The collective flux pinning force in (Sm0.5Eu0.5)Ba2Cu3O7−δsuperconductors

Li, P J; Wang, Z H; Hu, Anming; Bai, Zhengyang; Qiu, Li; Gao, J.

doi:10.1088/0953-2048/19/8/024

Cited by 16 publications

(8 citation statements)

References 18 publications

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“…If one is willing to correlate the fit parameters with pinning mechanisms irrespective of their statistical nature, one finds the values p in the expected range for normal core pinning at point-like defects and interfaces (0.5-1) [39]. The parameter q 1 =3 is larger than the theoretical value q=2 for shear breaking as the dominant pinning mechanism, but corresponds well with similar values found for other REBCO-based thin films and may be explained by large creep effects [44], collective pinning [45], or an interplay of the vortex lattice's elastic constants C 44 and C 66 [46]. The parameter q 2 has pure statistical meaning, as explained above.…”

Section: T Growth Dependence Of the Pinning Force Densitysupporting

confidence: 81%

BaHfO₃artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films

Erbe

Hänisch

Hühne

et al. 2015

Supercond. Sci. Technol.

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Chemical solution deposition (CSD) is a promising way to realize REBa 2 Cu 3 O 7 x (REBCO; RE = rare earth (here Y, Gd))-coated conductors with high performance in applied magnetic fields. However, the preparation process contains numerous parameters which need to be tuned to achieve high-quality films. Therefore, we investigated the growth of REBCO thin films containing nanometre-scale BaHfO 3 (BHO) particles as pinning centres for magnetic flux lines, with emphasis on the influence of crystallization temperature and substrate on the microstructure and superconductivity. Conductivity, microscopy and x-ray investigations show an enhanced performance of BHO nano-composites in comparison to pristine REBCO. Further, those measurements reveal the superiority of GdBCO to YBCO e.g. by inductive critical current densities, J c , at self-field and 77 K. YBCO is outperformed by more than 1 MA cm 2 with J c values of up to 5.0 MA cm 2 for 265 nm thick layers of GdBCO(BHO) on lanthanum aluminate. Transport in-field J c measurements demonstrate high pinning force maxima of around 4 GN m 3 for YBCO(BHO) and GdBCO(BHO). However, the irreversibility fields are appreciably higher for GdBCO. The critical temperature was not significantly reduced upon BHO addition to both YBCO and GdBCO, indicating a low tendency for Hf diffusion into the REBCO matrix. Angular-dependent J c measurements show a reduction of the anisotropy in the same order of magnitude for both REBCO compounds. Theoretical models suggest that more than one sort of pinning centre is active in all CSD films.

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Section: T Growth Dependence Of the Pinning Force Densitysupporting

confidence: 81%

BaHfO₃artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films

Erbe

Hänisch

Hühne

et al. 2015

Supercond. Sci. Technol.

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“…Exponents m ′ > 0 and r ′ ≃ 3.5 (3 ≤ r ′ ≤ 4 provides better agreement with experimental data of REBCO (e.g. [14][15][16]) than r ′ = 2 predicted form the shear modulus C 66 of vortex array [17,18]) characterizes the strength of pinning force density and behavior in highfield regions. The maximum value of…”

Section: Ideal Correlated Pinningsupporting

confidence: 60%

A possible explanation for double-peak structure in strain dependence of critical current density in REBa₂Cu₃O$_{7-\delta}$ coated conductors

Okada

Misaizu

Awaji

2020

Supercond. Sci. Technol.

