Temperature Dependent Magneto-Acoustic Interactions in Multiferroic Heterostructure Devices

Multiferroic heterostructures offer a rich platform for studying coupled physics. In particular, magnetostrictive devices have recently gained interest for applications in tunable RF technologies. For example, surface acoustic waves (SAWs) propagating in a piezoelectric material can couple to an adjacent ferromagnetic film, resulting in magnetization dynamics. While significant work has focused on room-temperature operation of these devices, temperature dependence is largely unexplored.

Here we examine temperature dependent behavior of both SAW propagation and acoustically driven spin wave resonance (ADSWR) in heterostructure devices. Beginning with YZ-cut LiNbO₃ substrates, we use photolithography to pattern interdigitated transducers (IDTs) which generate SAWs. We then deposit thin film magnetostrictive magnets (Ni, FeGaB) between IDT pairs and examine the microwave transmission (eg. S₂₁). Sweeping the field magnitude and direction in the film plane reveals a complex absorption map which correlates to matching the magnetic resonance with the SAW frequency and direction. We will discuss the role that temperature, which affects the piezoelectricity and magnetism differently, and magnetic material, which affects anisotropy and magnetostriction, play on these interactions.