Prediction of tunable magnetoelectric properties in compositionally graded ferroelectric/ferromagnetic laminated nanocomposites

Abstract

The advent of modern thin-film deposition approaches has ushered in a new era of designed materials with well-controlled composition distributions, e.g., compositionally graded ferroelectric (CGFE) thin films, and thereby, it is readily accessible CGFE/FM (ferromagnetic) multilayer thin films. Being recognized this emerging class of materials, in this study, we develop a phase-field model based on the Ginzburg–Landau theory that takes into account the gradient of ferroelectric (FE) compositions in order to predict material properties of CGFE/FM thin films. The developed phase-field model is applied to investigate the effect of the FE composition gradient on magnetoelectric (ME) coupling of graded Pb(1−x)SrxTiO3/CoFe2O4 laminated nanocomposites. Two types of composition gradients are considered: inward (O-type) and outward (X-type) gradients. Unusual polarization domain structures with curved domain walls are formed in CGFE layers, which are governed by the composition gradients and distinct from typical stripe domains in homogeneous counterparts. As a result, the ME effect is strongly dependent on the composition gradient. Particularly, the ME coupling in the O-type nanocomposites increases with the increasing composition gradient, while it decreases in the X-type ones. The dependence of ME coupling on the composition gradient originates from the distinguishable energy distributions in O-type and X-type nanocomposites. This work, therefore, provides a strategy to design the ME effect via the configuration of the composition gradient.

Self‐biased magnetoelectric composite for energy harvesting

“…The ferroelectric and ferromagnetic phases in homogeneous ME composites exhibit symmetrical electrical and magnetic hysteresis loops, while continuously or discretely changing the composition or phase of such composite along a certain spatial dimension. Polarization gradients related to the changes in electrical components cause the built‐in potentials and the hysteresis loops to shift along the polarization axis 50–52 . Similar concepts have also been extended to hierarchical ferromagnetic systems with spatial variations in saturation magnetization, resulting in internal magnetostatic potentials, that is, the built‐in magnetic field ( H int ) internally formed along the graded direction and the hysteresis loop displacement 53–55 .…”

“…Polarization gradients related to the changes in electrical components cause the built-in potentials and the hysteresis loops to shift along the polarization axis. [50][51][52] Similar concepts have also been extended to hierarchical ferromagnetic systems with spatial variations in saturation magnetization, resulting in internal magnetostatic potentials, that is, the built-in magnetic field (H int ) internally formed along the graded direction and the hysteresis loop displacement. [53][54][55] With respect to the structure of a functionally ferromagnetic graded ME composite, the total dc magnetic field (H total ) consists of an external H dc and a built-in magnetic field (H int ).…”

Polymer‐/Ceramic‐based Dielectric Composites for Energy Storage and Conversion

“…Composite materials containing ferroic orders such as ferroelectricferromagnetic and ferroelectric-multiferroic composite systems are provoking much research activity due to their profound physics and potential applications in sensors, memories, and spintronics. [208][209][210][211] However, these composites are out of the scope of this review, and the progress in these composites has been summarized in the recent reviews. [208][209][210] One has to note that ferroelectric composite materials have shown great potentiality for many other new applications such as ferroelectric memory devices, [212,213] flexo-photovoltages, [213] and advanced nano-/micro-electromechanical systems based on flexoelectric composites.…”