Magnetic-Field Tuning of Acoustic Propagation in Multiferroic Thin-Film Heterostructures

Magnetoelectric heterostructures integrating piezoelectric and magnetostrictive phases have emerged as a compelling material platform for investigating high-frequency magnetization dynamics and magnetoelastic coupling via acoustic wave excitation. This work presents magnetically tunable 1.015 GHz acoustic delay lines (ADLs) based on AlN/FeGaB heterostructure films, demonstrating both in-band phase and amplitude modulation capabilities. By investigating three characteristic frequency peaks (997.2 MHz, 1015.7 MHz, and 1027.5 MHz) within the device passband, it is observed that tunability tends to be enhanced near the modal peak frequencies where insertion loss is low. Under a magnetic field of 160 Oe with the acoustic wave direction perpendicular to the magnetic field (θ = 90°), the device achieves a maximum differential phase shift of 4.07° and an amplitude modulation of approximately 0.25 dB at 1015.7 MHz. Furthermore, linear phase and amplitude modulations of 3.23°/120 Oe and 0.19 dB/170 Oe are obtained at θ = 90°. These results experimentally demonstrate the feasibility of magnetic-field-engineered control in Lamb-wave acoustic delay lines, highlighting their strong potential for reconfigurable RF front-end applications.