Surface-Acoustic-Wave Induced Ferromagnetic Resonance in Fe Thin Films and Magnetic Field Sensing

Surface acoustic waves (SAWs) are ubiquitous in sensor technology, their main benefits being sensitivity, amenability to remote control, and no need for an embedded energy source. The authors discuss magnetic sensors based on the resonant interaction between a surface acoustic wave and the magnetization of a thin ferromagnetic layer. This interaction can be switched on and off by tiny angular variation of the magnetic field, which could be useful to remotely monitor periodic motion, such as the rotation of a shaft. Using a simple model of magnetization dynamics accounting for the properties of the layer, they describe the salient properties of the SAW versus in-plane magnetic field.