Flux pinning and structural properties of high-T[tief]c superconducting thin films PDF Download

Author: Hendrik Roelof Anastasius Douwes
Publisher:
ISBN:
Category :
Languages : en
Pages : 131

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Author: Hendrik Roelof Anastasius Douwes
Publisher:
ISBN:
Category :
Languages : en
Pages : 131

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Author: Chen-Fong Tsai
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Since the discovery of the high temperature superconductor YBa2Cu3O7-[delta] (YBCO), with transition temperature (Tc = 77 K), above liquid nitrogen point in 1987 many research projects have been dedicated to enhancing the high field performance of this material for practical applications. The 2nd generation YBCO-based coated conductors are believed to be the most promising approach for commercial applications including power transmission, motors, generators, and high field magnets. With the advances of nanotechnologies, different nanoengineering methods have been demonstrated to enhance the performance of YBCO thin films, include doping with 0-dimensional (0-D) self-assembled nanoparticles, 1-dimensional (1-D) nanorods, and 2-dimensional (2-D) nanolayers. Furthermore, dopants with ferromagnetic properties are also reported to provide enhanced pinning effects by Lorentz force, especially under high-applied magnetic fields. The principle of these methods is to generate high-density defects at the heterogeneous interfaces as artificial pinning centers in an effort to improve the flux-pinning properties. The morphology and dimensions of the nanoinclusions play an important role in pining enhancement. Optimized pinning structures are likely to be located at energetically favorable vortex cores, which form a triangular lattice with dimensions close to the YBCO coherence length [xi]([xi]ab ~ 4 nm; [xi]c ~ 0.5 nm at 77 K.) However, it is challenging to achieve small dimensional nanodopants in the vapor deposited YBCO thin films. The purpose of this research is to utilize nanoengineering methods to produce optimized pinning structure in YBCO thin films. In this thesis, we systematically study the effects of different nanoinclusions on the flux-pinning properties of YBCO thin films. The 0-D ferromagnetic Fe2O3 and CoFe2O4 nanoparticles, 2-D CeO2 multilayers, and tunable vertically aligned nanocomposites (VAN) of (Fe2O3)x:(CeO2)1-x and (CoFe2O4)x:(CeO2)1-x systems are introduced into the YBCO matrix as artificial pinning centers. Results suggest that all nanoinclusions showed significant enhancement in the superconducting properties of YBCO. The ferromagnetic pinning centers dominate at high field and low temperature regimes, however, the defect pinning centers dominate at low field and high temperature regimes. The uniquely arranged VAN structure of alternating magnetic and non-magnetic nanophases, which incorporates both high defect density and tunable distribution of magnetic dopants, is believed to be an ideal solution for flux-pinning enhancement. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149478

Author: Teruo Matsushita
Publisher: Springer Nature
ISBN: 3030946398
Category : Technology & Engineering
Languages : en
Pages : 506

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This book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of superconductor, specimen size and electric field strength. Recent developments of critical current properties in various high-Tc superconductors and MgB2 are introduced. The 3rd edition has been thoroughly updated, with a new chapter on critical state model. The mechanism of irreversible properties is discussed in detail. The author provides calculations of pinning loss by the equation of motion of flux lines in the pinning potential and hysteresis loss. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. This book aims for graduate students and researchers studying superconductivity as well as engineers working in electric utility industry.

Author: Silvia Haindl
Publisher: Springer Nature
ISBN: 3030751325
Category : Technology & Engineering
Languages : en
Pages : 403

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This book provides a modern introduction to the growth, characterization, and physics of iron-based superconducting thin films. Iron pnictide and iron chalcogenide compounds have become intensively studied key materials in condensed matter physics due to their potential for high temperature superconductivity. With maximum critical temperatures of around 60 K, the new superconductors rank first after the celebrated cuprates, and the latest announcements on ultrathin films promise even more. Thin film synthesis of these superconductors began in 2008 immediately after their discovery, and this growing research area has seen remarkable progress up to the present day, especially with regard to the iron chalcogenides FeSe and FeSe1-xTex, the iron pnictide BaFe2-xCoxAs2 and iron-oxyarsenides. This essential volume provides comprehensive, state-of-the-art coverage of iron-based superconducting thin films in topical chapters with detailed information on thin film synthesis and growth, analytical film characterization, interfaces, and various aspects on physics and materials properties. Current efforts towards technological applications and functional films are outlined and discussed. The development and latest results for monolayer FeSe films are also presented. This book serves as a key reference for students, lecturers, industry engineers, and academic researchers who would like to gain an overview of this complex and growing research area.

