Magneto-acoustic Bragg diffraction of magnetostatic waves (abstract)

Abstract

This experimental investigation is concerned with the study of diffraction of magnetostatic waves (MSWs) by surface acoustic waves (SAWs) when both types of waves travel in the same yttrium iron garnet (YIG) film. The SAWs are used to set up a space and time modulation of the medium in which the MSW propagates. Because of their mostly isotropic propagation properties in the plane of the film, magnetostatic forward volume waves are employed in this investigation. In the configuration used, MSW is launched at different angles with respect to the acoustic beam. Different MSW microstrip transducers are used to detect the scattered and unscattered MSW signals. The frequency of the Bragg-diffracted MSW signal is shifted by an amount equal to the SAW frequency. The MSW microstrip transducers are 65-μm-wide and 15-μm-thick copper lines on an RT/duroid substrate of thickness of 5 mils and εr=10.5. A YIG film of 120 μm thickness is placed in contact with the microstrip structure described above. A dc magnetic field is applied normal to the film plane. The SAW is excited using bulk wave transducers (36° Y-cut lithium niobate) placed on plexiglass wedges to convert the bulk acoustic waves into SAW. Our experimental results are in good agreement with calculations based on Bragg’s diffraction. Different device applications that employ this effect for spectrum analysis1 and frequency shifting2 have been proposed recently.