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Invited Lecture

Delta-E effect magnetic field sensors

Monday (17.06.2019)
13:15 - 13:45

Delta-E effect magnetic field sensors

B. Spetzler1, S. Zabel1, P. Durdaut3, A. Kittmann2, C. Müller4, J. Schmalz5, G. Schmidt6, M. Gerken5, J. McCord4, R. Knöchel3, M. Höft,3 E. Quandt2, and F. Faupel1*

1Chair for Multicomponent Materials, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany

2Chair for Inorganic Functional Materials, Kiel University

3Chair of Microwave Engineering, Kiel University

4Chair for Nanoscale Magnetic Materials, Kiel University

5Chair for Integrated Systems and Photonics, Kiel University

6Chair for Digital Signal Processing and System Theory, Kiel University


Magnetic field sensors based on the delta-E effect utilize the resonance shift of a high frequency mechanical resonator in a magnetic field, due to the change in Young’s modulus of a magnetostrictive material. Delta-E effect sensors are not affected by 1/f amplifier noise and allow broadband magnetic field measurements at low frequencies down to DC with very high dynamic range. Moreover, they are robust against microphony effects and mechanical noise. Fully integrable magnetic field sensors were achieved via replacement of magnetic by electric excitation. Since our first publication of this sensor concept in 2011 [B. Gojdka et al., Appl. Phys. Lett. 99, 223502 (2011); Nature 480, 155 (2011)], much progress has been made in understanding the complex interplay of magnetic, mechanical and electrical properties. This holds for different designs of cantilever sensors, but also for surface acoustic wave devices. Here we present a comprehensive magneto-electromechanical model that considers the interaction of magnetic, mechanical and electrical properties and show current experimental results. We discuss the delta-E effect in general and its application in diverse types of electrically excited sensors, including the most common types such as bending or bulk resonators, but also shear resonators and surface acoustic wave sensors. The model provides detailed understanding of the general limits of the sensitivity, which arise from using the delta-E effect as the sensing principle. Realistic detection limits are predicted in combination with a noise equivalent model. The simulations are validated with experimental data using different sensor designs and magnetic layers. We also discuss simultaneous operation of delta-E sensors in the delta-E mode and the direct magnetoelectric mode, e.g. for localization of the sensor.

Prof. Dr. Franz Faupel
Kiel University