Optimization of magnetoresistive sensitivity in electrodeposited FeCoNi/Cu multilayers

Giant magnetoresistive (GMR) multilayers with high GMR sensitivity might find application in low-end magnetic sensors. Electrodeposition of FeCoNi/Cu GMR multilayers directly onto n-type silicon was carried out from a single electrolyte and their magnetotransport properties were investigated. Inhomogeneous dissolution of the ferromagnetic (FM) layer during Cu sublayer deposition has an important role in determining the shape of the GMR characteristics; lower dissolution promotes sharper interfaces and larger slopes of the GMR versus field curve at low fields. An increase of the Fe content in the FM sublayers reduces coercivity but promotes selective dissolution and degrades interface sharpness. Electrodeposition conditions are optimized to achieve a maximum GMR of 9% saturated at <0.5 kOe, and a maximum GMR sensitivity of over 0.11%/Oe in the field range 5-15 Oe with a saturation GMR of 6.1%.