Dissertations / Theses on the topic 'Physics, Low Temperature|Physics, Condensed Matter'
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Lupien, Christian. "Piezoresistive torque magnetometry at low temperature." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ37143.pdf.
Christian, Aaron Brandon. "Magnetic and Thermal Properties of Low-Dimensional Single-Crystalline Transition-Metal Antimonates and Tantalates." Thesis, Montana State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10268687.
This work contributes to the study of magnetic interactions in the low-dimensional antiferromagnets M(Sb,Ta)2O6, where M is a transition metal. By virtue of the trirutile structure, M-O-O-M chains propagate along [110] at z = 0 and [110] at z = 1/2 of the unit cell. These chains are separated along [001] by sheets of weakly-interacting diamagnetic ions. The spin-exchange coupling perpendicular to the chains is weak, permitting the low-dimensional classification. Single crystals have been grown using chemical vapor deposition and the floating zone method. Magnetization, in-field heat capacity, and high-resolution thermal expansion measurements have been performed along various axes, revealing significant anisotropy due to the peculiar magnetic structures and low dimensionality.
The Neel temperature, TN, at which long-range order occurs is found to be unstable against the application of magnetic field above 2 T. Large fields tend to lower TN of the set of moments with projections along the applied field. Moments which are aligned perpendicular to the field are significantly less affected. This can lead to the formation of a secondary peak in heat capacity when magnetic field is along either [110] or [110]. The change in heat capacity at the location of the newly formed peak means there is a change in entropy, which depends upon the direction of applied field with respect to the magnetic moments. Consequently, an anisotropic magnetocaloric effect arises due to the unique magnetic structure. The anisotropic nature of this effect has potential applications in magnetic refrigeration.
Safranski, Christopher. "Transport measurements and fabrication of superconductor-exchange spring magnet-superconductor systems." California State University, Long Beach, 2013.
Carter, Faustin Wirkus. "A transition-edge-sensor-based instrument for the measurement of individual He2* excimers in a superfluid 4He bath at 100 mK." Thesis, Yale University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10012481.
This dissertation is an account of the first calorimetric detection of individual He*2 excimers within a bath of superfluid 4He. When superfluid helium is subject to ionizing radiation, diatomic He molecules are created in both the singlet and triplet states. The singlet He molecules decay within nanoseconds, but due to a forbidden spin-flip the triplet molecules have a relatively long lifetime of 13 seconds in superfluid He. When He* 2 molecules decay, they emit a ~15 eV photon. Nearly all matter is opaque to these vacuum-UV photons, although they do propagate through liquid helium. The triplet state excimers propagate ballistically through the superfluid until they quench upon a surface; this process deposits a large amount of energy into the surface. The prospect of detecting both excimer states is the motivation for building a detector immersed directly in the superfluid bath.
The detector used in this work is a single superconducting titanium transition edge sensor (TES). The TES is mounted inside a hermetically sealed chamber at the baseplate of a dilution refrigerator. The chamber contains superfluid helium at 100 mK. Excimers are created during the relaxation of high-energy electrons, which are introduced into the superfluid bath either in situ via a sharp tungsten tip held above the field-emission voltage, or by using an external gamma-ray source to ionize He atoms. These excimers either propagate through the LHe bath and quench on a surface, or decay and emit vacuum-ultraviolet photons that can be collected by the detector.
This dissertation discusses the design, construction, and calibration of the TES-based excimer detecting instrument. It also presents the first spectra resulting from the direct detection of individual singlet and triplet helium excimers.
Alonzo-Proulx, Olivier. "Low-temperature thermal conductivity of the amorphous superconductor FexNi₁-xZr₂." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97890.
After a short review on the concepts of superconductivity, thermal conductivity and amorphous matter, we present a study of the thermal conductivity of an exotic material, the amorphous metallic superconductor Fe0.5Ni 0.5Zr2. The results indicate an unexpected dominant electonic contribution to the thermal conductivity across the superconducting transition, in accordance with an inhomogeneous sample composed of a bulk normal phase with inhomogeneous superconducting phases.
