Log in

Relevant bibliographies by topics / Copper oxide superconductors / Dissertations / Theses

Dissertations / Theses on the topic 'Copper oxide superconductors'

To see the other types of publications on this topic, follow the link: Copper oxide superconductors.

Author: Grafiati

Published: 4 June 2021

Last updated: 1 August 2024

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Copper oxide superconductors.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Garcia-Vazquez, Valentin. "Copper oxide superconductors." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185961.

Full text

Abstract:

The properties of superconducting YBa₂Cu₃O₇₋(δ) thin films have been studied. Films have been prepared by multilayer deposition followed by ex situ furnace annealing. Deposition consists of a combination of dc triode sputtering from metallic targets of Y and Cu and thermal evaporation from a BaF₂ source. Superconducting and structural properties of the films strongly depend on the annealing conditions. Several heat treatment cycles were investigated, as well as different compositions. Best results were obtained for films deposited on (100) SrTiO₃ substrates, exhibiting T(c)(onset) as high as 92 K and zero resistance by 85 K. The second part of this dissertation examines the properties of ceramic Nd₂₋ₓCeₓCuO₄₋(δ) and Nd₁ͺ₈₅Ce₀ͺ₁₅(Cu₁₋(y)Zn(y))O₄₋(δ) bulk samples. Superconducting properties are examined as a function of x and y. Accurate (± 0.001 Å) lattice parameter calculations are performed from experimental x-ray diffraction data. Comparisons with previous zinc-doping studies in the hole superconducting material La₁ͺ₈₅Sr₀ͺ₁₅CuO₄₋(δ) are made. Theoretical implications and the question of electron-hole symmetry in the copper oxide superconductors are also discussed.

APA, Harvard, Vancouver, ISO, and other styles

2

Chen, Xiao-Dong. "Experimental studies of copper oxide superconductors /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487671108307914.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Bania, William Roger 1964. "Spray pyrolysis processing of yttrium-barium-copper-oxide and bismuth-strontium-calcium-copper-oxide superconducting thin films." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277080.

Full text

Abstract:

The purpose of this investigation was to explore the processing parameters involved in the production of thin film superconductors by spray pyrolysis processing (SPP). The present study is an attempt to optimize the many parameters in SPP. The specific parameters studied were substrate temperature, carrier gas flow rate, substrate materials, solution stoichiometry, spray rate, concentration, starting materials, and substrate to nozzle distance. The effect of these parameters on film stoichiometry and the anticipated superconducting behavior were investigated at some length. Films were routinely produced in a spray chamber designed as a part of this research. Films were analyzed by Rutherford Backscattering Spectroscopy, X-Ray Diffraction, Scanning Electron Microscopy, and Meissner effect measurements.

APA, Harvard, Vancouver, ISO, and other styles

4

Pullan, Penelope Anne. "Flux pinning in yttrium barium copper oxide superconducting thin films." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320038.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Chapman, J. P. "Synthesis and characterisation of copper oxide superconductors and related materials." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597487.

Full text

Abstract:

This thesis is concerned with the synthesis of high critical temperature (T_c) copper oxide superconductors and related materials. Details are given of a range of substituted phases based on the TBa₂Cu₃O₇ structure. Chapter 1 introduces the discovery and development of the high T_c superconductors and describes their structural features. Theoretical considerations of the methods of structure determination are presented in Chapter 2 and the experimental techniques are detailed in Chapter 3. Chapter 4 gives the results of a study into the structural properties of borate substituted phases. The upper limit (x) of boron substitution in the YSr₂Cu_3-xB_xO₇ structure was found to be ≈ 0.75. Rietveld refinement using X-ray diffraction data shows YSr₂Cu_2.25B_0.75O₇ to be orthorhombic (a = 3.8176(2)Å, b = 3.8345Å, c = 10.9708Å). An electron microscopy study of this material showed a 4B:Cu ordering, giving an a x 5b x 2c supercell, consistent with an upper limit of x ≈ 0.8. Attempts to Rietveld refine the geometry of the borate group from neutron diffraction data were unsuccessful. Exploration of several mixed T1 or Bi copper oxoborate compositions did not yield any new phases. The effects of cation substitutions and inherent disorder in T1Sr₂(Ca,Y)Cu₂O₇ based materials are described in Chapter 5. 'T1Sr₂(Ca_0.4Y_0.6)Cu₂O₇' was found, by resonant synchrotron X-ray diffraction, to be (T1_0.922(4)Cu_0.078)Sr₂(Ca_0.195(5)Y_0.805)Cu₂O₇, with the inherent cross-substitution giving an optimally doped material with an average copper oxidation state of +2.14 and T_c = 86K. A comparison of first row transition metal substituents in this structure shows Mn to be a particularly good substituent, yielding an almost phase pure material with a high T_c (97K). Chapter 6 describes attempts to make the Mn analogue of YBa₂Cu₃O₇, YBa₂Mn₃O_9-x, which led to the discovery of a new tetragonal layered Mn oxide, YBaMn₂O₅ (a = 3.9204Å, c = 7.6614Å). This material exhibits no oxygen non-stoichiometry and is a valence ordered, insulating ferrimagnet below 167K.

