Annealing study on nano Co-AlO granular films

In this work, we carry out a systematic study on the annealing effects of microstructures and MR ratio for a series of nano Co-AlO granular films. Via the techniques of transmission electron microscope, electron spin resonance and X-ray photoelectron spectroscopy, it is unraveled that both the geometrical and the magnetic microstructures of these films do not change much with annealing temperature. On the other hand, the compositional evolution inside the film may be a key issue for the degradation of MR ratio at temperature higher than 300 grad C. (Authors)