Tuning of bandwidth by superposition of bending and radial resonance modes in bilayer laminate composite

Abstract

Though the magnetoelectric (ME) coupling strength found to be enhanced at electromechanical resonance, the narrow bandwidth limits its device functionality. Hence, widening the resonance bandwidth without affecting the ME coupling strength is essential for practical applications. This paper explores the possibility of tuning the resonance bandwidth by superimposing radial mode over bending mode in simple asymmetric bilayer laminate structure. Such superposition of modes can be realized by varying the thickness of the ferroelectric layer in ME composite. In order to examine this, (BiScO3-PbTiO3)-NiFe2O4 bilayer ME composite with varying thickness were fabricated and characterized with direct and converse ME measurements. As expected, variation in thickness of the bilayer tunes the second bending mode to overlap with the radial mode. The direct and converse ME studies demonstrate that the resonance bandwidth is modulated due to overlapping of modes. The off-phase superposition of resonance and anti-resonance frequency of radial and bending mode is essential for bandwidth tuning.