Magnetostriction of Fe-Si-Al (sendust) alloy sputtered films.

Magnetostriction measurement was made by the optical cantilever method for Fe-Si-Al (1∼6 wt%Al, 5.5∼9.5 wt% Si, bal. Fe) alloy films prepared by d.c. magnetron sputtering. The magnetostriction, λ, for the films with approx. 90 wt%Fe concentration changes its value discontinuously by annealing higher than 300°C This annealing temperature at which sudden decrease of λ took place well corresponds to the ordering temperature in the films. The line of λ=0 determined by the present experiment in Fe-Si-Al ternary alloy films agrees fairly weel with the λs=0 line obtained by calculation in the composition range with Fe content of more than 87 wt%. Two different concentration regions, 9.0 wt%Si-5.7 wt%Al-bal. Fe and 8.0 wt%Si-4.2 wt%Al-bal. Fe, at which the soft magnetic properties (Hc ≅ 0.5 Oe, μeff > 1000 at 5 MHz) in films are realized, was found to lie at about λ ≅ 2 × 10-6. Discussion is further expanded on the difference of concentration dependences of λ=0 for the films fabricated by vacuum evaporation or sputtering.