Abstract
Magnetoelectric (ME) coefficients for bending excitation in static magnetic fields and the bending response of multilayer composites with alternating magnetostrictive (MS) and piezoelectric (PE) layers on a substrate are investigated systematically. Theory and closed-form analytic solutions for the static magnetoelectric and the bending response coefficients are presented. Results of systematic variation of layer numbers, layer sequences, PE volume fractions, substrate thicknesses, and four different material systems (employing FeCoBSi, Terfenol-D, AlN, PZT, and Si) are given for a fixed total composite thickness of 5μm. Among more than 105 structures investigated the greatest static ME coefficient of 62.3 V/cmOe is predicted for all odd layer number FeCoBSi-AlN multilayer composites on a Si substrate at vanishing substrate thickness and a PE material fraction of 38%. Varying the substrate thickness from 0μm to 20μm and the PE fraction from 0% to 100%, broad parameter regions of high ME coefficients are found for odd and large layer number nanocomposites. These regions are further enhanced to narrow maxima at vanishing substrate thickness, which correspond to structures of vanishing static bending response. For bilayers and even layer number cases broad maxima of the ME coefficient are observed at nonzero substrates and bending response. The optimal layer sequence and PE fraction depend on the material system. Bending response maxima occur at zero Si substrate thickness and nonzero PE fractions for bilayers. For multilayers nonzero Si substrates and zero PE fractions are found to be optimal. Structures of even ME layer numbers of PE-MS...Sub layer sequence display regions of vanishing bending response with large ME coefficients, i.e., produced by longitudinal excitation.
Highlights
For this purpose we evaluate FeCoBSi-AlN multilayer nanocomposites on a Si substrate
In summary we have developed an analytic model for the bending mode static magnetoelectric coefficient, the magnetic bending response coefficient, the bending radius, and the zero strain position in the presence of external fields for multilayer nanocomposites on a substrate
Using the closed form solutions yielded by the model, we systematically investigated the effect of varying layer number, layer sequence, piezoelectric volume fraction, substrate thickness, and using different piezoelectric and magnetostrictive materials in the layered ME nanocomposite
Summary
Layered systems [2], bilayer composites on a substrate currently produce record dynamic ME coefficients of several 100 V/cmOe. These sensors operate in bending mode at resonance, whereby resonance-enhancement contributes significantly to the sensitivity. Layered systems have the additional benefit to be compatible with MEMS production techniques. Magnetoelectric multilayer nancomposites have been pursued for improved interface coupling. Further reasons for pursuing multilayers are, e.g., enhanced charge collection from piezoelectric layers, enhanced ferroic coupling, magnetic noise reduction, or enhanced mechanical durability of thin cantilevers. The net bending moment about the y-axis contributed from x-direction stresses of surface elements in the yz-plane for all layers of the multilayer and substrate stack must vanish, i.e., ∫ zTxx dz = 0 In detail this yields the following integral equation for all layers of the stack:. Equations [6] and [8] can be solved for the zero strain position in the presence of nonzero external fields zN and and the bending radius R This yields the closed form solutions for zN and R in terms of external fields, material constants, and multilayer nanocomposite and substrate geometries. D H3 results were found to agree with the results of the original calculation program for numerous nontrivial cases
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