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REBa 2 Cu 3 O 7−δ coated conductors (REBCO-CCs; RE: rare-earth element or Y) have garnered considerable attention in high-field magnet applications. However, the twin structure existing in the ab plane of REBCO complicates the dependence of critical current density on temperature, magnetic field, and uniaxial strain: J c (T, B, ε). In particular, the mechanism for the appearance of anomalous double-peak structure in J c (T, B, ε) is unclear.In this study, to understand the complicated strain dependence of critical current density, we measured J c (77.3 K, B, ε) of REBCO-CCs with c-axis-correlated pins or with random pins as a function of in-plane uniaxial strain and magnetic field applied parallel to the c axis. In the case of (Y,Gd)BCO-CC with BaZrO 3 nanorods, we only observed a mountain-shaped response of J c (77.3 K, B, ε) under the entire magnetic field. However, GdBCO-CC without artificial pinning centers, where random pinning is dominant, exhibited a valley-shaped response at low fields and then a mountain-shaped response at high fields. These results suggest that the variation in the pinning mechanism (correlated-or random pins) plays a crucial role in the absence/presence of double-peak structure in REBCO-CCs.We developed a phenomenological model for J c (T, B, ε) in which (i) strain dependence of superconducting properties in two domains of REBCO and (ii) ideal behavior of correlated-or random pinning are considered. Consequently, we observed that the valley-shaped response of J c (T, B, ε) can be realized in the case of ideal random pinning with limited parameters, while ideal correlated pinning always exhibits a mountain-shaped response of J c (T, B, ε). Furthermore, a crossover from a valley-shaped response under low fields to a mountain-shaped response under high fields in the strain dependence of J c (T, B, ε) is qualitatively consistent with our observations. This qualitative agreement between our model and experimental data validates the efficacy of our model to provide a clear understanding of the strain dependence of J c (T, B, ε) in REBCO-CCs, including the anomalous double-peak structure.

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“…refs 46 and 47), their independence as revealed by different effective fields is unusual (one example is given by ref. 48, where, however, the high and low field regions were separately fitted using all exponents as free parameters). In our case the lack of interaction can be explained at high temperature by the specific geometry and the type of pinning centres involved.…”

Section: Discussionmentioning

confidence: 99%

Intrinsic and extrinsic pinning in NdFeAs(O,F): vortex trapping and lock-in by the layered structure

Tarantini

Iida

Hänisch

et al. 2016

Sci Rep

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Fe-based superconductors (FBS) present a large variety of compounds whose properties are affected to different extents by their crystal structures. Amongst them, the REFeAs(O,F) (RE1111, RE being a rare-earth element) is the family with the highest critical temperature Tc but also with a large anisotropy and Josephson vortices as demonstrated in the flux-flow regime in Sm1111 (Tc ∼ 55 K). Here we focus on the pinning properties of the lower-Tc Nd1111 in the flux-creep regime. We demonstrate that for H//c critical current density Jc at high temperatures is dominated by point-defect pinning centres, whereas at low temperatures surface pinning by planar defects parallel to the c-axis and vortex shearing prevail. When the field approaches the ab-planes, two different regimes are observed at low temperatures as a consequence of the transition between 3D Abrikosov and 2D Josephson vortices: one is determined by the formation of a vortex-staircase structure and one by lock-in of vortices parallel to the layers. This is the first study on FBS showing this behaviour in the full temperature, field, and angular range and demonstrating that, despite the lower Tc and anisotropy of Nd1111 with respect to Sm1111, this compound is substantially affected by intrinsic pinning generating a strong ab-peak in Jc.

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The collective flux pinning force in (Sm_0.5Eu_0.5)Ba₂Cu₃O_7−δsuperconductors

Cited by 16 publications

References 18 publications

BaHfO₃artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films

BaHfO₃artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films

A possible explanation for double-peak structure in strain dependence of critical current density in REBa₂Cu₃O$_{7-\delta}$ coated conductors

Intrinsic and extrinsic pinning in NdFeAs(O,F): vortex trapping and lock-in by the layered structure

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The collective flux pinning force in (Sm0.5Eu0.5)Ba2Cu3O7−δsuperconductors

Cited by 16 publications

References 18 publications

BaHfO3artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films

BaHfO3artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films

A possible explanation for double-peak structure in strain dependence of critical current density in REBa2Cu3O$_{7-\delta}$ coated conductors

Intrinsic and extrinsic pinning in NdFeAs(O,F): vortex trapping and lock-in by the layered structure

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The collective flux pinning force in (Sm_0.5Eu_0.5)Ba₂Cu₃O_7−δsuperconductors

BaHfO₃artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films

BaHfO₃artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films

A possible explanation for double-peak structure in strain dependence of critical current density in REBa₂Cu₃O$_{7-\delta}$ coated conductors