[Ni_(80)Fe_(20)/Cu/Co/Cu] spin-valve multilayers electrodeposited on NiFe buffer layers

摘要

[Ni_(80)Fe_(20)/Cu/Co/Cu]_n spin-valve multilayers were fabricated on n-Si(111) substrates by double bath electrodeposition. A well-defined periodical structure has been demonstrated by X-ray diffraction (XRD). Scanning electron microscopy morphology shows that the electrodeposited NiFe buffer layer was continuous with a nominal thickness over 25 nm. XRD and atomic force microscopy results reveal that NiFe buffer layer has a significant effect on the texture and microstructure of spin valves. Giant magnetoresistance (GMR) of spin-valve multilayers was tested by four probe technique. The maximum room temperature GMR ratio of 5.4% was achieved at the range of 1.8-2.8 kA/m with a sensitivity of up to 2.5%/(kA/m) for NiFe(25 nm)/[Cu(3.6 nm)/Co(1.2 nm)/Cu(3.6 nm)/Py(2.8 nm)]_(30). GMR performance is proved to be highly related to the thickness of each component layer. It is considered that the variation in sublayer thickness will change the coercivity difference between adjacent magnetic layers, which drives the antiparallel alignment process of magnetizations.