Magnetostriction of Fe-Al-Si alloy sputtered films

Magnetostriction measurements were made by the optical cantilever method for Fe-Al-Si (1∼6wt% Al, 5.5∼ 9.5wt% Si, bal. Fe) alloy films prepared by d.c. magnetron sputtering. The magnetostriction, λ, for the films with approx. 90wt% Fe concentration changes its value remarkably with annealing higher than 300°C. This annealing temperature at which sudden decrease of λ takes place corresponds well to the ordering temperature in the films. The line of λ=0 determined by the present experiment in Fe-Al-Si ternaly alloy films agrees fairly well with the λs=0 line obtained by calculation in the composition range with Fe content more than 87wt%. Two different film concentration regions, 5.7wt% Al-9.0wt% Si-bal.Fe and 4.2wt% Al-8.0wt% Si-bal. Fe, at which the soft magnetic properties ( Oe, μeff >1000 at 5 MHz) are realized, were found to lie at about . The difference of concentration dependences of λ=0 for the films fabricated by vacuum evaporation and by sputtering are discussed.