Annealing effects on GMR multilayer films

The annealing effects on GMR of electron-beam evaporated [NiFe/Cu](BL) mult ilayer films (10, 12 and 14 bilayers) were studied. The as-deposited multil ayer films give a GMR smaller than 0.6% but can be enhanced by further anne aling. The multilayer films were annealed in a vacuum at 300 degrees C for 2.5 h with the pressure < 1 x 10(-7) mbar and the GMR of order of similar t o 1% was achieved. However, some samples were annealed in the flowing argon at the same temperature and period of time, giving an improved GMR change up to similar to 4-4.5% similar to that presented by Smith et al. [N. Smith , A.M. Zeltser, M.R. Parker, GMR Multilayers and Head Design for Ultrahigh Density Magnetic Recording, IEEE Trans, Magn. 32 (1996) 135]. The oxidisati on on the surface of the films is thought to cause this critical difference . The periods of annealing time can also affect the GMR which increases dra matically as the film is annealed up to 1 h and tends to be constant at lon ger times up to 2.5 h. Application of a forming field during annealing is f ound Is induce uniaxial anisotropy. (C) 2000 Elsevier Science S.A. All righ ts reserved.