Exploiting microstructure and symmetry in new ferroelectric materials
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Authors
Florio, Fred
Issue Date
2020-12
Type
Electronic thesis
Thesis
Thesis
Language
ENG
Keywords
Physics
Alternative Title
Abstract
Ferroelectric materials exhibit naturally occurring electronic polarization states, inspiring a wide array of potential use and function in technology. Charge separation from internal fields and the bulk photovoltaic effect are promising properties for photo-current generation, and control over the orientation of ferroelectric polarization allows for non-volatile memory storage. Coupling ferroelectricity to other properties of symmetry, as in multiferroics, provides an external knob which can be used to tune such material properties as the crystal structure, band gap, and spin via the electric field; great for sensor and spintronic applications. Real-world application of ferroelectric materials is hindered however by their insulating nature; where larger band-gaps discourage photo-absorption. Semiconducting materials whichmaintain ferroelectricity are therefore highly desired.
In this work I present research done on the ferroelectric materials Silver-Bismuthate (Ag2BiO3) and Cyclohexylethylamine-Triiodo-Plumbate ([CYHEA]PbI3). In addition to first principles calculations, a phase field model was developed and used to simulate larger scale effects of microstructure such as domain formation and hysteresis. [CYHEA]PbI3 is a new class of chiral-ferroelectric, akin to a multiferroic in how it couples broken symmetry
in a single material. Coupling of chirality and ferroelectricity could lead to properties such as selective domain switching or optical force generation, and could find use in spintronic applications. Ag2BiO3 represents a charge-disproportionate ferroelectric, a class of materials which shows promise in photovoltaic applications. Of particular interest with this material
is the presence of a Weyl semimetallic state, which is shown here to possibly be stabilized in a polar domain interface.
Description
December 2020
School of Science
School of Science
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY