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Huijbregtse, J.M.; Dam, B.; Geest, R.C.F. van der; Klaassen, F.M.; Elberse, R.; Rector, J.H.; Griessen, R.

doi:10.1103/physrevb.62.1338

Cited by 94 publications

(61 citation statements)

References 56 publications

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“…16 The dislocation densities calculated from the mean distances are 450 and 920 m 2 , which are somewhat larger than what was observed with the etching method. 31 The densities are still lower than those measured by TEM for films on MgO. 20 In the J c of Eq.…”

Section: A Pinning In Undoped Ybco Filmsmentioning

confidence: 85%

“…Pure YBCO films contain varying amounts of film penetrating dislocations, 8,24 which are not randomly situated. Instead the distribution is random only at long distances.…”

Section: Pinning By Columnar Defectsmentioning

confidence: 99%

“…The overall effect of the twin plane system on J c depends on the microstructure of the twin system, 6 but in thin films the twin density is high and "dead-end" twins are abundant. The other obvious columnar pinning sites are the threading dislocations on growth island boundaries, 7,8 but also the twin boundaries are situated there. 9 The pointlike pinning sites dominating in detwinned single crystals are not nearly as effective as the columnar pinning sites, so they are not taken into account in this paper.…”

Section: Introductionmentioning

confidence: 99%

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Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Paturi

Irjala

Huhtinen

et al. 2009

Journal of Applied Physics

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A simple model based on distributions of twin boundaries, dislocations, and BaZrO 3 nanorods is presented to describe the J c properties of undoped and BaZrO 3 ͑BZO͒-doped YBa 2 Cu 3 O x thin films. The model accurately describes the shape of J c ͑B , T͒ curves of the films, when the pinning site distributions are taken from distributions of twin spacings and BZO nanorods from transmission electron microscope images. Thus, assuming that the model can be used for prediction of the J c properties, we conclude that for enhancement of undoped films more crystalline defects are needed and for doped films a dopant that would create slightly larger rods would be optimal.

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Section: A Pinning In Undoped Ybco Filmsmentioning

confidence: 85%

“…Pure YBCO films contain varying amounts of film penetrating dislocations, 8,24 which are not randomly situated. Instead the distribution is random only at long distances.…”

Section: Pinning By Columnar Defectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Paturi

Irjala

Huhtinen

et al. 2009

Journal of Applied Physics

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“…In terms of dimensionality, dislocations are nearly ideal for pinning magnetic flux lines. However, the density of dislocations is dominated by the growth island size and their spacing is estimated to be rather large (~100 nm-~500 nm) [3,5]. To increase dislocation density, an obvious way would be to decrease the island size which the dislocations bound [6], e.g.…”

mentioning

confidence: 99%

Strongly enhanced current densities in superconducting coated conductors of YBa₂Cu₃O_7−x + BaZrO₃

MacManus‐Driscoll

FOLTYN²,

Jia³

et al. 2010

Materials for Sustainable Energy

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There are numerous potential applications for superconducting tapes, based on YBa 2 Cu 3 O 7-x (YBCO) films coated onto metallic substrates [1]. A long established goal of more than 15 years has been to understand the magnetic flux pinning mechanisms which allow films to maintain high current densities out to high magnetic fields [2]. In fact, films carry 1-2 orders of magnitude higher current densities than any other form of the material [3]. For this reason, the idea of further improving pinning has received little attention. Now that commercialisation of conductors is much closer, for both better performance and lower fabrication costs, an important goal is to achieve enhanced pinning in a practical way. In this work, we demonstrate a simple and industrially scaleable route which yields a 1.5 to 5-fold improvement in the in-field current densities of already-high-quality conductors.The sources of enhanced pinning in vapour-grown YBCO films are the natural point, line and volume imperfections, probably the most significant of these being the dislocations perpendicular to the substrate plane of film [4]. In terms of dimensionality, dislocations are nearly ideal for pinning magnetic flux lines. However, the density of dislocations is dominated by the growth island size and their spacing is estimated to be rather large (~100 nm-~500 nm) [3,5]. To increase dislocation density, an obvious way would be to decrease the island size which the dislocations bound [6], e.g. by reducing growth temperature, but this is non-trivial because the crystalline quality of the film would be compromised.Heavy ion irradiation has been shown to reduce vortex mobility [7,8] but it is impractical for treatment of coated conductors. Other work involving growth of films on mis-cut single crystal substrates has demonstrated that introduction of columnar growth defects improves J c (77K) by up to 50%, but only at a particular field orientation and magnitude [9]. Other ideas for improving pinning are introduction of defects by multi-layering or addition of particles on the substrate surface [5,10]. Using these methods some improvements appear possible in thin films on single crystal substrates.In this work, prompted by our earlier report that suggested the possibility of enhanced pinning in the presence of epitaxial second phases [11], we study BaZrO 3 additions to YBCO. The main reasons for the choice of BaZrO 3 are a) while it can grow heteroepitaxially with YBCO it has a large lattice mismatch (~ 9%) so strain between the 2 phases could introduce defects for enhanced pinning, b) it is a high melting temperature phase and so growth kinetics should be slow, leading to small particles, and c) Zr does not substitute in the YBCO structure [12]. Indeed, single crystals of YBCO are often grown in BaZrO 3 -coated crucibles [13]. BaZrO 3 has also been previously investigated as a pinning centre in bulk, melt processed YBCO [14,15]. However, it was found that the BaZrO 3 agglomerated at the growth fronts of the grains, and, because of heteroepitaxi...