Hetel, Iulian Nicolae. "Quantum Critical Behavior In The Superfluid Density Of High-Temperature Superconducting Thin Films." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1204918571.
Brecht, Teresa Lynn. "Micromachined quantum circuits." Thesis, Yale University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10783438.
Quantum computers will potentially outperform classical computers for certain applications by employing quantum states to store and process information. However, algorithms using quantum states are prone to errors through continuous decay, posing unique challenges to engineering a quantum system with enough quantum bits and sufficient controls to solve interesting problems. A promising platform for implementing quantum computers is that of circuit quantum electrodynamics (cQED) using superconducting qubits. Here, two energy levels of a resonant circuit endowed with a Josephson junction serve as the qubit, which is coupled to a microwave-frequency electromagnetic resonator. Modern quantum circuits are reaching size and complexity that puts extreme demands on input/output connections as well as selective isolation among internal elements. Continued progress will require adapting sophisticated 3D integration and RF packaging techniques found in today's high-density classical devices to the cQED platform. This novel technology will take the form of multilayer microwave integrated quantum circuits (MMIQCs), combining the superb coherence of three-dimensional structures with the advantages of lithographic integrated circuit fabrication. Several design and fabrication techniques are essential to this new physical architecture, notably micromachining, superconducting wafer bonding, and out-of-plane qubit coupling. This thesis explores these techniques and culminates in the design, fabrication, and measurement of a two-cavity/one-qubit MMIQC featuring qubit coupling to a superconducting micromachined cavity resonator in silicon wafers. Current prototypes are extensible to larger scale MMIQCs for scalable quantum information processing.
Rao, K. Umar. "Positron interactions at low-dimensional condensed surfaces." Thesis, Royal Holloway, University of London, 1988. http://repository.royalholloway.ac.uk/items/9042f7f2-0cb6-4d26-90ff-957fe870187a/1/.
Greer, Allan J. Jr. "Low internal magnetic fields in anisotropic superconductors." W&M ScholarWorks, 1994. https://scholarworks.wm.edu/etd/1539623852.
Buckingham, David Tracy Willis. "High-Resolution Thermal Expansion and Dielectric Relaxation Measurements on H2O and D2O Ice Ih." Thesis, Montana State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10607201.
Ice Ih, formed by freezing liquid water below 273∼K at atmospheric pressure, is well-known and highly-studied, but some of its fundamental physical properties have mystified scientists since the early twentieth century. The thermal expansion is one of those properties; the low relative-resolution of past measurements has left questions regarding the structural isotropy and negative thermal expansion (NTE). Furthermore, the existence of relaxation phenomena near 100∼K, related to the residual entropy at 0∼K, may reveal itself through subtle features in the thermal expansion and, thus, warrants further investigation. Here we measure the thermal expansion of ultra-pure single crystal ice from 5–265∼K with 106 times higher relative resolution than has previously been made. The data reveal a distinct crossover to NTE below 62∼K, and a third-order transition along the crystallographic \(c\)-axis near 100∼K, as evident by an unambiguous relaxational decrease in the thermal expansion coefficient on cooling. To further understand the nature of the transition, isotopic substitution and dielectric measurements were performed.
Three properties of the dielectric relaxation in ice were probed at temperatures between 80--250∼K; the thermally stimulated depolarization (TSD) current, static electrical conductivity, and dielectric relaxation time. The dielectric data agree with relaxation-based models and provide for the determination of activation energies which identify the dielectric relaxation in ice as being dominated by Bjerrum defects below 140∼K. An anisotropy was also found in the data which revealed that molecular reorientations, in the form of propagating Bjerrum point defects, are energetically favored along the \(c\)-axis between 80--140∼K. Furthermore, a similar relaxational effect to that observed in the thermal expansion was observed in the TSD along \(c\), providing a strong correlation between dielectric relaxation and inherent thermodynamic relaxation in ice. Finally, isotopic substitution in both measurement sets indicates the transition is related the movements of hydrogen nuclei, not those of the whole molecule, and provides details about the low-temperature phonon modes. These findings paint a picture of ice as a proton-disordered crystal which undergoes a partial ordering on cooling near 100∼K but, before an ordered equilibrium state is realized, the exponentially increasing relaxation time rapidly slows the ordering and ultimately freezes-in the residual entropy, causing a continuous decrease in the thermal expansion coefficient.
