Dielectric properties of compositionally graded Ba1-xSrxTiO3 thin films described by the transverse-field ising model

This investigation reports on the phase transition and dielectric properties of compositionally graded Bat-xSrxTiO3 (BST) thin films with x decreasing from 0.20 to 0.10 in successive slabs, based on the transverse-field Ising model (TIM) within the framework of mean field theory. The random bond model of related parameters is applied to mimic doping. The effect on polarization and dielectric susceptibility arising from a gradient in composition is taken into account. The peaks of dielectric susceptibility versus temperature become comparatively flat by modulating appropriate thickness in each slab in compositionally graded BST thin films, which means that the thickness may weaken the effect of composition gradient. When increasing the number of slabs of thin films, the dielectric susceptibility shows good temperature stability in a wide temperature range, which is useful for reducing the temperature coefficient of dielectric susceptibility without depressors.