Interaction of Acoustic Waves With Spin Waves Using a GHz Operating GaN/Si SAW Device With a Ni/NiFeSi Layer Between Its IDTs

A two-port surface acoustic wave (SAW) device was developed to be used for the control and excitation via spin waves (SWs). The structure was manufactured using advanced nanolithography techniques, on GaN/Si, enabling fundamental Rayleigh interdigitated transducer (IDT) resonances in the GHz frequency range. The ferromagnetic resonance (FMR) of the magnetostrictive Ni/NiFeSi layer placed between the IDTs of the SAW device can be tuned to the SAW resonance frequency by magnetic fields. Using structures with finger and interdigit spacing of 170 and 100 nm, fundamental Rayleigh IDT resonance frequencies of 6.4 and 10.4 GHz have been obtained. Coupling of SAW to SW was demonstrated through transmission measurements at the fundamental Rayleigh frequencies in a magnetic field, H from -280 to +280 mT, at different angles ( between the SAW propagation direction and the magnetic field direction. For the 6.4-GHz resonator, a maximum decrease of about 1.2 dB occurred in S , at H =30 mT and at . Time-gated processing of the frequency domain (FD) raw data was used to remove the direct electromagnetic crosstalk and triple transit effects. Nonreciprocity associated with the coupling was analyzed for the two SAW structures. The quantitative influence of the magnetic field strength on the phase of the transmission parameters is also presented.