Lee, Junhyun. "Novel Quantum Phase Transitions in Low-Dimensional Systems." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493318.
Physics
Roseman, Mark A. "Low temperature magnetic force microscopy studies of superconducting niobium films." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38266.
Measurements were performed using a custom built low temperature magnetic force microscope, capable of operation at temperatures ranging from 4.2 K to room temperature. Special attention has been paid to optimizing the instrumentation through a detailed study of the noise characteristics, with particular emphasis placed on achieving a large signal-to-noise ratio and corresponding high force gradient sensitivity.
Magnetic force spectroscopy data has been used to deduce the critical temperature of the superconducting samples, based upon the repulsive Meissner interaction between the magnetic tip and the sample. Images of vortices as a function of applied magnetic field demonstrate the expected linear relation between vortex density and field strength, and confirms that only single vortices, each carrying one flux quantum, are observed. Two different methods are put forward to determine the magnetic penetration depth; one using magnetic force spectroscopy, the other using constant height imaging of vortices. Images of vortices as a function of temperature demonstrate that as temperatures rise, vortices become more easily depinned during the scanning process through interactions with the magnetic field of the tip. Dissipation images of vortices suggest eddy current damping as well as vortex motion within potential wells as major sources of energy loss. Studies on a patterned niobium film show that only interstitial vortices are easily detectable by MFM, but that a strong tip influence results in significant tip induced motion of these vortices around the antidots.
Cai, Aiguo. "Study of surface flattening kinetics by low energy electron diffraction on rutile(110)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ57094.pdf.
Roumiantsev, Ilia. "Many-body effects in low-order optical nonlinearities of semiconductor quantum wells." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280383.
Rezeq, Mohammed (Moh'd). "Investigation of magnetothermal and critical current hysteresis in polycrystals of low and high T(c) type II superconductors." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6371.
Lavelle, Christopher M. "The neutronic design and performance of the Indiana University Cyclotron Facility (IUCF) Low Energy Neutron Source (LENS)." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3255512.
Title from PDF t.p. (viewed Nov. 20, 2008). Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1688. Adviser: David V. Baxter.
Roseman, Mark A. "Design and characteristics of a low-temperature atomic force microscope." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ44260.pdf.
Benzaquen, Roberto. "Photoluminescence of heavily zinc-doped gallium arsenide and gallium indium arsenide grown by low-pressure metal organic vapour phase epitaxy." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7891.
Remmes, Nicholas B. "Design of the Small Angle Neutron Scattering instrument at the Indiana University Low Energy Neutron Source : applications to the study of nanostructured materials /." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3297113.
Title from dissertation home page (viewed Sept. 30, 2008). Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1064. Adviser: David V. Baxter.
Sucharitakul, Sukrit. "2D ELECTRONIC SYSTEMS IN LAYERED SEMICONDUCTING MATERIALS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1491497351482802.
Atluri, Vasudeva Prasad 1959. "Hydrogen passivation of silicon(100) used as templates for low-temperature epitaxy and oxidation." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282650.
Christiansen, David A. "Investigation of magnetic proximity effect in ferromagnet/superconductor thin films by low temperature Magneto Optical Kerr Effect measurement." California State University, Long Beach, 2013.
Herring, Patrick Kenichi. "Low Dimensional Carbon Electronics." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11475.
Physics
Alexander-Webber, Jack A. "High magnetic field effects in low-dimensional carbon nanostructures." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:1f81947b-16d7-4ab4-ace3-6e8b192429c8.
Downs, Christopher Stephen Charles. "A route to strain-engineering electron transport in graphene." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/18897.
Taychatanapat, Thiti. "From Hopping to Ballistic Transport in Graphene-Based Electronic Devices." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10815.
