Electrically modulated magnetoelectric sensorsWednesday (07.06.2017) 20:03 - 20:06 Förde I Part of:
A promising candidate for room temperature sensing of low frequency, low amplitude signals, e.g. from biomagnetic sources, are magnetoelectric (ME) composites. Inherent to ME composites is the exploitation of piezomagnetic properties of the magnetic material, characterized by mechanical oscillations. These oscillations as well as the ME effect undergo a strong enhancement in mechanical resonance. Thin film ME cantilevers on silicon usually yield comparably high mechanical resonance frequencies e.g. in the low kHz regime. By utilizing the sensor as a mixer using frequency conversion, the mechanical resonance amplification can be made available for the detection of magnetic signals below 100 Hz (1). Mixing in the magnetic phase by applying an off-resonance AC magnetic field as carrier signal, where the sum or difference frequency with the signal to be measured is set in such a way as to correspond to the mechanical resonance. This mixing scheme, requiring external coils, is complex to integrate into small sensor arrays. Similarly, the presented approach utilizes magnetoelastic modulation of the magnetostrictive phase by mechanical off-resonance excitation of the ME composite. In this path mixing is enabled by inverse magnetostriction, leading to a detection limit of 10 nT/sqrt(Hz) at 10 Hz without the use of an external bias field (2). In this presentation results of silicon based ME composites comprising FeCoSiB as well as PZT and AlN thin films are given. Furthermore magneto-optical and magneto-mechanical properties of modulated ME composites are discussed.