Observation of a fluctuation-enhanced magnetoresistance in Ni81Fe19 /Ag multilayers at high current density
Stephen E. Russek, C. T. Rogers, L S. Kirschenbaum, P D. Beale, Steven C. Sanders
We report a correlation between peaks observed in the resistance versus applied magnetic field and low frequency resistance noise for Ni81Fe19/Ag giant magnetoresistance systems with dc bias current density above 10^6 A/cm^2. The magnetic noise has a 1/f -like spectrum and arises from time-dependent magnetic orientational fluctuations within the multilayer. The noise amplitude is strongly correlated with the observed magnetoresistance peaks. The data and a simple model for the fluctuations demonstrate the important role of fluctuations in determining magnetoresistance in such multilayer systems.