APA, Harvard, Vancouver, ISO, and other styles

6

Kemp, Jeremy. "Electron spectroscopy and electronic structure of first row transition metal oxides." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257736.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Manton, Stephen John. "Fabrication and characterisation of high temperature superconducting bulk YBCO." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396128.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Miller, Elizabeth Jane. "The correlation of magnetisation and microstructure in melt processed yttrium barium copper oxide." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294350.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Yang, Kaiyu. "Theoretical study of high transition temperature superconducting Cu-oxide." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37683147.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Yang, Kaiyu, and 楊開宇. "Theoretical study of high transition temperature superconducting Cu-oxide." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37683147.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Drandova, Gergana Ilieva. "NMR investigations in copper-oxide chain compounds and high-T(C) superconductors." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3031043.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Hicks, William Carl. "Rare earth erbium doped yttrium barium copper oxide superconducting domains and their magnetic properties /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/10608.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Feng, Cheng-Ning. "Transmission electron microscopy studies of the structure and planar defects of yttrium calcium copper oxide." Thesis, University of Essex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361037.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Makous, John Lawrence. "Superconductivity in molybdenum/tantalum superlattices and yttrium-barium-copper-oxide thin films." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184662.

Full text

Abstract:

The properties of sputter-deposited multilayered superconductors have been studied, including Mo/Ta metallic superlattices and thin films of YBa₂Cu₃O₇₋ₓ. The former have been prepared with the same integer number of atomic planes of Mo and Ta modulating the layered composition. In contrast to behavior observed in other metal-metal superlattices, Mo/Ta exhibits long range structural coherence and metallic resistivity behavior over the entire range of wavelengths down to the monolayer limit. The structural properties of these superlattices are used to explain an anomalous decrease in the c₄₄ elastic stiffness constant previously observed in Mo/Ta for 20 Å ≤ Λ ≤ 50 Å. Superconductivity measurements indicate "universal" T(c) versus ρ behavior in Mo/Ta, and tunneling results show that these superlattices are weakly-coupled BCS superconductors. The second part of this dissertation examines the properties of superconducting thin films of YBa₂Cu₃O₇₋ₓ prepared by dc triode sputtering from metallic targets of Y and Ba₂Cu₃. Post-depression annealing in O₂ is necessary to form the superconducting oxide. Various substrates were used, including sapphire and MgO, both with and without buffer layers of Ag, and SrTiO₃. The buffer layers are used to decrease the interaction of the substrate with the film. The best results occur with films deposited on MgO with a Ag buffer layer, exhibiting T(c) onsets as high as 90 K and zero resistance by 60 K. I find that the crystalline orientation of films deposited on (100) SrTiO₃ are influenced by the substrate, and re-annealing a sample can sometimes improve its superconducting properties. Overall, reproducibility is the biggest problem with this technique, as Ba metal is highly reactive with the environment.

APA, Harvard, Vancouver, ISO, and other styles

15

Vermeulen, Christopher. "The physics of charge transfer fluctuations in the copper oxide high temperature superconductors." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364230.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Longmore, A. "Neutron scattering and praseodymium suppression of superconductivity." Thesis, University of Oxford, 1995. http://ora.ox.ac.uk/objects/uuid:46caa612-2ff0-40ae-8cdc-898a9bb9c639.

