Driven phonon-magnon coupling in heterogeneously integrated lithium niobate-yttrium iron garnet heterostructures

We demonstrate heterogeneous integration of 5 µm-thick Y-cut lithium niobate (LN) films onto 2 µm-thick yttrium iron garnet (YIG) on gadolinium gallium garnet (GGG) via bonding and substrate removal, producing large, void-free active areas. The LN-on-YIG heterostructure enables low-loss acoustic waveguiding while maintaining sufficient strain-mediated coupling to spin waves in the buried YIG. Using this platform, we realize surface acoustic wave delay devices and observe acoustic-driven magnetic resonance at 655 MHz, with 6.66 dB/mm absorption and a − 44°/mm phase shift. Spatially resolved laser Doppler vibrometry further shows a magnetic field-dependent long-wavelength modulation of the propagating acoustic wave, possible evidence of driven energy exchange between the acoustic and magnetic spin system. These results establish heterogeneous integration as a wafer-scalable route to low-loss magnetoacoustic devices that combine high-performance piezoelectrics with ultralow-damping magnetic insulators, eliminating the need for lattice matching.