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Superconducting Properties and Electron Scattering Mechanisms in a Nb Film with a Single Weak-Link Excavated by Focused Ion Beam. MATERIALS 2021; 14:ma14237274. [PMID: 34885429 PMCID: PMC8658209 DOI: 10.3390/ma14237274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 11/18/2021] [Accepted: 11/20/2021] [Indexed: 11/16/2022]
Abstract
Granularity is one of the main features restricting the maximum current which a superconductor can carry without losses, persisting as an important research topic when applications are concerned. To directly observe its effects on a typical thin superconducting specimen, we have modeled the simplest possible granular system by fabricating a single artificial weak-link in the center of a high-quality Nb film using the focused ion beam technique. Then, its microstructural, magnetic, and electric properties in both normal and superconducting states were studied. AC susceptibility, DC magnetization, and magneto-transport measurements reveal well-known granularity signatures and how they negatively affect superconductivity. Moreover, we also investigate the normal state electron scattering mechanisms in the Boltzmann theory framework. The results clearly demonstrate the effect of the milling technique, giving rise to an additional quadratic-in-temperature contribution to the usual cubic-in-temperature sd band scattering for the Nb film. Finally, by analyzing samples with varying density of incorporated defects, the emergence of the additional contribution is correlated to a decrease in their critical temperature, in agreement with recent theoretical results.
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Xu A, Zhang Y, Gharahcheshmeh MH, Yao Y, Galstyan E, Abraimov D, Kametani F, Polyanskii A, Jaroszynski J, Griffin V, Majkic G, Larbalestier DC, Selvamanickam V. J e (4.2 K, 31.2 T) beyond 1 kA/mm 2 of a ~3.2 μm thick, 20 mol% Zr-added MOCVD REBCO coated conductor. Sci Rep 2017; 7:6853. [PMID: 28761173 PMCID: PMC5537340 DOI: 10.1038/s41598-017-06881-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/19/2017] [Indexed: 11/29/2022] Open
Abstract
A main challenge that significantly impedes REBa2Cu3Ox (RE = rare earth) coated conductor applications is the low engineering critical current density J e because of the low superconductor fill factor in a complicated layered structure that is crucial for REBa2Cu3Ox to carry supercurrent. Recently, we have successfully achieved engineering critical current density beyond 2.0 kA/mm2 at 4.2 K and 16 T, by growing thick REBa2Cu3Ox layer, from ∼1.0 μm up to ∼3.2 μm, as well as controlling the pinning microstructure. Such high engineering critical current density, the highest value ever observed so far, establishes the essential role of REBa2Cu3Ox coated conductors for very high field magnet applications. We attribute such excellent performance to the dense c-axis self-assembled BaZrO3 nanorods, the elimination of large misoriented grains, and the suppression of big second phase particles in this ~3.2 μm thick REBa2Cu3Ox film.
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Affiliation(s)
- A Xu
- Department of Mechanical Engineering, the Texas Center for Superconductivity, and Advanced Manufacturing Institute, University of Houston, Houston, TX, 77204, USA.
| | - Y Zhang
- Department of Mechanical Engineering, the Texas Center for Superconductivity, and Advanced Manufacturing Institute, University of Houston, Houston, TX, 77204, USA
| | - M Heydari Gharahcheshmeh
- Department of Mechanical Engineering, the Texas Center for Superconductivity, and Advanced Manufacturing Institute, University of Houston, Houston, TX, 77204, USA
| | - Y Yao
- Department of Mechanical Engineering, the Texas Center for Superconductivity, and Advanced Manufacturing Institute, University of Houston, Houston, TX, 77204, USA
| | - E Galstyan
- Department of Mechanical Engineering, the Texas Center for Superconductivity, and Advanced Manufacturing Institute, University of Houston, Houston, TX, 77204, USA
| | - D Abraimov
- Applied Superconductivity Center, National High Magnet Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - F Kametani
- Applied Superconductivity Center, National High Magnet Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - A Polyanskii
- Applied Superconductivity Center, National High Magnet Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - J Jaroszynski
- Applied Superconductivity Center, National High Magnet Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - V Griffin
- Applied Superconductivity Center, National High Magnet Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - G Majkic
- Department of Mechanical Engineering, the Texas Center for Superconductivity, and Advanced Manufacturing Institute, University of Houston, Houston, TX, 77204, USA
| | - D C Larbalestier
- Applied Superconductivity Center, National High Magnet Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - V Selvamanickam
- Department of Mechanical Engineering, the Texas Center for Superconductivity, and Advanced Manufacturing Institute, University of Houston, Houston, TX, 77204, USA