Full text

Abstract:

PrBa₂Cu₃O₆₊_x is anomalous among the compounds which can be made by substituting different rare-earth ions for yttrium (Y) in YBa₂Cu₃O₆₊_x:it is the only compound which has the same structure as YBa₂Cu₃O₆₊_x, and yet does not superconduct. This unusual property makes it an important system to study, since the differences between the two compounds could produce theoretical insights into the mechanisms of cuprate, or high-temperature, superconductivity. This thesis describes neutron scattering investigations of the magnetic properties of PrBa₂Cu₃O₆₊_x. I have investigated the magnetic ordering in well-characterised, single-crystal samples, both with and without Al-contamination. In the data analysis, proper account is taken of the sample mosaicity and the different intrinsic peak shapes encountered. Some of the most striking new characteristics reported here are that (i), there is a clear interaction between the Pr ions and the Cu-O₂ planes, (ii), the ordered Pr moments tilt away from the c-axis (as suggested previously by Mossbauer spectroscopy), and (iii), there is two-dimensional ordering in the Al-containing crystals. I show how observed trends in the magnetic ordering, as O- and Al-contents vary, may be understood in terms of charge redistribution involving the hybridisation of the Pr ions. I have also examined the crystal field transitions of the praseodymium ion. Because of the difficulties previously encountered in measuring these in PrBa₂Cu₃O₆₊_x, I have used instead the compounds PrO₂ and Y_0.3Pr_0.7Ba₂Cu₄O₈, which contain praseodymium in a chemically similar environment. Y_0.3Pr_0.7Ba₂Cu₄O₈ shows the same broadening effects as PrBa₂Cu₃O₆₊_x; PrO₂ shows signs of mixed-valency, with temperature-dependent lifetime effects. The application of symmetry considerations and the point-charge model to the crystal field measurements is considered in some detail.

APA, Harvard, Vancouver, ISO, and other styles

17

Wong, Ho-yi Eric, and 黃灝頤. "Fabrication and characterization of epitaxial YBa2Cu3Oy thin films on double-buffered silicon substrates." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B2949073X.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Wells, Cyndi Ann. "Computational and infrared studies of the structure and behavior of spontaneously adsorbed amine reagents on the high-temperature superconductor yttrium-barium-copper oxide /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Barnes, Matthew A. "Integrating High Temperature Superconducting Yttrium Barium Copper Oxide with Silicon-on-Sapphire Electronics." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1337717493.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Roth, Don Jeremy. "Property and microstructural nonuniformity in the yttrium-barium-copper-oxide superconductor determined from electrical, magnetic, and ultrasonic measurements." Case Western Reserve University School of Graduate Studies / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=case1055361216.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Tipper, J. M., and University of Lethbridge Faculty of Arts and Science. "The effects of lattice anisotropies on the physics of copper oxide planes." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2007, 2007. http://hdl.handle.net/10133/677.

Full text

Abstract:

The class of high Tc superconductors share one common structural aspect, the existence of planes of copper and oxygen ions. These planes are thought to be the source of the superconducting behaviour. They can be represented as a two-dimensional lattice of ions, which facilitates their study using numerical models. One such model is the t − J model. In most studies utilising numerical models, the planes have been considered isotropic. However, recent analysis of cuprate structure has illustrated that this may not be representative of the copper oxide planes. A number of cuprate structures exhibit different phases in which the planes are not isotropic, such as the low temperature orthorhombic and low temperature tetragonal phases. This work will examine the effects of introducing anisotropy into the t − J model in order to understand how these phases affect the results gained from numerical studies.
x, 89 leaves : ill. ; 29 cm.

