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

Abstract

The saturation magnetostriction constants of thin films of amorphous Co39Ni31Fe8Si8B14 and CoZrTb have been measured either by the small angle magnetization rotation (SAMR) method or by the initial susceptibility method. The SAMR method is used for the soft materials. When the material is magnetically hard or has a strong perpendicular anisotropy, the initial susceptibility method is used. It is found that the amorphous Co39Ni31Fe8Si 8B14 prepared by ion beam deposition from an alloy target shows very soft magnetic properties and has a very small negative saturation magnetostriction, λs, of - 1 × 10-7. Sputtered films of CoZrTb show a strong perpendicular anisotropy when the concentration of Tb is high. We have found that the SAMR method can be applied to CoZrTb films when the Tb content is low. The saturation magnetostricition constant of a sputtered film of Co78.4Zr20.8Tb 0.8 is 2 × 106. When the Tb content is high, however, the initial susceptibility method is used to measure magnetostriction. © 1998 American Institute of Physics.