Room Temperature Sensing of Magnetic Fields Using Magnetoelectric Thin Films

Abstract

We present the design, characterization, and fabrication of a sensing device for measuring low-frequency ac magnetic field variations using a single-phase magnetoelectric (ME) thin film. This ME device is fabricated using SrCo 2 Ti 2 Fe 8 O 19 and deposited on a 500-nm-thick Indium Tin Oxide layer. The ME film is then deposited on a silicon substrate using a pulsed laser deposition technique. The device size (volume) is 0.02 cm 3 , and its overall power consumption is 14 μW. We also show that this sensing device can be used to detect low ac and dc magnetic fields. In this experiment, we employ a modified Wheatstone bridge circuit as an alternative approach to detect the change in capacitance of the ME film when an external field H ext is applied. The circuit uses a combination of an ac input source and a variable capacitor to balance the bridge when the external field is zero. The experimental results demonstrate that the ME device can detect both ac and dc magnetic fields (up to 0.3 T) and is particularly sensitive for ac field sensing. Since the ME device employs a single-phase material, it is not only relatively simple to fabricate but also capable of operating at very low voltages and, therefore, suited for planar integration and compatibility with other integrated circuits.