APA, Harvard, Vancouver, ISO, and other styles

22

Chen, Chen, and 陈晨. "Numerical studies of phase fluctuations in cuprate superconductors." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46482623.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Hayakawa, N., A. Ishiyama, N. Amemiya, T. Hasegawa, T. Saitoh, M. Yagi, S. Mukoyama, et al. "Development of 66 kV and 275 kV Class REBCO HTS Power Cables." IEEE, 2013. http://hdl.handle.net/2237/20737.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Kornecki, Michael. "Single fluxoid thermal smearing and the second peak in YBa₂Cu₃O₇ /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p3115563.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Xenikos, Dimitrios George. "Statics and dynamics of the mixed state in pure and aluminum-doped yttrium barium copper oxide high-temperature superconductors /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487856076412837.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Sebastian, Mary Ann Patricia. "Enhancing the Flux Pinning of High Temperature Superconducting Yttrium Barium Copper Oxide Thin Films." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1501777042774346.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Milliken, Damion Alexander. "Uranium doping of silver sheathed bismuth-strontium-calcium-copper-oxide superconducting tapes for increased critical current density through enhanced flux pinning." Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20040810.154223/index.html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Hossain, Md Masrur. "Absolute value of the magnetic penetration depth and field profile in the Meissner state of exotic superconductors Yttrium barium copper oxide and Co-doped pnictide." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43479.

Full text

Abstract:

One of the fundamental quantities of a superconductor is the magnetic penetration depth, λ, which is the characteristic length scale that a magnetic field penetrates into the surface of a superconductor while in the Meissner state. In the clean limit the absolute value of λ is directly related to the superfluid density ns via 1/λ² = μοe²ns/m∗ , where m∗ is the effective mass. Consequently, its variation as a function of temperature, doping and orientation are of central importance in testing microscopic theories of exotic superconductors. A low energy beam of spin polarized muons has recently been developed, at the Paul Scherrrer Institute, to directly measure λ in a superconductor. When a muon (μ+) decays, it emits a fast decay positron preferentially along the direction of its spin due to the parity violating decay. The time evolution of statistical average direction of the spin polarization of the muon ensemble depends sensitively on the local magnetic field which can be monitored as a function of the mean depth of implantation. In this way it is possible to measure the field profile near the surface of a superconductor and extract the magnetic penetration depth in a direct manner which is not otherwise possible with conventional bulk methods. In this thesis, accurate measurements of λ and its anisotropy (≡ λa /λb) have been made for three different oxygen (x = 6.52, 6.92 and 6.998) contents of YBa₂Cu₃O₆₊x as well as in Ba(Co₀.₀₇₄Fe₀.₉₂₆₎₂As₂. The measured values of λ and the in-plane anisotropies are considerably different from that reported in the literature, using less direct methods. The a – b anisotropy is surprisingly insensitive to x in YBa₂Cu₃O₆₊x . We observe an exponential decay of the magnetic field and corresponding supercurrent density deep inside the crystals. Small deviations from the London model are observed which indicate there is a suppression of the supercurrent density close to the surface. The measured (λ) values are also found to depart substantially from the Uemura relation Tcα 1/λ² .

APA, Harvard, Vancouver, ISO, and other styles

29

Valdez-Balderas, Daniel. "Models for inhomogeneities and thermal fluctuations in two-dimensional superconductors." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180117179.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Kim, Kwangmoo. "Topics in the theory of inhomogeneous media composite superconductors and dielectrics /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180537980.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Lappas, C. Alexandros. "Physical properties of magnetic and (super)conducting layered copper oxides." Thesis, University of Sussex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336099.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Pu, Song. "Heat transport in the high-temperature superconductor yttrium barium copper oxide." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29767.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Pu, Song 1968. "Heat transport in the high-temperature superconductor Yttrium Barium copper oxide." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27392.

Full text

Abstract:

The thermal conductivity $ kappa$ of the high-temperature superconductor $ rm YBa sb2Cu sb3O sb{7- delta}$ has been the subject of numerous investigations in recent years. Previous measurements show that $ kappa$: (1) exhibits a large peak in the superconducting state; (2) is anisotropic in the basal plane of the orthorhombic crystal structure. The main two subjects of this thesis are: (1) the origin of the peak and (2) a detailed investigation of the anisotropy.
In order to investigate the relative contribution of electrons and phonons to the heat conduction in YBCO, we have measured the thermal and electrical conductivities of high-quality twinned and detwinned crystals, with different levels of Zn-doping (from 0% to 3%). We found that the peak was rapidly suppressed by the impurities. Two scenarios are used to explain our results, attributing the effect to decrease in the carrier mean free path of either the electrons or the phonons.
As for the anisotropy between the a-axis and the b-axis, only two previous studies had previously been done. We find some new striking features: (1) a peak appears in $ kappa sb{chain}$ below 50 K, revealed as a result of our using of higher purity samples. (2) this peak is similar to that of $ kappa sb{a}$ below $T sb{c} (i.e., kappa sb{plane}),$ which we take as the evidence for the growth of superfluid density in the chains below 60 K. We discuss these results in terms of a model of single-electron tunneling between chains and planes.

