Magnetostriction Constants of High Bs CoZr Amorphous Films

The effect of small amounts of Zr in CoZr films is discussed. It was found that a Zr concentration of 4 at% or less caused the magnetostriction constant to decrease to 1 × 10^-6. The magnetostriction constant was measured by making one edge of the film stationary, applying a 20 Oe magnetic field in the easy and hard axis directions and measuring the displacement of the free edges. The magnetorestriction constant of films with a Zr concentration of 4.8 at% and with various film thickness was nearly constant (it was somewhat smaller for thinner films), but after heat treatment this constant decreased without saturating. The value decreased with decreases in the Zr concentration. The magnetostriction constant of CoZr films with a Zr concentration of 3.4 ~ 4 at% decreased to approximately 1 × 10^-6.