Dirty limit scattering behind the decreased anisotropy of doped YBa2Cu3O7−δthin films

Malmivirta, Mika; Palonen, Heikki; Inkinen, Sampo; Yao, Lide; Tikkanen, J.; Jha, Rajveer; Awana, V. P. S.; Dijken, Sebastiaan van; Paturi, P.

doi:10.1088/0953-8984/28/17/175702

Cited by 9 publications

(13 citation statements)

References 30 publications

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“…We underline that this effect, if present, is independent on the pinning that can be produced: as an example, a negligible effect on the anisotropy, indicating negligible change in band structure, can however be accompanied by a strong directional pinning, like it was found in YBCO with BZO nanorods [30] and with nanoparticles [26]. However, in some films grown by PLD with different nanoparticles, a significant reduction of the anisotropy was reported [27,29,31], accompanied by an increase of H c2 , although in different films the increase of H c2 did not affect the anisotropy [28]. It is then interesting to investigate the anisotropy of YBCO with different nanostructuring, such as nanoparticles and nanorods.…”

Section: H Qsupporting

confidence: 52%

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa₂Cu₃O_7−δ from microwave measurements

Pompeo

Alimenti

Torokhtii

et al. 2020

Supercond. Sci. Technol.

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Anisotropy is an intrinsic factor that dictates the magnetic properties of YBa 2 Cu 3 O 7−δ , thus with great impact for many applications. Artificial pinning centres are often introduced in an attempt to mitigate its effect, resulting in less anisotropic electrical and magnetic properties. However, the nanoengineering of the superconductor makes the quantification of the anisotropy itself uncertain: the intrinsic anisotropy due to the layered structure, quantified by the anisotropy factor γ, mixes up with the additional anisotropy due to pinning. As a consequence, there is no consensus on the experimental anisotropy factor γ that can result in YBa 2 Cu 3 O 7−δ when directional (twin planes, nanorods) or isotropic defects are present. We present here measurements of the magnetic field and angular dependent surface impedance in very different nanostructured YBa 2 Cu 3 O 7−δ films, grown by chemical route and by pulsed laser deposition, with different kind of defects (nanorods, twin planes, nanoparticles). We show that the surface impedance measurements are able to disentangle the intrinsic anisotropy from the directional pinning anisotropy, thanks to the possibility to extract the true anisotropic flux-flow resistivity and by correctly exploiting the angular scaling. We find in all films that the intrinsic anisotropy γ = 5.3 ± 0.7. By contrast, the pinning anisotropy determines a much complex, feature-rich and nonuniversal, sampledependent angular landscape.

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Section: H Qsupporting

confidence: 52%

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa₂Cu₃O_7−δ from microwave measurements

Pompeo

Alimenti

Torokhtii

et al. 2020

Supercond. Sci. Technol.

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“…The origin of this reduction in γ eff by the addition of nanoparticles has been associated to isotropic nanostrain and a novel depairing mechanism related to tensile strain fields in defects formed around the nanoparticles (especially in CSD-grown films) 37,38,74 . Other authors have also considered the contribution of geometrical effects for sufficiently small 75 , dirty-limit scattering and a change in coherence length anisotropy (discussed especially for PLDgrown films) 76 .…”

Section: 3mentioning

confidence: 99%

Epitaxial superconducting GdBa₂Cu₃O_7−δ/Gd₂O₃ nanocomposite thin films from advanced low-fluorine solutions

Cayado

Mundet

Eloussifi

et al. 2017

Supercond. Sci. Technol.

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We have employed the CSD method to synthesize GdBCO and GdBCO-Gd 2 O 3 nanocomposite 250-300 nm thin films. For this we have designed a new Low-Fluorine (LF) solution never used before in the synthesis of GdBCO thin films that allow to reduce the HF release by 80% and increasing the reproducibility of the pyrolysis process. The growth of these thin films required the design of a new thermal process what we called "Flash-Heating" in which the heating rate is extremely fast (~600 ºC/min). The structure and the superconducting properties of the pristine GdBCO films are excellent showing a (00l) epitaxial orientation of the GdBCO grains and T c values that reach 92.8 K which means and enhancement of more than 1 K with respect to the standard YBCO films. The calculated J c inside the grains ( ) present also remarkable values: (5 K) ~ 40 MA/cm 2 and (77 K) ~ 3.3 MA/cm 2 . Finally, the GdBCO-Gd 2 O 3 nanocomposites films, with a 20% mol of Gd 2 O 3 , exhibit superior superconducting properties and pinning performances with respect to the GdBCO pristine films.

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“…However, the group of Paturi has reported raised values of H c2 (T) and a decrease of the intrinsic angular anisotropy to γ≈3 for PLD-grown YBCO thin-films including a small 4-8%wt. of BaCeO 3 (BCO) 19 or BZO 20,21 nanoparticles. In these works the effects of the NPs on γ eff were not discussed.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic anisotropy versus effective pinning anisotropy in YBa2Cu3O7 thin films and nanocomposites

et al. 2019

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The intrinsic and effective anisotropies, both in the liquid and solid vortex regimes, of YBa 2 Cu 3 O 7 pristine and nanocomposite thin-films have been investigated. Angular resistivity measurements under varying fields and temperatures were performed to characterize the intrinsic vs. effective anisotropy of samples in the regime of longrange vortex displacements. The effective anisotropy γ eff was determined from the scaling of the irreversibility line, applying Blatter approach developed for uniaxial anisotropic superconductors. Resistive measurements in flux-flow were utilized, in addition to H c2 measurements in ultra-high-fields, to determine the intrinsic anisotropy mass γ, enabling the study of a large number of samples with varied nanoparticle compositions. In order to access the intrinsic anisotropy in the vortex solid phase, complex impedance measurements at high microwave frequencies were performed, allowing us to access the flux-flow intrinsic anisotropy in the regime of very-short vortex oscillations within the pinning potential wells. Results show that while the effective anisotropy γ eff decays as the nanoparticlesinduced nanostrain in the YBCO films increases, the intrinsic anisotropy γ (determined both in dc and at microwave frequency) remains unaltered.

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Dirty limit scattering behind the decreased anisotropy of doped YBa₂Cu₃O_7−δthin films

Cited by 9 publications

References 30 publications

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa₂Cu₃O_7−δ from microwave measurements

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa₂Cu₃O_7−δ from microwave measurements

Epitaxial superconducting GdBa₂Cu₃O_7−δ/Gd₂O₃ nanocomposite thin films from advanced low-fluorine solutions

Intrinsic anisotropy versus effective pinning anisotropy in YBa2Cu3O7 thin films and nanocomposites

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Dirty limit scattering behind the decreased anisotropy of doped YBa2Cu3O7−δthin films

Cited by 9 publications

References 30 publications

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa2Cu3O7−δ from microwave measurements

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa2Cu3O7−δ from microwave measurements

Epitaxial superconducting GdBa2Cu3O7−δ /Gd2O3 nanocomposite thin films from advanced low-fluorine solutions

Intrinsic anisotropy versus effective pinning anisotropy in YBa2Cu3O7 thin films and nanocomposites

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Dirty limit scattering behind the decreased anisotropy of doped YBa₂Cu₃O_7−δthin films

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa₂Cu₃O_7−δ from microwave measurements

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa₂Cu₃O_7−δ from microwave measurements

Epitaxial superconducting GdBa₂Cu₃O_7−δ/Gd₂O₃ nanocomposite thin films from advanced low-fluorine solutions