Berlin 2015 – scientific programme

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MA: Fachverband Magnetismus

MA 52: Magnetic Thin Films II

MA 52.9: Talk

Friday, March 20, 2015, 11:45–12:00, H 1012

Magnetoelectric MEMS sensors based on the ΔE-effect — Sebastian Zabel¹, Christine Kirchhof², Eckhard Quandt¹, and •Franz Faupel² — ¹Chair for Multicomponent Materials, Faculty of Engineering, Christian-Albrechts-University at Kiel, Kaiserstraße 2, D-24143 Kiel — ²Chair for Inorganic Functional Materials, Faculty of Engineering, Christian-Albrechts-University at Kiel, Kaiserstraße 2, D-24143 Kiel

We present new developments of integrated MEMS magnetic field sensors based on the ΔE-effect, which extends our previous approach [Gojdka et al., Appl. Phys. Lett. 99, 223502 (2011); Nature 480, 155 (2011)]. This effect describes a change of elastic modulus in magnetostrictive materials upon application of a magnetic field. The change of elastic modulus is measured by the change of resonance frequency of a one side clamped cantilever. The 1 x 3 mm Si cantilever is 50 μm thick and coated with a 2 μm thick piezoelectric AlN layer on the top and a 2 μm thick magnetostrictive FeCoSiB amorphous film on the bottom. The piezoelectric layer is used for excitation of the first (7.6 kHz) or second (47 kHz) resonant bending mode as well as the readout of amplitude and phase by current measurements. The sensor shows linear amplitude response from several μT down to the limit of detection at 200 pT/Hz^1/2. High resonance frequencies enable a bandwidth of 60 Hz and prevent coupling to acoustic noise. Vector field capability is achieved by anisotropy control. In order to maximize sensitivity a bias field of 0.7 mT has to be applied.Funding by the DFG is gratefully acknowledged.