1/f noise in giant magnetoresistive materials

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Abstract
The main source of 1/f resistance noise in materials exhibiting giant magnetoresistance (GMR) is the GMR effect itself. Large 1/f noise from fluctuations in the parallel vs antiparallel alignment appears when ‖dR/dH‖ is large. We have studied this noise as a function of the number of Co/Cu bilayers in multilayer samples and discuss the implications for devices. Barkhausen noise in the resistance as the field is swept through the GMR transition is used to estimate coherent domain sizes between 0.1 and 10 μm2 for a single Co layer in the multilayers. GMR noise is also seen in a Co/Ag granular system.