APA, Harvard, Vancouver, ISO, and other styles

34

Zuev, Yuri L. "Studies of thermal phase fluctuations in severely underdoped YBCO films." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1124987327.

Full text

Abstract:

Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xvii, 109 p.; also includes graphics (some col.). Includes bibliographical references (p. 105-109). Available online via OhioLINK's ETD Center

APA, Harvard, Vancouver, ISO, and other styles

35

Komori, Sachio. "Epitaxial Growth and Superconducting Properties of 1212 Copper Oxides." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215546.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Zhang, Zailan. "Electronic structures, quasi-particle and gap dynamics in copper oxides superconductors using Time and Angle Resolved Photoemission Spectroscopy." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066126/document.

Full text

Abstract:

Les supraconducteurs à base d'oxyde de cuivre ont fait l'objet d'études approfondis mais ils restent toujours au centre de nombreux débats. Après 30 années de recherche, certaines questions scientifiques ont été éclairées, alors que d'autres restent controversées. L'évolution du paramètre d'ordre supraconducteur avec la température et le dopage en est un cas exemplaire. Dans cette thèse nous décrivons notre étude systématique de supraconducteurs à haute temperature critique par Angle Resolved PhotoEmission Spectroscopy (ARPES: Spectroscopie de photoémission résolue en angle) et par ARPES resolué en temps. On a mesuré du Bi2Sr2CaCu2O8+δ avec dopage optimale (c.a.d. montrant la Tc la plus élevé), afin d'explorer la possibilité que une photo-excitation très intense du supraconducteur crée un état avec des paires de Cooper incohérentes et sans aucune densité superfluide. La méthode expérimentale employée nous a permis de mesurer la dynamique des électrons hors équilibre et du gap supraconducteur, en fournissant des informations complémentaires à l'ARPES conventionnelle et aux mesures optiques. Nos données de ARPES résolue en temps sur Bi2Sr2CaCu2O8+δ montrent que une photo-excitation génère un effondrement du gap supraconducteur qui dépend du moment. La relaxation des quasi-particules acquiert une composante rapide à la fluence F de seuil ou le gap s'effondre complètement. La comparaison entre le F_pair et le F_phase spar spectroscopie optique THz résolue en temps suggère que il y aurait un régime de fluence ou les paires de Cooper survivent, mais ne portant plus un courant superfluide.Un autre défi majeur dans la physique des cuprates supraconducteurs à haute température critique (HTSCs) est la compréhension de l'état normale à haute température. Nous presentons aussi un étude ARPES du pseudo-gap proche du point nodale de la surface de Fermi dans le système La2-xBaxCuO4 (LBCO), qui montre un possible lien avec les modulations de densité de charge (stripes). Nos données suggerent que le gap s'ouvre en dessous de la transition LTT-LTO associé à l'apparition des modulations de charge tandis que la fonction spectrale n'est pas affecté par le modulation de la densité de spin. On observe aussi que la structure de bande dans LBCO est rénormalisé avant le "kink" à environs 70 meV. Nous corrélons cette rénormalisation en énergie et moment à l'amollissement du mode d'étirement de la liaison Cu-O
The superconductors of the copper-oxide family have been matter of extensive investigations and are still subject of fierce debates. After 30 years of research, some issues have been settled, whereas others remain controversial. The evolution of the superconducting order parameter with temperature and doping level is an exemplary case. In this thesis, we report a systematic Time resolved Angle Resolved PhotoEmission Spectroscopy (ARPES) study of the optimally doped Bi2Sr2CaCu2O8+δ to explore the possibility that an intense photoexcitation of the superconductor can generate a state with incoherent copper pairs and no superfluid density. The employed experimental methods allow us to measure the dynamics of non-equilibrium electrons and of the superconducting gap, providing complementary information to conventional ARPES and optical measurement. Our time resolved ARPES data of Bi2Sr2CaCu2O8+δ, report a momentum-dependent collapse of the superconducting gap upon photoexcitation. Interestingly, the QP relaxation develops a faster component at the threshold fluence F_pair where the gap has fully collapsed. The comparison between the F_pair and the F_phase extracted by tr-THz suggested the existence a fluence regime when the Cooper pairs have survived, but without holding superfluid current. A second major challenge in the physics of HTSCs is the poor understanding of the normal phase at high temperature. We also present the ARPES study of the near nodal pseudo-gap in La2-xBaxCuO4 (LBCO) to show a possible link with charge modulation (stripes). Our data show that the near nodal gap open below the LTT-LTO transition, which is linked to the formation of such modulations, instead of the one where spin modulations appear. The data show that the band structure of LBCO is affected by a renormalization setting in prior to the 70 meV kink. We were able to correlate this renormalization of the ARPES data to the region where the Cu-O bond-stretching mode soften, both in energy and momentum space

