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Articles 1 - 5 of 5
Full-Text Articles in Condensed Matter Physics
Polarization-Coupled Transport Behavior In Ultrathin Ferroelectric Heterostructures, Haidong Lu
Polarization-Coupled Transport Behavior In Ultrathin Ferroelectric Heterostructures, Haidong Lu
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
Ferroelectric polarization-coupled resistive switching behavior in ferroelectric tunnel junctions (FTJs), the tunneling electroresistance (TER) effect, is a recently predicted new phenomenon, which attracts interest due to potential application in the next generation non-volatile ferroelectric random access memories (FeRAMs). In this dissertation, we demonstrate the TER effect in FTJ devices by means of scanning probe microscopy (SPM) techniques. We have investigated several device configurations for enhancement of polarization stability and for demonstration of the resistive switching behavior: (i) using the SPM probe as a top electrode; (ii) using heterostructures with engineered interfacial atomic terminations; (iii) using metal electrodes; (iv) adding an …
Magnetic Anisotropy And Exchange In (001) Textured Fept-Based Nanostructures, Tom George
Magnetic Anisotropy And Exchange In (001) Textured Fept-Based Nanostructures, Tom George
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
Hard-magnetic L10 phase FePt has been demonstrated as a promising candidate for future nanomagnetic applications, especially magnetic recording at areal densities approaching 10 Tb/in2. Realization of FePt’s potential in recording media requires control of grain size and intergranular exchange interactions in films with high degrees of L10 order and (001) crystalline texture, including high perpendicular magnetic anisotropy. Furthermore, a write-assist mechanism must be employed to overcome the high coercivity of L10 FePt nanograins. The research described in this dissertation examines potential solutions to the aforementioned problems. Specifically, a nonepitaxial method of fabricating highly (001) textured …
Ferroelectric And Dielectric Properties Of Electroactive Oligomers And Nanocomposites, Kristin Leigh Kraemer
Ferroelectric And Dielectric Properties Of Electroactive Oligomers And Nanocomposites, Kristin Leigh Kraemer
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
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 …
Magnetic Interactions In Low-Dimensional Iron Nanostructures, Rui Zhang
Magnetic Interactions In Low-Dimensional Iron Nanostructures, Rui Zhang
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
Three systems involving low-dimensional magnetic nanostructures, namely the Kondo Effect in Isolated Cu(Fe) Clusters, Magnetization Reversal in Transition-Metal/Fe:SiO2 Thin Films, and Anisotropy and Micromagnetism of Fe/CrPt Bilayers, have been investigated to understand the magnetic interactions in iron nanostructures.
Kondo Effect in Isolated Cu(Fe) Clusters —Iron impurities were added into copper clusters embedded in an insulating matrix to ensure that the Kondo effect is strictly confined by the size of the cluster. The Kondo temperature of our naoscale system is 0.7 K, which is greatly suppressed from its bulk value of 29 K and is consistent with our theory prediction. …
Ab-Initio And Model Studies Of Spin Fluctuation Effects In Transport And Thermodynamics Of Magnetic Metals, James K. Glasbrenner
Ab-Initio And Model Studies Of Spin Fluctuation Effects In Transport And Thermodynamics Of Magnetic Metals, James K. Glasbrenner
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
Magnetic materials are vital to many devices and the manipulation of spins is central to the operation of novel devices such as spin transistors. It is important to understand the effect of spin fluctuations on such systems. In this dissertation, first-principles calculations and models further the understanding of spin fluctuation effects in the transport and thermodynamics of magnetic metals.
A simple classical spin-fluctuation Hamiltonian with a single itinerancy parameter is studied using the mean-field approximation, Monte Carlo simulations, and a generalized Onsager cavity field method. The results of these different methods are in agreement. It is found that the thermodynamics …