Measurement of the magnetostriction constants of amorphous thin films on kapton substrates

The saturation magnetostriction constants of thin films of amorphous Co39Ni 31Fe8Si8B14 and CoZrTb have been measured either by the small angle magneti zation rotation (SAMR) method or by the initial susceptibility method. The SAMR method is used for the soft materials. When the material is magnetical ly hard or has a strong perpendicular anisotropy, the initial susceptibilit y method is used. It is found that the amorphous Co39Ni31Fe8Si8B14 prepared by ion beam deposition from an alloy target shows very soft magnetic prope rties and has a very small negative saturation magnetostriction, lambda(s), of -1 x 10(-7). Sputtered films of CoZrTb show a strong perpendicular anis otropy when the concentration of Tb is high. We have found that the SAMR me thod can be applied to CoZrTb films when the Tb content is low. The saturat ion magnetostriction constant of a sputtered film of Co78.4Zr20.8Tb0.8 is 2 x 10(6). When the Tb content is high, however, the initial susceptibility method is used to measure magnetostriction. (C) 1998 American Institute of Physics.