Surface Acoustic Wave/Spin Wave Coupling Behaviour of ScAlN/SI Based SAW Devices at Cryogenic Temperatures

This work develops for the first time an experimental analysis on the coupling of surface acoustic waves (SAW) with spin waves (SW) at low temperatures. The analysis is performed on a SAW device manufactured on the emerging high performance piezoelectric Sc<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.3</inf>Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.7</inf>N/Si layered structure with a Ni/Au thin magnetostrictive layer between its interdigitated transducers (IDT). Both Rayleigh (R) and Sezawa (S) modes are analyzed. When the temperature changes from 293 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{K}$</tex> to 30 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{K}$</tex>, we observe, for both propagation modes, a decrease in the energy transfer from the SAW to the SW and an increase in the resonance magnetic field strength. This opens new application fields such as quantum computing, where low temperature operation is very important.