Domain observations on NiFeCo/Cu/NiFeCo-sandwiches for giant magnetoresistive sensors

摘要

We prepared NiFeCo-Cu-NiFeCo GMR sensor structures with crossed anisotropy. The ferromagnetic layers are weakly coupled. The measured GMR ratio is about 1.2%-smaller than the ratio derived from measurements on similar spin-valve structures. To explain the poor performance we studied the domains in the coupled ferromagnetic layers by Kerr microscopy. The magnetization processes are strongly influenced by the remaining weak ferromagnetic coupling and the occurrence of compensated wall structures. These irregularities lead to reduced GMR ratios. Also the formation of 360/spl deg/-walls can be observed.