Effect of leakage current on magnetoelectric effect of 0-3 multiferroic composites based on an equivalent circuit model

Abstract

In 0-3 multiferroic composites, the content of ferromagnetic particles with conductive properties significantly influences their magnetoelectric (ME) performance. The occurrence of leakage current (Lc) at high contents is a crucial factor affecting the ME properties of such composites. Establishing a rational and effective theoretical model to analyze and predict the impact of Lc on their ME performance is of paramount theoretical significance for expanding the applications of these composites. In pursuit of this objective, by introducing conduction currents, magneto-electric-mechanical/electro-magnetic-mechanical coupling factor, and resistive components, an equivalent circuit model is built to analyze the direct and converse ME effects of this composites. Meanwhile, the general analytical expressions of various effective properties are obtained. By introducing factors with combined exponential and linear decay characteristics into the piezoelectric coefficient, our theoretically calculated results quantitatively agree with experimental data. On this basis and considering the effects of displacement current and conduction current, we utilized our equivalent circuit model to calculate the ME coefficients, which showed high consistency with experimental results. Especially at high volume fractions, our computed results accurately reflected the sharp decline characteristics of the ME coefficients caused by Lc. This demonstrates the accurate and reasonable explanation provided by our model for such ME problems. In addition, the optimal set of volume fractions and magnetic fields that maximize the direct ME coefficient is obtained. This study fills a theoretical gap in the equivalent circuit method for 0-3 multiferroic composites and gives an analytical solution for the ME coefficients and provides theoretical guidance and support for the application of this composites.