Author: Xiao-Fen Li
Publisher:
ISBN: 9788755039483
Category :
Languages : en
Pages :

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Author: Li Chen
Publisher:
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Category :
Languages : en
Pages :

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Among the newly discovered iron-based superconductor, FeSe with the simplest structure and a transition temperature (T_c) around 8 K arouses much research interest. Although its Tc is much lower than that of the cuprates, iron chalcogenide has low anisotropy, slow decrease of the critical current density (J_c) with increasing magnetic field and high upper critical field H_c2 as well as easy composition control, which makes it a promising candidate to substitute NbSn/NbTi for high field applications. Compared with its bulk counterpart, iron-based superconductor thin film has a great potential in developing the ordered quasi-2D structure and is suitable for coating technology which has already been applied in YBa_2Cu_3O_7-x coated conductors. In this thesis, we first optimized pure FeSe thin films by different growth conditions using pulsed laser deposition (PLD) and post-annealing procedures. The microstructure properties of the films including the epitaxial quality, interface structure and secondary phase have been studied and correlated with the superconducting properties. Second, we reported our initial attempt on introducing the flux pinning centers into FeSe_0.5Te_0.5 thin films either under a controlled oxygen atmosphere or with a thin CeO_2 interlayer. The microstructure of the FeSe_0.5Te_0.5 films including the epitaxial quality, the interface structure and the secondary phase have been studied and correlated with the in-field performance of the superconducting thin films to explore the pinning properties of these nanoscale defects. Very recently, ion beam assisted deposition (IBAD) substrates have been used to grow high quality FeSe_0.5Te_0.5 tape with excellent in-field performance. The film on IBAD substrate involves multiple steps of seed layer and buffer layer deposition to establish the epitaxial growth template. Therefore a simplified and cost effective iron-based coated conductor is more desirable. Towards the practical application, we demonstrated the growth of superconducting FeSe_0.5Te_0.5 film on amorphous glass substrates for the first time. The film is highly textured with excellent superconducting properties, e.g., T_c of 10 K and J_c under self-field as high as 1.2 x 10^4 A/cm^2 at 4 K. Further optimization of the film growth with various nanoscale interlayers has been carried out. In addition the Te rich iron chalcogenide thin film with composition close to the composition with antiferromagnetic (AFM) transition has been demonstrated. Compared to the FeSe_0.5Te_0.5 which claimed to be the optimum composition from the literature report, the FeSe_0.1Te_0.9 is even more promising for the high field application with its coexistence of super high upper critical field and high critical current density. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151063

Author: Anant Narlikar
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 282

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Main headings: Flux Depinning and Current vs. Voltage Characteristics Near the Glass-Liquid Transition; Equilibrium Properties of the Mixed Phase of High-Tc Superconductors in the Presence of Pinning; Microstructure and Flux Pinning in Melt Processed (Nd,Eu,Gd)-Ba-Cu-O Superconductor; Influence of Irradiation-Induced Defects and Chemical Substitutions on the Flux Pinning in Hg-Based Single Crystals and Films; Magnetisation Discontinuities at Melting and Freezing Transitions in YBa2Cu3O7-8; Current-Induced Unbinding of Thermally Created Vortex-Antivortex Pairs in Zero Magnetic Field; Flux Creep-Flux Flow Crossover in the Presence of Disorder in High Temperature Superconductors.

Author: Niels Hessel Andersen
Publisher:
ISBN: 9788755019898
Category : High temperature superconductivity
Languages : en
Pages : 49

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Author: Zhen Yao
Publisher:
ISBN:
Category : Copper oxide superconductors
Languages : en
Pages : 234

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