Magnetically tunable ultrasonic transducers for shear waves

Single crystal platelets of FeBO₃ are used as magnetoelastically excited shear wave transducers in the 10–100MHz region. Due to a strong dependence of the elastic stiffness on an applied magnetic dc field the resonance frequency is magnetically tunable in a region of about 25 percent around the centre frequency. A pulse-echo experiment was used to compare the conversion efficiencies of the FeBO₃ transducer and a conventional quartz transducer. The insertion losses were found to be approximately equal for both transducers and in accordance with the calculated values.