APA, Harvard, Vancouver, ISO, and other styles

37

Johnston, Martin David. "Current and field distribution in high temperature superconductors." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298870.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Gaidos, Gerard. "Radio-frequency induced flux lattice annealing in the electron-doped anisotropic superconductor praseodymium cerium copper oxide." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1692096881&sid=5&Fmt=2&clientId=1564&RQT=309&VName=PQD.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Zhang, Zailan. "Electronic structures, quasi-particle and gap dynamics in copper oxides superconductors using Time and Angle Resolved Photoemission Spectroscopy." Electronic Thesis or Diss., Paris 6, 2017. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2017PA066126.pdf.

Full text

Abstract:

Les supraconducteurs à base d'oxyde de cuivre ont fait l'objet d'études approfondis mais ils restent toujours au centre de nombreux débats. Après 30 années de recherche, certaines questions scientifiques ont été éclairées, alors que d'autres restent controversées. L'évolution du paramètre d'ordre supraconducteur avec la température et le dopage en est un cas exemplaire. Dans cette thèse nous décrivons notre étude systématique de supraconducteurs à haute temperature critique par Angle Resolved PhotoEmission Spectroscopy (ARPES: Spectroscopie de photoémission résolue en angle) et par ARPES resolué en temps. On a mesuré du Bi2Sr2CaCu2O8+δ avec dopage optimale (c.a.d. montrant la Tc la plus élevé), afin d'explorer la possibilité que une photo-excitation très intense du supraconducteur crée un état avec des paires de Cooper incohérentes et sans aucune densité superfluide. La méthode expérimentale employée nous a permis de mesurer la dynamique des électrons hors équilibre et du gap supraconducteur, en fournissant des informations complémentaires à l'ARPES conventionnelle et aux mesures optiques. Nos données de ARPES résolue en temps sur Bi2Sr2CaCu2O8+δ montrent que une photo-excitation génère un effondrement du gap supraconducteur qui dépend du moment. La relaxation des quasi-particules acquiert une composante rapide à la fluence F de seuil ou le gap s'effondre complètement. La comparaison entre le F_pair et le F_phase spar spectroscopie optique THz résolue en temps suggère que il y aurait un régime de fluence ou les paires de Cooper survivent, mais ne portant plus un courant superfluide.Un autre défi majeur dans la physique des cuprates supraconducteurs à haute température critique (HTSCs) est la compréhension de l'état normale à haute température. Nous presentons aussi un étude ARPES du pseudo-gap proche du point nodale de la surface de Fermi dans le système La2-xBaxCuO4 (LBCO), qui montre un possible lien avec les modulations de densité de charge (stripes). Nos données suggerent que le gap s'ouvre en dessous de la transition LTT-LTO associé à l'apparition des modulations de charge tandis que la fonction spectrale n'est pas affecté par le modulation de la densité de spin. On observe aussi que la structure de bande dans LBCO est rénormalisé avant le "kink" à environs 70 meV. Nous corrélons cette rénormalisation en énergie et moment à l'amollissement du mode d'étirement de la liaison Cu-O
The superconductors of the copper-oxide family have been matter of extensive investigations and are still subject of fierce debates. After 30 years of research, some issues have been settled, whereas others remain controversial. The evolution of the superconducting order parameter with temperature and doping level is an exemplary case. In this thesis, we report a systematic Time resolved Angle Resolved PhotoEmission Spectroscopy (ARPES) study of the optimally doped Bi2Sr2CaCu2O8+δ to explore the possibility that an intense photoexcitation of the superconductor can generate a state with incoherent copper pairs and no superfluid density. The employed experimental methods allow us to measure the dynamics of non-equilibrium electrons and of the superconducting gap, providing complementary information to conventional ARPES and optical measurement. Our time resolved ARPES data of Bi2Sr2CaCu2O8+δ, report a momentum-dependent collapse of the superconducting gap upon photoexcitation. Interestingly, the QP relaxation develops a faster component at the threshold fluence F_pair where the gap has fully collapsed. The comparison between the F_pair and the F_phase extracted by tr-THz suggested the existence a fluence regime when the Cooper pairs have survived, but without holding superfluid current. A second major challenge in the physics of HTSCs is the poor understanding of the normal phase at high temperature. We also present the ARPES study of the near nodal pseudo-gap in La2-xBaxCuO4 (LBCO) to show a possible link with charge modulation (stripes). Our data show that the near nodal gap open below the LTT-LTO transition, which is linked to the formation of such modulations, instead of the one where spin modulations appear. The data show that the band structure of LBCO is affected by a renormalization setting in prior to the 70 meV kink. We were able to correlate this renormalization of the ARPES data to the region where the Cu-O bond-stretching mode soften, both in energy and momentum space

