layers was investigated. It was found that the usage of a Ni buffer layer could enhance the MR ratio and sensitivity of the sandwich significantly. MR ratios from 3.5% to 5.6% were obtained and MR curves were found to saturate in a field about 30 Oe. Furthermore, field sensitivities larger than 1%/Oe were observed in these sandwiches. X-ray diffraction analysis showed that (111) texture was formed in Ni buffered sandwiches. Atomic Force Microscope images also indicated that interface roughness of the sandwiches could be reduced by the Ni buffer layer. It was considered that Ni buffer layer played an important role in the improvement of magnetic characteristic, MR ratio and sensitivity of the sandwiches.