Physics
Quilliam, Jeffrey. "Specific Heat of the Dilute, Dipolar-Coupled, Ising Magnet LiHoxY1-xF4." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2964.
We present heat capacity measurements on three samples at and around the concentration of the spin liquid state in zero magnetic field and in a temperature range from around 50 mK to 1 K. In contrast to previous measurements, we find no sharp features in the specific heat. The specific heat is a broad feature which is qualitatively consistent with that of a spin glass. The residual entropy as a function of x, obtained through a numerical integral of the data, however, is consistent with numerical simulations which predict a disappearance of spin glass ordering below a critical concentration of dipoles [4].
Also presented here, is ac susceptibility data on an x = 0. 45 sample which exhibits a paramagnetic to ferromagnetic transition and is found to be consistent with previous work.
McClure, Douglas. "Interferometer-Based Studies of Quantum Hall Phenomena." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10300.
Physics
Alnoor, Hatim. "Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications." Doctoral thesis, Linköpings universitet, Fysik och elektroteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-141753.
Han, Shou. "Magnetism in multiferroics and low dimensional metal-organic complexes." Thesis, Queen Mary, University of London, 2016. http://qmro.qmul.ac.uk/xmlui/handle/123456789/23198.
Casas, Brian Wesley. "Effects of disorder and low dimensionality on frozen dynamics in Ca3Co2-xMnxO6." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5657.
Yee, Michael Manchun. "Scanning Tunneling Spectroscopy of Topological Insulators and Cuprate Superconductors." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11584.
Physics
Robinson, Neil Joe. "Pairing, paramagnetism and prethermalization in strongly correlated low-dimensional quantum systems." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:167d164c-e318-49b3-83ea-69b54ec531e0.
Cardellino, Jeremy D. "Dynamics of Paramagnetic Spins: A Study of Spin Defects using Magnetic Resonance Force Microscopy." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448982765.
Qiu, Lei. "Exploring 2D Metal-Insulator Transition in p-GaAs Quantum Well with High rs." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1386337954.
Babonis, Gregory S. "Low Temperature Scanning Tunneling Microscope for Single Atom Manipulation." Ohio University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1058475483.
Brunson, Jerilyn. "Hopping Conductivity and Charge Transport in Low Density Polyethylene." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/562.
Lamouri, Abbas. "Low-energy sputtering of Teflon by oxygen ion bombardment." Case Western Reserve University School of Graduate Studies / OhioLINK, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055777824.
Diaconu, Andrei. "Ultra-low Temperature Measurements of London Penetration Depth in Iron Selenide Telluride Superconductors." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1731.
Chen, Liang-Yu. "Secondary ions sputtered by low energy ion bombardment of copper and aluminum surfaces." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058535998.
Gilbertson, Sarah Elizabeth. "Aerosol Gel production via controlled detonation of liquid precursors." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1101.
Goble, Nicholas James. "ELECTRONIC TRANSPORT AT SEMICONDUCTOR AND PEROVSKITE OXIDE INTERFACES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1454002713.
Peng, Han. "Spatial resolved electronic structure of low dimensional materials and data analysis." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:2f3503eb-93bf-48d6-b6fb-13409b925748.
Lampen, Kelley Paula J. "Low Dimensionality Effects in Complex Magnetic Oxides." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5874.
Fang, Jieping. "New Methods to Create Multielectron Bubbles in Liquid Helium." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10673.
Physics
Dargel, Piet. "Spectral functions of low-dimensional quantum systems." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-F1A3-6.
Wheeler, Elisa Maria da Silva. "Neutron scattering from low-dimensional quantum magnets." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:a8411774-4a3e-4fc3-80a1-d7e8612cba71.
Petersen, Greg M. "Anderson Localization in Low-Dimensional Systems with Long-Range Correlated Disorder." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1365762218.
Mendoza, Arenas Juan José. "Spin and energy transport in boundary-driven low-dimensional open quantum systems." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:44b89c4d-e9eb-4136-a540-c80bcabeb6f6.
Coak, Matthew. "Quantum tuning and emergent phases in charge and spin ordered materials." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/280284.