STM observation of dislocation chains suitable for flux pinning in YBa2Cu3O7−x films

Schalk, Robert; Kundziņš, K.; Weber, H.W.; Stangl, E.; Proyer, S.; Bäuerle, D.

doi:10.1016/0921-4534(95)00698-2

Cited by 30 publications

(10 citation statements)

References 22 publications

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“…Small precipitates (Eibl andRoas 1990, Yasuda et al 2000) (for theory see also Matsushita (2000)) can significantly improve the j c in single-crystalline and melt-textured materials (see section 7.3), but the j c is still two orders of magnitude smaller compared to that for epitaxial thin films. Since in thin films surface pinning effects could be important, growth steps and growth terraces (McElfresh et al 1992, Schalk et al 1996 and the role of surface roughnesses for flux line pinning (Jooss et al 1996a(Jooss et al , 1996b have been considered. Depending on the roughness and film thickness, this effect, however, can account for ≈10-30% of the thin-film j c , only.…”

Section: Pinning Mechanism At Antiphase Boundaries In Thin Filmsmentioning

confidence: 99%

Magneto-optical studies of current distributions in high-T_csuperconductors

et al. 2002

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In the past few years magneto-optical flux imaging (MOI) has come to take an increasing role in the investigation and understanding of critical current densities in high-T c superconductors (HTS). This has been related to the significant progress in quantitative high-resolution magnetooptical imaging of flux distributions together with the model-independent determination of the corresponding current distributions. We review in this article the magneto-optical imaging technique and experiments on thin films, single crystals, polycrystalline bulk ceramics, tapes and melt-textured HTS materials and analyse systematically the properties determining the spatial distribution and the magnitude of the supercurrents. First of all, the current distribution is determined by the sample geometry. Due to the boundary conditions at the sample borders, the current distribution in samples of arbitrary shape splits up into domains of nearly uniform parallel current flow which are separated by current domain boundaries, where the current streamlines are sharply bent. Qualitatively, the current pattern is described by the Bean model; however, changes due to a spatially dependent electric field distribution which is induced by flux creep or flux flow have to be taken into account. For small magnetic fields, the Meissner phase coexists with pinned vortex phases and the geometry-dependent Meissner screening currents contribute to the observed current patterns. The influence of additional factors on the current domain patterns are systematically analysed: local magnetic field dependence of j c (B), current anisotropy, inhomogeneities and local transport properties of grain boundaries. We then continue to an overview of the current distribution and current-limiting factors of materials, relevant to technical applications like melt-textured samples, coated conductors and tapes. Finally, a selection of magneto-optical experiments which give direct insight into vortex pinning and depinning mechanisms are reviewed.

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Section: Pinning Mechanism At Antiphase Boundaries In Thin Filmsmentioning

confidence: 99%

Magneto-optical studies of current distributions in high-T_csuperconductors

et al. 2002

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“…Other linearly correlated defects could originate as linear dislocations in low-angle GB's, 27 or as dislocation chains. 28 Although all these defects are less controllable than ion-induced defects, they are effective in determining the pinning capability of these films. Figure 4 shows typical results of first and third harmonic ac susceptibility , measured in different dc fields.…”

Section: Structural and Resistive Characterizationsmentioning

confidence: 99%

Control of the critical current density inYBa2Cu3O7
Mezzetti
¹
,
Gerbaldo
²
,
Ghigo
³

et al. 1999
Phys. Rev. B
100
3
77
1
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The aim of this work is to investigate the mechanisms controlling the current-carrying capability of YBa 2 Cu 3 O 7Ϫ␦ thin films. A comparison between the magnetic properties of a film with intrinsic grainboundary defects and two films crossed by columnar defects with different densities is presented. Such properties have been studied by means of ac susceptibility measurements, resistivity measurements, and structural characterizations. The Clem and Sanchez model ͓Phys. Rev. B 50, 9355 ͑1994͔͒ is used to extract critical current values from the susceptibility data. In the virgin film, correlated grain-boundary defects were created among islands with homogeneous size, by means of the appropriate modifications in the growth process. Columnar defects were produced through 0.25-GeV Au-ion irradiation. The central issue concerns the investigation of the plateaulike features characterizing the log-log field dependence of the critical current density, the analysis of the J c temperature dependence, and of the irreversibility line. An analytical expression of J c vs B is given in order to compare the main issues with the experimental data. This model suggests that the intergrain pinning dominates in the high-current/low-temperature regime through a network of frustrated Josephson junctions, while the intragrain pinning is effective near the irreversibility line.

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“…crystalline defects, such as fine precipitates of non-superconducting phases, oxygen vacancies http://dx.doi.org/10.1016/j.nimb.2014.11.048 0168-583X/Ó 2014 Elsevier B.V. All rights reserved. [20], dislocations [21,22], columnar defects and so on, reduces the vortex energy to such an extent that vortices tend to stay pinned at the bottom of these potential energy wells. The size, shape and density of pinning sites play a crucial role in pinning mechanism and are effective when the size is of the order of vortex core for effective pinning.…”

Section: Introductionmentioning

confidence: 97%

Critical current density enhancement by ion irradiation for thick YBa2Cu3O7−δ films prepared by diffusion reaction technique

Kujur

Behera

2015

Nuclear Instruments and Methods in Physics Research Section B:

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STM observation of dislocation chains suitable for flux pinning in YBa2Cu3O7−x films

Cited by 30 publications

References 22 publications

Magneto-optical studies of current distributions in high-T_csuperconductors

Magneto-optical studies of current distributions in high-T_csuperconductors

Control of the critical current density inYBa2Cu3O7
Mezzetti
¹
,
Gerbaldo
²
,
Ghigo
³

et al. 1999
Phys. Rev. B
100
3
77
1
View full text Add to dashboard Cite

Critical current density enhancement by ion irradiation for thick YBa2Cu3O7−δ films prepared by diffusion reaction technique

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STM observation of dislocation chains suitable for flux pinning in YBa2Cu3O7−x films

Cited by 30 publications

References 22 publications

Magneto-optical studies of current distributions in high-Tcsuperconductors

Magneto-optical studies of current distributions in high-Tcsuperconductors

Control of the critical current density inYBa2Cu3O7Mezzetti1, Gerbaldo2, Ghigo3 et al. 1999Phys. Rev. B1003771View full textAdd to dashboardCite

Critical current density enhancement by ion irradiation for thick YBa2Cu3O7−δ films prepared by diffusion reaction technique

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Magneto-optical studies of current distributions in high-T_csuperconductors

Magneto-optical studies of current distributions in high-T_csuperconductors

Control of the critical current density inYBa2Cu3O7
Mezzetti
¹
,
Gerbaldo
²
,
Ghigo
³

et al. 1999
Phys. Rev. B
100
3
77
1
View full text Add to dashboard Cite