Journal ArticleDOI
Magneto-optical study of flux penetration in heavy-ion irradiated high-Tc single crystals
Th. Schuster,M. Leghissa,Michael Rudolf Koblischka,H. Kuhn,M. Kraus,Helmut Kronmüller,G. Saemann-Ischenko +6 more
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TLDR
In this article, the effect of heavy-ion irradiation on the Shubnikov phase was investigated using the high-resolution Faraday effect (HRF) technique, where the authors measured the local pinning forces and critical current densities.Abstract:
Single crystals of Bi2Sr2CaCu2O8+δ (Bi-2212) and of DyBa2Cu3O7−δ have been exposed to high-energy heavy-ion irradiation (230 MeV 58Ni-ions, 0.5 GeV 127I-ions and 1.0 GeV 208Pb-ions) with various fluences perpendicular to the sample surface and hence parallel to the c-axis of the crystals. The irradiation with Ni-ions produces spherical regions of amorphized material, whereas the iodine and lead ions create columnar defects along the paths of the projectiles in the superconductors. Using the high-resolution Faraday effect (HRF) technique, domain patterns of the Shubnikov phase are investigated. From the measured flux-density profiles, the acting local pinning forces and critical current densities are determined. To allow direct comparison of the irradiation effects under the same experimental conditions, one half of each crystal was covered by an absorber during the irradiation. Fluence-dependent measurements of the pinning forces are performed and the influence of irradiation on flux-creep effects is also investigated. All heavy-ion irradiated samples show an enhancement of the measured critical current densities up to a factor of 33 as compared to the unirradiated region of the same crystal. The effective activation energies for flux creep remain unchanged after each kind of irradiation in both types of single crystals.read more
Citations
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Journal ArticleDOI
Magneto-optical studies of current distributions in high-Tc superconductors
TL;DR: In this paper, a review of the magneto-optical imaging technique and experiments on thin films, single crystals, polycrystalline bulk ceramics, tapes and melt-textured HTS materials is presented.
Journal ArticleDOI
Magneto-optical investigations of superconductors
TL;DR: Magneto-optical investigations of the flux distributions in high-Tc superconductors are reviewed in this article, where various techniques (which are all based on the Faraday effect) are compared with each other concerning resolution and working range of temperature and external magnetic field.
Journal ArticleDOI
Vortex pinning and creep in high-temperature superconductors with columnar defects
TL;DR: In this article, the influence of the angular dispersion (splay) of the tracks on vortex pinning and creep is discussed, and measurements of the temperature, field and defect density dependence of the persistent currents and their time relaxation in YBCO are presented.
Journal ArticleDOI
Microstructure and flux distribution in both pure and carbon-nanotube-embedded Bi2Sr2CaCu2O8+δ superconductors
Sun Li Huang,M. R. Koblischka,M. R. Koblischka,K. Fossheim,Thomas W. Ebbesen,Thomas W. Ebbesen,Tom H. Johansen +6 more
TL;DR: In this article, a magneto-optical (MO) imaging was used to investigate the flux distribution in both pure and carbon nanotubes embedded Bi 2 Sr 2 CaCu 2 O 8+ δ (Bi-2212) materials.
References
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Journal ArticleDOI
Vortex confinement by columnar defects in YBa2Cu3O7 crystals: Enhanced pinning at high fields and temperatures.
L. Civale,A. D. Marwick,Thomas K. Worthington,M. A. Kirk,James R Thompson,Lia Krusin-Elbaum,Yang Ren Sun,John R. Clem,F. Holtzberg +8 more
TL;DR: A microstructure is realized which leads to very strong high-temperature flux pinning in YBa and Cu crystals, and causes a considerable enlargement of the irreversibility region in the H-T plane.
Journal ArticleDOI
Two-dimensional vortices in a stack of thin superconducting films: A model for high-temperature superconducting multilayers
TL;DR: It is shown that Josephson coupling can be neglected in the high-temperature superconductors only under very stringent conditions.
Journal ArticleDOI
Flux creep in type-ii superconductors.
TL;DR: In this paper, a superconducting quantum interferometer coupled to a creep specimen by a super-conducting flux transformer was used to make measurements of the evanescent decay of the irreversible magnetization induced by magnetic cycling.
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Distribution of activation energies for thermally activated flux motion in high-T_{c} superconductors: An inversion scheme
C.W. Hagen,R.P. Griessen +1 more
TL;DR: Within a thermally activated flux-motion model, an exact inversion scheme is derived which makes it possible to calculate the distribution of activation energies for flux motion from experimental magnetic relaxation data.
Journal ArticleDOI
Critical state in disk-shaped superconductors.
M Däumling,David C. Larbalestier +1 more
TL;DR: The magnetic fields and currents occurring in a disk-shaped superconductor in the critical state in a self-consistent way are calculated using finite-element analysis to find that the field shielded in the center of the disk is roughly equal to {ital J}{sub {ital c}}d, where {ital d} is the thickness of the disks.