Characterization of magnetic iron and nickel vapor deposited films

We prepared several samples of pure Fe and Ni films, evaporated in high vac uum conditions onto Cu foils or mica, ranging in thickness between 50 and 3 00 nm and measured their magnetization near the critical point in a protect ive atmosphere. The value of the T-c for the films thinner than 200 nm, gro wn on Cu, resulted lower than the respective bulk T-c Further, for these fi lms the magnetization decreases linearly with temperature near T-c. Films o f Ni grown on mica do not show a shift in T-c relative to bulk Ni. The bulk saturation magnetization is obtained for Fe and Ni films grown onto mica a t relative low fields (45 G) while on the films grown onto Cu more than 300 G are needed to obtain the bulk magnetization value. Characterization of t he films with scanning electron and transmission microscopy, X-ray photoele ctron spectroscopy, X-ray diffraction and Auger depth profiling was perform ed. These analyses indicate that the films initially are of good quality bu t heating them up to the transition temperature promotes interdifussion of the films with the Cu substrate. (C) 1999 Elsevier Science Ltd. All rights reserved.