APA, Harvard, Vancouver, ISO, and other styles

40

Rassau, Andreas Peter. "Static and dynamic phases of vortices in the high temperature superconductor YBaâ†2Cuâ†3Oâ†7â†-â†#delta#." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327259.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Bracanovic, Darko. "Ac susceptibility and resistivity studies of YBaâ†2Cuâ†3Oâ†7â†-â†#delta# high-temperature superconductors." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302027.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Noudem, Jacques Guillaume. "Texturation des céramiques supraconductrices Bi-Pb-Sr-Ca-Cu-O par combinaison des effets du champ magnétique et de la contrainte uniaxiale à haute température." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10169.

Full text

Abstract:

Les ceramiques supraconductrices des composes bi-(pb)-sr-ca-cu-o ont une capacite de transport de courant electrique a 77 k faible qui est due a la presence des porosites et a la desorientation des feuillets. Pour obtenir des densites de courant critique de transport elevees dans ces materiaux, il est necessaire de les densifier et d'induire une orientation cristallographique preferentielle. Un procede permettant de texturer par effet combine du champ magnetique et de la contrainte uniaxiale a haute temperature a ete mis au point. Le dispositif experimental permet d'appliquer une pression uniaxiale de 60 mpa sous un champ magnetique de 8 t jusqu'a une temperature de 1100c. Les echantillons elabores sont obtenus a partir des precurseurs industriels (hoechst) de la phase bi:2223. La technique de texturation par solidification sous champ magnetique s'est averee tres efficace pour obtenir des echantillons massifs polycristallins bi-(pb)-sr-ca-cu-o orientes avec l'axe-c des cristallites parallele au champ magnetique applique. Les densites de courant critiques (jc) obtenues par ce procede sont de 1450 a/cm#2 pour une densite de 5. 1 g/cm#3 (82% de la densite theorique). La texturation par fluage sous contrainte uniaxiale, a permis d'obtenir des ceramiques denses ( 6 g/cm#3), homogenes ayant des densites de courant critiques de 2500 a/cm#2. Les rubans ag/bi:2223 fournis par alcatel alsthom ont aussi ete textures avec succes par le procede de pressage a chaud. La combinaison du champ magnetique et de la contrainte uniaxiale permet d'ameliorer la texture et la densite des echantillons qui par ailleurs sont tres homogenes et possedent une bonne tenue mecanique. Les densites de courant critique de transport a 77 k atteignent 3800 a/cm#2 suivant les plans (a,b) et 1100 a/cm#2 suivant l'axe-c. Par ailleurs, nous avons mis en evidence la possibilite d'utiliser ces ceramiques texturees dans le domaine de l'electrotechnique pour limiter le courant

