Effects of Flexoelectricity and Surface Elasticity on the Nonlinear Magnetoelectric Coupling in Unsymmetric Composites
01 Apr 2020-IEEE Transactions on Magnetics (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 56, Iss: 6, pp 1-11
TL;DR: In this paper, a finite-element model was presented to predict the static and dynamic behavior of unsymmetric magnetoelectric (ME) composites subjected to magnetic fields.
Abstract: Flexoelectricity is the development of an electric field under an applied strain gradient. This effect is highly size-dependent and is significant at nanoscales. Unsymmetric magnetoelectric (ME) composites undergo bending deformations under a magnetic field that results in non-zero strain gradients. Hence, it is important to give due consideration to flexoelectricity, along with direct piezoelectricity in these composites. This article presents a finite-element model that predicts the static and dynamic behavior of ME nanobeams subjected to magnetic fields. The effect of material nonlinearity of the ferromagnetic phase and flexoelectricity in the ferroelectric phase on the ME coupling are determined, and the obtained results show agreement with the literature. It is found that flexoelectricity results in substantially higher static ME coefficients. However, the resonant ME response is weakened by flexoelectricity. The effect of surface elasticity on the ME coupling coefficient is also investigated by making use of the Gurtin–Murdoch theory. The surface effects are found to improve the ME coefficient at bending resonance, while its effect is trivial at static and axial resonant conditions. Furthermore, the effect of load resistance on the ME voltage and charge coefficients is determined. The results indicate clear changes in the trend between short-circuit and open-circuit conditions.
Citations
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TL;DR: In this paper , a three-dimensional magnetostrictive constitutive model is used to predict the magnetomechanical behavior of magnetoelectric composites under applied magnetic fields.
Abstract: Magnetoelectric (ME) composites have posed an immense research interest over the past few decades. Their multifunctional capabilities enable a wide array of applications like field and pressure sensors, energy harvesters, gyrators, etc. The voltage developed under applied magnetic fields in these composites is governed strongly by the stress and magnetization state of the magnetostrictive phase, which needs to be characterized effectively. Towards this end, magnetostriction measurements are carried out under applied stresses in Nickel to understand its magnetomechanical response. A three-dimensional magnetostrictive constitutive model is used to predict the magnetostrictive behavior, which is later implemented in COMSOL Multiphysics® using the external material module. The FE solutions obtained are validated against analytical solutions. The model is subsequently used to obtain FE solutions for the magnetoelectric response of press-fit composites subjected to general magneto-thermo-mechanical loading. Experiments are performed on the press-fit composite to validate the voltage response predicted by the developed model, which shows a good agreement. The developed FE model is used to conduct a parametric study to quantify the effect of external loading conditions, the shape of inclusion, and the field orientation with an effort to optimize the ME response in press-fit ME composites.
4 citations
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TL;DR: In this paper, the magnetic dynamics of a ferroelectric/ferromagnetic heterostructure mediated by a charge/strain-induced magnetoelectric interaction was investigated, and the results showed the significant potential for applications of composite multiferroics and provided a feasible approach for high-performance devices that rely on electrically controlled magnetism.
Abstract: This study investigates the magnetic dynamics of a ferroelectric/ferromagnetic heterostructure mediated by a charge/strain-induced magnetoelectric interaction that exhibits a pronounced dynamic magnetic response to an electric field. In the experimental process, the epitaxial strain gave rise to electrically tunable uniaxial magnetic anisotropy, and spin accumulation at the interface led to large anisotropic damping with a C 2 υ symmetry. The results show the significant potential for applications of composite multiferroics and provide a feasible approach for high-performance devices that rely on electrically controlled magnetism.
References
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11 May 2015TL;DR: In this paper, the authors demonstrate a correlation between magnetoelectric and magnetic properties of the FM-PE composite structures and demonstrate that the magnetostriction is related to the FM layer magnetization as λ ∼ M 2.
Abstract: The magnetoelectric (ME) effect in composite structures consisting of ferromagnetic (FM) and piezoelectric (PE) layers arises due to combination of magnetostriction and piezoelectricity by means of mechanical coupling between the layers [1]. The structures generate ac voltage u being placed in an external dc bias magnetic field H and ac magnetic field h. Amplitude of the voltage is u ∼qd 31 h, where q = dλ/dH is the piezomagnetic coefficient and λ(H) in the magnetostriction of the FM layer, d 31 is the piezoelectric module of the PE layer, and h is the field amplitude. It has been shown that the magnetostriction is related to the FM layer magnetization as λ ∼ M 2. It follows, that field dependence of the ME voltage u(H) can be explained or predicted by measuring the field dependence of magnetization M(H). The aim of the present work is to demonstrate a correlation between magnetoelectric and magnetic properties of the FM-PE composite structures.
10 citations
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TL;DR: In this article, the role of transverse normal and shear deformations on enhancing the magnetoelectric (ME) coefficient of multiferroic bilayer composite beams composed of a piezolectric layer and a pizomagnetic layer was investigated.
Abstract: This paper is concerned with the exploration of the role of transverse normal and shear deformations on enhancing the magnetoelectric (ME) coefficient of multiferroic bilayer composite beams composed of a piezoelectric layer and a piezomagnetic layer. Analytical models have been derived based on the displacement field which accounts for both the transverse normal and shear deformations, Timoshenko beam theory and Euler Bernoulli beam theory. The induced flexoelectricity in the piezoelectric layer due to axial strain gradient and transverse shear strain gradient has also been taken into consideration for estimating the ME coefficient. It has been found that the contribution of transverse normal strain in the piezoelectric layer for enhancing the ME coefficient is significantly larger than that due to axial strain, transverse shear strain and flexoelectricity. For the particular values of the thicknesses of the piezoelectric layer and the piezomagnetic layer, the ME coefficient remains invariant for both thick and thin multiferroic composite beams.
7 citations
"Effects of Flexoelectricity and Sur..." refers background in this paper
...Ray [25] investigated the influence of transverse shear strain gradients on the ME coupling under a non-uniform magnetic field distribution....
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