Room temperature magnetic field sensing using the magneto-electric effect in single phase hexaferrite thin films

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This thesis explores potential applications of the ME effect observed in SrCo2Ti2Fe8O19 M-type hexaferrite thin films deposited using the Pulsed Laser Deposition (PLD) method. 1. This thesis investigates the physical and static magnetic properties of the ME thin films that were deposited on silicon substrates in a CMOS-compatible approach. We also studied different methods for reducing the voltage required to induce the ME effect at room temperature - a feature that still remains elusive in ME composites. 2. This thesis proposes an experimental setup for establishing the coupling phenomenon between the ME film and an inductive spiral coil separated by an air gap. We also performed a quantitative analysis of the contribution of signal frequency and amplitude in explaining the appearance of different peaks in the output spectra. In addition, the results from the proposed electrical circuit model were consistent with the experimental results, thereby enabling future integration of ME technology into existing circuit simulators. 3. In addition, this thesis investigates a method for detecting both DC and low frequency AC magnetic fields using ME thin films. The proposed sensors were designed to exhibit a good linear operating range while consuming only a small amount of power and occupying a relatively small chip area. In addition, we introduced the design and experimental implementation of bi-directional ME sensors that can determine both magnitude and direction of an incident magnetic field as an alternative to portable field sensors such as fluxgate magnetometers. Our research focused on modeling, fabrication, testing and evaluating ME-based sensors in terms of their detection range, noise performance, direction sensing capabilities as well as compatibility with existing CMOS technologies. 4. Finally, this thesis contributes to the development of a comprehensive PSPICE model for magnetic field sensors based on the ME thin film technology. This model also takes into account the reduction in field strength as a function of the distance between the ME sensor and the magnetic field source. The proposed model was shown to be capable of predicting the experimental results within 19% in the worst case.