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Wells FS, Pan AV, Golovchanskiy IA, Fedoseev SA, Rozenfeld A. Observation of Transient Overcritical Currents in YBCO Thin Films using High-Speed Magneto-Optical Imaging and Dynamic Current Mapping. Sci Rep 2017; 7:40235. [PMID: 28067331 PMCID: PMC5220327 DOI: 10.1038/srep40235] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 12/02/2016] [Indexed: 11/29/2022] Open
Abstract
The dynamics of transient current distributions in superconducting YBa2Cu3O7-δ thin films were investigated during and immediately following an external field ramp, using high-speed (real-time) Magneto-Optical Imaging and calculation of dynamic current profiles. A number of qualitatively unique and previously unobserved features are seen in this novel analysis of the evolution of supercurrent during penetration. As magnetic field ramps up from zero, the dynamic current profile is characterized by strong peaks, the magnitude of which exceed the conventional critical current density (as determined from static current profiles). These peaks develop close to the sample edges, initially resembling screening currents but quickly growing in intensity as the external field increases. A discontinuity in field and current behaviour is newly observed, indicating a novel transition from increasing peak current toward relaxation behaviour. After this transition, the current peaks move toward the centre of the sample while reducing in intensity as magnetic vortices penetrate inward. This motion slows exponentially with time, with the current distribution in the long-time limit reducing to the expected Kim-model profile.
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Affiliation(s)
- Frederick S. Wells
- Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
| | - Alexey V. Pan
- Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31 Kashirskoye Shosse, 115409, Moscow, Russian Federation
| | - Igor A. Golovchanskiy
- Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
- Laboratory of Topological Quantum Phenomena in Superconducting Systems, Moscow Institute of Physics and Technology, State University, 9 Institutskiy per., Dolgoprudny, Moscow Region, 141700, Russia
- Laboratory of Superconducting Metamaterials, National University of Science and Technology MISIS, 4 Leninsky prosp., Moscow, 119049, Russia
| | - Sergey A. Fedoseev
- Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
- Center for Medical & Radiation Physics, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
| | - Anatoly Rozenfeld
- Center for Medical & Radiation Physics, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
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Larbalestier D, Gurevich A, Feldmann DM, Polyanskii A. High-Tc superconducting materials for electric power applications. Nature 2001; 414:368-77. [PMID: 11713544 DOI: 10.1038/35104654] [Citation(s) in RCA: 1027] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Large-scale superconducting electric devices for power industry depend critically on wires with high critical current densities at temperatures where cryogenic losses are tolerable. This restricts choice to two high-temperature cuprate superconductors, (Bi,Pb)2Sr2Ca2Cu3Ox and YBa2Cu3Ox, and possibly to MgB2, recently discovered to superconduct at 39 K. Crystal structure and material anisotropy place fundamental restrictions on their properties, especially in polycrystalline form. So far, power applications have followed a largely empirical, twin-track approach of conductor development and construction of prototype devices. The feasibility of superconducting power cables, magnetic energy-storage devices, transformers, fault current limiters and motors, largely using (Bi,Pb)2Sr2Ca2Cu3Ox conductor, is proven. Widespread applications now depend significantly on cost-effective resolution of fundamental materials and fabrication issues, which control the production of low-cost, high-performance conductors of these remarkable compounds.
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Affiliation(s)
- D Larbalestier
- Applied Superconductivity Center, Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706, USA.
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Pashitski AE, Gurevich A, Polyanskii AA, Larbalestier DC, Goyal A, Specht ED, Kroeger DM, DeLuca JA, Tkaczyk JE. Reconstruction of Current Flow and Imaging of Current-Limiting Defects in Polycrystalline Superconducting Films. Science 1997; 275:367-9. [PMID: 8994028 DOI: 10.1126/science.275.5298.367] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.
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Affiliation(s)
- AE Pashitski
- A. E. Pashitski, A. Gurevich, A. A. Polyanskii, D. C. Larbalestier, Applied Superconductivity Center, University of Wisconsin, Madison, WI 53706, USA. A. Goyal, E. D. Specht, D. M. Kroeger, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. J. A. DeLuca and J. E. Tkaczyk, General Electric, Schenectady, NY 12301, USA
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