The stressed state induces changes in many physical properties, especially, an appreciable change may occur in the magnetic and magnetostrictive characteristics of the magnetostrictive layer made of a ferromagnetic nickel (Ni) with cubic symmetry. The idea behind our present study is that both the magnetostrictive and piezoelectric layers of the laminate are in a stressed state as a result of the bonding. This discrepancy is overcome by introducing a correction factor for. However, this theoretical prediction does not agree well with the values of retrieved from the measurements of see. Often it is tacitly assumed that is defined by the derivative of the magnetostrictive strain with respect to the magnetic field of the bare magnetic material in the bias magnetic field and, therefore, can be estimated as the magnetostrictive strain at magnetic saturation divided by the corresponding magnetic saturation field.
In this framework, one of the principal parameters which enter the previous is the piezomagnetic coefficient. In addition, in most research on the ME effect in magnetostrictive/piezoelectric composites carried out so far, it was assumed that constitutive relations for both piezoelectric and magnetostrictive single phase are linear. Various numerical methods were proposed to study the ME effect in the multiferroic composite including the finite-element method (FEM) modeling the FEM modeling was also applied to the composite multiferroic device analysis.
However, in this approach, depends only on the fractional thicknesses of the piezoelectric and magnetostrictive layers and not on the lateral dimensions of the laminate, which contradicts the new experimental data. As was argued, those expressions for are in fact leading asymptotic ones at the lateral-to-transverse dimensions ratios tending to infinity, which result from neglecting the true boundary conditions for all the previously mentioned physical fields. The analytical expressions for the ME coefficient of such a configuration are obtained so far under the assumption of homogeneity of electric, magnetic, and elastic field and employing boundary conditions for mechanical stress in the integral meaning at the structure facets. The simplest type of the ME laminate comprises two parallel magnetostrictive and piezoelectric plates well bonded to each other. The strong ME effect was recently observed in artificially fabricated multiferroic composites, where the two different-phase materials, that is, the piezoelectric and magnetostrictive single-phase materials, are bonded together. Magnetostrictive-piezoelectric laminates exhibiting magnetoelectric (ME) effect have drawn increasing interest due to their potential for many modern devices, such as sensors, gyrators, and energy harvesters. The results of the simulations are compared with the experimental data and with a widely known analytical result for the induced magnetoelectric voltage. The reported results take into account the finite-size effects of the structure, such as the fringing electric field effect and the demagnetization, as well as the effect of the finite conductivity of the Ni layers on the output voltage. For approaching the real materials’ properties, a measured magnetization curve of the Ni plate is used in the computations. A bias magnetic field is simulated as being produced by two permanent magnets, as it is done in real experimental setups.
#Field continuity in comsol 5.3 software#
Using the finite-element method-based software COMSOL, we numerically calculate the induced voltage between the two faces of the PZT piezoelectric layer, by an external homogeneous small-signal magnetic field threading the three-layer Ni/PZT/Ni laminate structure. We consider a magnetoelectric laminate which comprises two magnetostrictive (Ni) layers and an in-between piezoelectric layer (PZT).
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