Magnetic Field Control of Lithium Niobate Thin Film Acoustic Delay Lines

Benefiting from mature manufacturing processes and well-defined resonance frequencies, integrating magnetic materials into acoustic radio frequency (RF) devices has opened up new avenues for controlling and enhancing the performance of acoustic devices. This study created a magnetically controllable Lamb wave delay line with a fundamental frequency approximately 478 MHz, using a multiferroic heterostructure consisted of piezoelectric lithium niobate thin film and magnetic nickel thin film. We investigated the attenuation characteristics of the Lamb wave delay line, corresponding to the horizontal shear mode at this operating frequency. Our experimental findings reveal that the minimum loss within the passband of the delay line can be dynamically adjusted, achieving a maximum attenuation of 1.2 dB by modulating the magnitude and orientation of an external magnetic field. This demonstrates the capability to actively control the insertion loss (IL) in acoustic thin-film lithium niobate delay line with magnetic layers, offering potential applications for tunable acoustic filters, delay elements, and sensors.