Physics Commons^™

Depairing Current Density In Nbtin Superconducting Films, Nahid Shayesteh Swails

Theses and Dissertations

In this work, we systematically investigate the superconducting properties of Niobium Titanium Nitride (NbTiN) superconducting films with different geometries, which at low temperature remain superconducting. NbT iN superconducting films with a few nm thickness are widely used in devices such as superconductor-insulatorsuperconductor (SIS) mixers, superconducting cavities and resonators and superconducting nanowire single-photon detectors (SNSPD). In all these applications, films of varying dimensions are required to achieve optimal performance. The initial thickness of our samples was 125 nm deposited on a silicon substrate. We change the thickness of our samples using lithography and ion milling. We measure and analyze the thickness …

Reduced Dimensionality Effects In Gd-Based Magnetocaloric Materials, Hillary Faith Belliveau

USF Tampa Graduate Theses and Dissertations

Magnetic refrigeration based on the magnetocaloric effect (MCE) is a promising alternative to conventional gas compression based cooling techniques. Understanding impacts of reduced dimensionality on the magnetocaloric response of a material such as Gadolinium (Gd) or its alloys is essential in optimizing the performance of cooling devices, which is also the overall goal of this thesis. We have determined, in the first part of the thesis, that laminate structures of pure Gd produced by magnetron sputtering have several disadvantages. The target material (pure Gd), ultra-high vacuum components, and the electrical energy it takes to run the manufacturing process are all …

The Role Of Partial Surface Charge Compensation In The Properties Of Ferroelectric And Antiferroelectric Thin Films, Elena Glazkova

USF Tampa Graduate Theses and Dissertations

Ferroelectric and antiferroelectric ultrathin films have attracted a lot of attention recently due to their remarkable properties and their potential to allow for device miniaturization in numerous applications. However, when the ferroelectric films are scaled down, it brings about an unavoidable depolarizing field. A partial surface charge compensation allows to control the residual depolarizing field and manipulate the properties of ultrathin ferroelectric films. In this dissertation we take advantage of atomistic first-principles-based simulations to expand our understanding of the role of the partial surface charge compensation in the properties of ferroelectric and antiferroelectric ultrathin films.

The application of our computational …

Characterization Of Inert Gas Rf Plasma-Treated Indium Tin Oxide Thin Films Deposited Via Pulsed Dc Magnetron Sputtering, Amber Nicole Reed

Browse all Theses and Dissertations

In this work, the effects of a post-deposition RF plasma treatment on indium tin oxide (ITO) thin films prepared with pulsed DC magnetron sputtering in argon were investigated. The parameters of the post-deposition were studied to determine what RF power and gas pressure resulted in the greatest reduction in resistivity in the films while producing the smallest increase in substrate temperature for treatments with both argon and oxygen plasmas. The as-deposited (untreated) films and the treated films were characterized using Raman spectroscopy and X-ray diffraction to determine the effects of the post-deposition treatment on the degree of film crystallization. XPS …

(E,2e) Spectroscopic Investigations Of The Spectral Momentum Densities Of Thin Carbon Films, John Robert Dennison

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An (e,2e) electron scattering spectrometer has been constructed and used for the first time to investigate the spectral momentum density of the valence bands of a solid target. This technique provides fundamental information about the electronic structure of both crystalline and amorphous solids. The three fundamental quantities, the band structure, electron density of states, and electron momentum distribution can be simultaneously derived from the measured (e,2e) cross section.

A review of single electron and (e,2e) scattering theory is given with an emphasis on scattering from solids. The effects of multiple scattering are discussed and a method of deconvoluting those effects …