Effect of Thickness Ratio on the Magnetic Properties of the Magnetostrictive Thin Film Composite

Abstract

Magno-elastic coupling characteristics in giant magnetostrictive thin films depend on a myriad of factors, comprising variability in Young’s modulus, thermally induced pre-stresses, the direction of the applied magnetic field and the substrate to film thickness ratio, demagnetization field etc. Due to the aforementioned reasons, the giant magnetostrictive thin films usually display characteristics that may contrast with the bulk giant magnetostrictive materials. This work studies magnetostrictive film on a compliant substrate using a generalized 3-D magneto-thermo-elastic nonlinear constitutive model with the elasticity theory to include such stimuli sensitive coupled magneto-thermo-elastic response. The numerical simulation of the magnetostrictive film on the compliant substrate in the form of a cantilever shows good agreement with the existing experimental data. The substrate and film thickness ratio effect on the thermal strain, Young’s modulus, magnetization and magnetostriction of films was meticulously analyzed. It has been revealed that the magneto-elastic responses rely strongly on the substrate-to-film thickness ratio. Thus, it is possible to obtain the tunable properties by controlling the composite film's thickness ratio in the design state of smart devices.