Physics of polymeric ferroic devices

Abstract

Functional polymers are macromolecules with unique and sometimes combined physical For example, poly vinylidene fluoride-co-trifluoroethylene, P(VDF-TrFE), is a well-known copolymer that is nearly a perfect insulator but also possesses piezoelectricity, a bidirectional property. Upon applying an exerted mechanical stress, electric charges with opposite polarity poles. Similarly, applying a time-variant electric potential difference induces mechanical structure of the material. P(VDF-TrFE) is also ferroelectric and belongs to a sub-category of materials that can retain their electric polarizations even after removal of the applied field. Consequently, P(VDF-TrFE) has been envisioned for energy harvesting, information multiferroic applications. In the first three chapters of this thesis, we demonstrate a proof-of-concept single transistor memory element using graphene as the semiconductor channel of a field-effect transistor P(VDF-TrFE) is used as the ferroelectric gate insulator. Besides the details of reproducible fabrication, an experimentally validated device model is presented that can be used for memory elements based on ferroelectric graphene field-effect transistors for information neuromorphic applications. The model serves as the basis for understanding of the transistors. In the remaining chapters, voltage generation in piezoelectric P(VDF-TrFE) films is finite-element analysis method, we investigate some strategies to improve the power output piezoelectric layers made of P(VDF-TrFE). Porosity is suggested and experimentally procedure for improving the voltage output in piezoelectric layers. The findings can be polymer-based multiferroic composites systems to boost their magnetoelectric coupling coefficients. Finally, the thesis demonstrates multiferroic capacitors based on nanocomposite thin-films and magnetic nanoparticles. For the first time, the theory related to magnetoelectric measurements of multiferroics using a lock-in technique is presented and the internal method is experimentally validated. Finally, through experimental investigation and finite modelling, a detailed study of the polymer-based multiferroic thin-films is presented and extensively.