A theoretical study of the nonlinear thermo-magneto-electric coupling effect in magnetoelectric laminates

For the tri-layer symmetric magnetoelectric (ME) laminates made of giant magnetostrictive materials and piezoelectric materials, we established a theoretical model for the nonlinear thermo-magneto-electric coupling effect in laminates. This model was nonlinear and calculated in an iterative approach. It adopted the nonlinear magneto-thermo-mechanical magnetostrictive constitutive and the linear mechanical-thermo-electric piezoelectric constitutive and introduced the interface coupling factor to describe the strain transfer efficiency between layers. The predictions of ME coefficient versus temperature curves coincide well with experiments qualitatively and quantitatively. This model then was adopted to predict the influences of the temperature, interface coupling factor and thermal expansion coefficient of the giant magnetostrictive materials on ME coupling. It showed that: the laminates had the strongest ME effect at 0 degrees C; increasing the coupling factor would contribute to obtaining a larger ME coupling in a smaller bias magnetic field and lowering the ME effect attenuation caused by temperature variations; a smaller thermal expansion coefficient was also conducive to obtaining a larger ME coupling in a smaller bias magnetic field and decreasing the ME effect attenuation caused by temperature variations. This model can provide a theoretical basis for the preparation and application of ME devices under different temperature conditions.