The effect of the annealing temperature on the magnetostrictive properties of FeCo alloy thin films on quartz glass was systematically investigated. The saturation magnetostriction was 56 ppm for the Fe32Co68-sputtered thin film quenched from 673 K, and it increased to 159 ppm with increasing annealing temperature up to 1073 K. The magnetostriction above 1093K significantly decreased with the emerging fcc phase in the FeCo alloy. SEM images showed that the crystal grains present in the fcc phase aggregated to form a discontinuous surface, which resulted in a decrease in the effective magnetostriction. Measurements of the magnetic properties by vibrating sample magnetometer and magnetic force microscopy revealed the enhancement of the magnetization at the crystal grain boundaries of FeCo alloy thin films with large magnetostriction. Thus, the heterogeneity of the magnetization can play a key role in inducing the large magnetostrictive effect.
ASJC Scopus subject areas