Nanoanalysis of Interreactions
Thermal stability of GMR sensor devices
The thermal stability of sensor devices based on the giant magneto-resistance effect is important for
applications at elevated temperatures. We studied atomic transport and segregation by means of atomprobe
tomography in spin-valve layer systems Cu/FeNi/Cu/Py and GMR Cu/Py multilayers. Interfacial mixing
and grain boundary diffusion on the length scale of a few nm only were demonstrated. As the important
mechanism of degrading the magneto-resistivity a volume diffusion driven by non-equilibrium point defects
were identified. In addition, a recrystallization mechanism was observed that proceeds at 350oC
and higher temperatures. A variation of lattice mismatch by changing the compositon of permalloy definitely
proves that this recrystallization is due to mismatch induced stress and the elastic anisotropy of the related
materials.
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