Unipolar and Bipolar High-Magnetic-Field Sensors Based on Surface Acoustic Wave Resonators

Abstract

While surface acoustic wave (SAW) sensors have been used to measure temperature, pressure, strains, and low magnetic fields, the capability to measure bipolar fields and high fields is lacking. In this paper, we report magnetic surface acoustic wave sensors that consist of interdigital transducers made of a single magnetostrictive material, either Ni or TbFe 2 , or based on exchange-biased (Co=IrMn) multilayers. By controlling the ferromagnet magnetic properties, high-field sensors can be obtained with unipolar or bipolar responses. The issue of hysteretic response of the ferromagnetic material is especially addressed, and the control of the magnetic properties ensures the reversible behavior in the SAW response.

Intrinsic versus shape anisotropy in micro-structured magnetostrictive thin films for magnetic surface acoustic wave sensors

“…parallel to the easy axis of the full film (sample VIDT//EA) and the VSM test repeated. As expected from a previous study [27] and micromagnetism theory, the easy axis of magnetization remains along X+90°.…”

Multi-Mode Love-Wave SAW Magnetic-Field Sensors

“…From the phase change the magnetic-field strength can be calculated. Besides other SAW sensors [ 5 , 6 , 7 , 16 , 17 , 18 ], the delta-E effect is used for magnetic-field sensing with magnetoelectric composite resonators operating in bending or bulk modes [ 19 , 20 , 21 , 22 ]. In contrast to such sensors, the sensitivity of Love-wave magnetic-field sensors is expected to benefit from shear-resonance, as the elastic modulus change of the magnetostrictive material was reported to be largest for shear stress [ 14 ].…”

Nonreciprocal Surface Acoustic Waves in Multilayers with Magnetoelastic and Interfacial Dzyaloshinskii-Moriya Interactions

“…Rather promising recent experiments [29][30][31][32] have demonstrated that the propagation of SAWs in piezoelectric substrates can be controlled by a thin magnetic layer placed atop the substrate. The use of such heterostructures allows one to combine in a single device a highquality piezoelectric substrate (like LiNbO 3 ) and a ferromagnet with large magnetostriction (e.g., Ni).…”