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“…The best possible natural pinning centres in YBCO thin films are edge and screw dislocations, in particular for the fields applied parallel to these dislocations 27,61,75 . These dislocations are formed in the out-of-plane direction during pulsed laser deposition of the films 28,61,65,75,76 as a result of the YBCO/STO crystal lattice misfit. In Fig.…”

Section: B Ybco Thin Filmsmentioning

confidence: 99%

Significant tunability of thin film functionalities enabled by manipulating magnetic and structural nano-domains

Golovchanskiy

Pan

Fedoseev

et al. 2014

Applied Surface Science

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The influence of laser frequency on the structure and physical properties of thin films grown by pulsed laser deposition has been studied. Different types of thin films, hard ferromagnetic FePt L10 and quasi-single crystal superconducting YBa2Cu3O7 (YBCO), have been used for demonstration of the effect. Significant structural modifications have been obtained for the films with similar thicknesses. These modifications are shown to dramatically control their corresponding properties, providing an instrumental ability for tuning the practical characteristics of the films by changing the laser frequency of their deposition. In particular, 20-fold increase of coercive field and modification of demagnetization mechanism are obtained for FePt films by varying the frequency from 1 Hz to 6 Hz. Over a similar frequency range, a strong dependence on the laser frequency is discovered for the YBCO films for the critical current density behavior as a function of the applied magnetic field [ Jc(Ba)] with the unexpected reversal of Jc(Ba) curves with temperature. The mechanisms of structure modifications and corresponding property variations are proposed. The influence of laser frequency on the structure and physical properties of thin films grown by pulsed laser deposition has been studied. Different types of thin films, hard ferromagnetic FePt L10 and quasi-single crystal superconducting YBa2Cu3O7 (YBCO), have been used for demonstration of the effect. Significant structural modifications have been obtained for the films with similar thicknesses. These modifications are shown to dramatically control their corresponding properties, providing an instrumental ability for tuning the practical characteristics of the films by changing the laser frequency of their deposition. In particular, 20-fold increase of coercive field and modification of demagnetization mechanism are obtained for FePt films by varying the frequency from 1 Hz to 6 Hz. Over a similar frequency range, a strong dependence on the laser frequency is discovered for the YBCO films for the critical current density behaviour as a function of the applied magnetic field [Jc(Ba)] with the unexpected reversal of Jc(Ba) curves with temperature. The mechanisms of structure modifications and corresponding property variations are proposed.

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Natural strong pinning sites in laser-ablatedYBa2Cu3O7

Cited by 94 publications

References 56 publications

Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Strongly enhanced current densities in superconducting coated conductors of YBa₂Cu₃O_7−x + BaZrO₃

Significant tunability of thin film functionalities enabled by manipulating magnetic and structural nano-domains

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Natural strong pinning sites in laser-ablatedYBa2Cu3O7

Cited by 94 publications

References 56 publications

Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Strongly enhanced current densities in superconducting coated conductors of YBa2Cu3O7−x + BaZrO3

Significant tunability of thin film functionalities enabled by manipulating magnetic and structural nano-domains

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Product

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Strongly enhanced current densities in superconducting coated conductors of YBa₂Cu₃O_7−x + BaZrO₃