Low-magnetic-threshold acoustic switch fabricated utilizing magnetoelastic FeNi/brass phononic crystal plate

A low-magnetic-threshold acoustic switch (AS) fabricated using a magnetoelastic FeNi/brass phononic crystal (PC) plate is presented. Since the small differences in elastic characteristics between brass and FeNi lead to the strong elastic wave coupling, the changes in the elastic and geometrical characteristics of FeNi greatly affect band structures and corresponding wave transmissions. Consequently, the magnetic field threshold for turning on/off the presented AS is approximately 1/126 as large as that in the previous AS fabricated using a magnetoelastic Terfenol-D/epoxy PC. Moreover, this proposed AS exhibits an 89.9% contrast rate at 249.3 kHz.