Regensburg 2022 – scientific programme

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MA: Fachverband Magnetismus

MA 9: INNOMAG e.V. Prizes 2022 (Diplom-/Master and Ph.D. Thesis)

MA 9.3: Talk

Monday, September 5, 2022, 15:40–16:05, H43

ΔE-Effect Magnetic Field Sensors — •Benjamin Spetzler, Elizaveta Golubeva, Patrick Wiegand, Robert Rieger, Jeffrey McCord, and Franz Faupel — Kiel University, Kiel, Germany

Many conceivable biomedical and diagnostic applications require the detection of small-amplitude and low-frequency magnetic fields. Against this background, we investigate a magnetometer concept based on the magnetoelastic ΔE effect. The ΔE effect causes the resonance frequency of a magnetoelastic resonator to detune in the presence of a magnetic field, which can be read out electrically with an additional piezoelectric phase. Various microelectromechanical resonators are experimentally analyzed in terms of the ΔE effect and signal-and-noise response, and models are developed and extended where necessary to identify current limitations. Although a large ΔE effect is confirmed in the shear modulus, the sensitivity of classical cantilever resonators does not benefit from this effect. An approach utilizing surface acoustic shear waves provides a solution and can detect small signals over a large bandwidth. Comprehensive analyses of the quality factor and piezoelectric material parameters indicate methods to increase sensitivity and signal-to-noise ratio significantly. The latter is currently limited by the loss of the magnetic material. First exchange-biased ΔE-effect sensors pave the way for compact setups and arrays with a large number of sensor elements. The insights gained lead to a new resonator and processing concept that can circumvent several previous limitations with prospects for sensor improvements in the future.