Phase Control of Magnetic Susceptibility of Multiferroic Composites

Dynamic magnetic susceptibility of a laminated composite of FeSiB/Pb(ZrTi)O3/FeSiB was measured. Alternating magnetic and electric fields in the ultrasonic range were simultaneously applied to excite the first mode of the longitudinal resonant vibrations of the composite sample. Significant enhancement of the susceptibility was observed when both fields had the same phase. However, the susceptibility was reduced by almost two orders of magnitude when the phase between the electric and magnetic field was shifted by 180°. This effect is interpreted in terms of combined magnetomechanical and electromechanical resonances that cause large dynamic strains in the magnetostrictive FeSiB ribbons and give rise to large changes of the magnetization when the strains in the magnetic and piezoelectric act in unison. In contrast, when the excitation fields have different phases, the strains in both materials oppose each other and the magnetoelastic contribution to the susceptibility is suppressed. The phase control of the magnetic susceptibility offers an interesting mechanism for applications, where fast modulation or rapid ON/OFF switching of susceptibility signal is required.