Abstract
The relation between soft magnetic properties and local anisotropy fluctuation, which is strongly connected with the microstructure of the films, was systematically examined for Ni-Fe-Nb alloy films with nearly 50 wt%Ni. According to the micromagnetic ripple theory by Hoffmann, effective magnetic anisotropy Ueff in each of the grains decreases drastically with increases in the number of grains N within the coupling volume. Experimental results show local anisotropy fluctuation for Ni-Fe-Nb alloy films strongly depends on Ueff/Ku, and it decreases with decreasing Ueff/Ku. Therefore, to realize high initial permeability in these films, it is necessary to increase N within the coupling volume by decreasing the size of the grains. In the case of Ni-Fe-Nb alloy films, decreasing the size of the grains less than 200A to obtain high initial permeability more than 2000 is needed.
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