APA, Harvard, Vancouver, ISO, and other styles

43

Hyatt, Neil. "A study of structure-property relationships in layered copper oxides." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368293.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Byrne, Owen J. "Magneto-optical imaging of magnetic flux and calculation of current distributions in high temperature superconductors." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287296.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Balmer, B. R. "Processing studies on Bi-2212 superconducting thick films." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326142.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

McCurry, Martin Peter. "The growth and characterisation of YBaâ†2Cuâ†3Oâ†7â†-â†#â†dâ†eâ†lâ†tâ†aâ†# superconducting thin films." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287446.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Misat, Sylvain. "The vortex-related phase transition in YBCO thin films." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298077.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Duncan, Fiona Hazel. "Characterisation of superconducting Nd123 solid solutions and related phases." Thesis, University of Aberdeen, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297558.

Full text

Abstract:

The stoichiometry of the Nd_1+xBa_2-xCu₃O_7-δ solid solution has been investigated using XRD and EPMA. At 980°C in air, an essentially continuous solid solution forms with limiting compositions x_min = 0.03(1) and x_max = 0.92(2). The solid solution limits are independent of temperature over the range 300 to 1050°C, i.e. stoichiometric Nd123 does not form. Preliminary studies show that annealing in an Ar atmosphere does not affect x_min. Three structurally distinct polymorphs of Nd123ss exist - tetragonal Nd123ss, orthorhombic Nd123ss and orthorhombic Nd123ss. The stability range of each in air has been determined. Quenched samples with 0.03 ≤ x ≤ 0.6 have the tetragonal Nd123ss structure. On oxygenation, samples with 0.03 ≤ x <0.2 are orthorhombic. The orthorhombic-tetragonal phase transition is second order, both with increasing temperature and increasing x. Samples with 0.7-0.9 have the orthorhombic Nd213ss structure at all oxygen contents. Tetragonal Nd123ss is isostructural with tetragonal Y123 and orthorhombic Nd123ss is isostructural with orthorhombic Y123. Orthorhombic Nd213ss has the ideal stoichiometry Nd₂BaCu₃O_7-δ and is based on a 2a x b x 2c superstructure of the Nd123ss structure. The supercell is due to ordering of the Nd and Ba atoms, which leads to ordering of the oxygen atoms. Melting temperatures decrease with x. Two distinct regions of melting behaviour are observed; the first for 0.03 ≤ x ≤ 0.6 with a thermal minimum at x0.4, and the second for 0.7 ≤ x ≤ 0.9. Oxygen contents increase with x. Samples with larger x values have a smaller range of oxygen contents. High pressure oxygen annealing results in a constant Cu valence state of 2.35 for all values of x. Average copper valence states <2 are only obtained readily for x ≤ 0.3. T_c decreases with x and samples become non-superconducting at x0.5. For samples annealed in 1 bar O₂, 'double plateau' behaviour is observed.

APA, Harvard, Vancouver, ISO, and other styles

49

Kokkaliaris, Stylianos. "Investigation of the vortex phase diagram and dynamics in single crystalline samples of the high temperature superconductor YBaâ†2Cuâ†3Oâ†7â†-â†#delta#." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310294.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Al, Ibrahim Ali Abdullah H. "Development of CexSm1-xO2-δ as an Insulation Barrier via Chemical Deposition of Aerosol Nanoparticles for Applications for High Temperature Superconductor Power Cables in Sustainable and Renewable Energy." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/365828.

Full text

Abstract:

A significant effort has been made recently to develop second-generation HTSC tapes. In these tapes, ReBaCuO (rare-earth barium copper oxide - YBCO) thin films are produced on metallic substrates, such as textured Ni, NiW alloys and stainless steel. To prevent the interdiffusion of elements between metal substrate and superconducting material, and to match the YBCO lattice parameters with the substrate texture, different buffer layers were deposited on the substrate. In commercially available HTSC tapes, several buffer layers are typically used to obtain high-quality YBCO superconductor coatings (i.e. appropriate texture, defect-free and with a high critical current density, Jc,). Many existing HTS tape technologies use a variety of buffer layer architecture, which include YSZ, MgO, Y2O3 and CeO2 nm-thick layers and their combinations.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!