Abstract
The MR ratio of a cross geometrical ferromagnetic tunnel junction with a spin-valve-like structure of Ni-Fe/Co/Al-O/Co/Ni-Fe/Fe-Mn/Ni-Fe is dependent upon annealing temperature. In this study we investigate the cause of this dependance using I-V measurements, X-ray photoelectron spectroscopy (XPS), and X-ray reflectivity. The behavior of the MR ratio as a function of annealing temperature agrees well with the behavior of barrier height estimated from I-V curves. Therefore we consider that the dependence of MR ratio on annealing temperature is caused by the dependence of barrier height on annealing temperature. From XPS and X-ray reflectivity, we find that the dependence of barrier height on annealing temperature is caused by the change of oxidization of the Al-O layer.
