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University of Nebraska - Lincoln

Ferroelectric

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

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Full-Text Articles in Physics

Ferroelectric Polarization Dependent Interface Effects, Xiaohui Liu Dec 2014

Ferroelectric Polarization Dependent Interface Effects, Xiaohui Liu

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

Utilization of the switchable spontaneous polarization of nanometer scale ferroelectric materials offers a promising avenue for future nanoelectronic devices. In this dissertation, we use density-functional calculations and phenomenological modeling to explore the effects of interface termination on thin-film heterostructures, the effects of electron doping in bulk ferroelectric materials on ferroelectric stability, and the effects of ferroelectric polarization switching on the electronic and transport properties of interfaces.

For SrRuO3/BaTiO3/SrRuO3 epitaxial heterostructures grown on SrTiO3, we find that the built-in dipole at the BaO/RuO2 terminated interface leads to a strong preference for one polarization ...


Ferroelectric And Dielectric Properties Of Electroactive Oligomers And Nanocomposites, Kristin Leigh Kraemer Aug 2013

Ferroelectric And Dielectric Properties Of Electroactive Oligomers And Nanocomposites, Kristin Leigh Kraemer

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

Polyvinylidene fluoride (PVDF) and its copolymers have been well established as ferroelectric polymers. The dielectric and ferroelectric properties for vinylidene fluoride (VDF) oligomer thin films were investigated. By synthesizing oligomers instead of long polymer chains, films with higher crystalinity can be formed and the locations of oligomers can be controlled for applications such as molecular electronics.

Evidence of ferroelectricity was observed in oligomer thin films evaporated onto room temperature substrates and by Langmuir-Blodgett (LB) deposition. Voltage and frequency dependence of the capacitance was measured. Oligomers functionalized with phosphonic acid formed self-assembled monolayers (SAM) on aluminum and mica substrates. Film thickness ...


Functional Two-Dimensional Electronic Gases At Interfaces Of Oxide Heterostructures, Yong Wang Aug 2011

Functional Two-Dimensional Electronic Gases At Interfaces Of Oxide Heterostructures, Yong Wang

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

A quasi-two dimensional electron gas (2DEG) in oxide heterostructures such as LaAlO3/SrTiO3 has unique properties that are promising for applications in all-oxide electronic devices. In this dissertation, we focus on understanding and predicting novel properties of the 2DEG by performing first-principles electronic calculations within the frame work of density-functional theory (DFT).

The effects of polarization in all-oxide heterostructures incorporating different ferroelectric constituents, such as KNbO3/ATiO3 (A = Sr, Ba, Pb), are investigated. It is found that screening charge at the interface that counteracts the depolarizing electric field in the ferroelectric material significantly changes the free ...