Excess of topological defects induced by confinement in vortex nanocrystals

Bolecek, Néstor René Cejas; Dolz, M. I.; Pastoriza, H.; Kończykowski, M.; Beek, C.J. van der; Kolton, Alejandro B.; Fasano, Yanina

doi:10.1103/physrevb.96.024507

Cited by 6 publications

(9 citation statements)

References 35 publications

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“…The decorated structures were frozen, at length scales of order a 0 , at temperatures at which the pinning generated by disorder sets in [27,28]. This freezing temperature is some K below the temperature at which magnetic response becomes irreversible [29]. This lenghtscale is shorter than the relevant for the hyperuniformity analysis.…”

Section: Density Fluctuations: Experimental Resultsmentioning

confidence: 99%

“…8 shows S(q) for different sample thicknesses at a fix vortex density a 0 /λ ab (T freez ) = 2 corresponding to a magnetic induction of ∼ 40 G. We considered λ ab (T freez ) ∼ 0.4 µm at the irreversibility temperature T irr (B ∼ 40 Gauss). This is the temperature at which pinning sets in, and the vortex structure is frozen at length-scales of a 0 [29]. The gray area indicates the q · λ ab (T freez ) range used for fitting α eff in our experimental S(q) data.…”

Section: Discussion and Perspectivesmentioning

confidence: 99%

“…This is a rather thin sample to be obtained just by cleaving a thicker crystal. Magnetic decoration data in 1 µm thick Bi 2 Sr 2 CaCu 2 O 8+δ micron-sized samples are available, but the field-of-view is of only a few hundred of vortices, making difficult to perform a careful hyperuniformity analysis of such vortex nanocrystals [29,32].…”

Section: Discussion and Perspectivesmentioning

confidence: 99%

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Hyperuniform vortex patterns at the surface of type-II superconductors

Rumi

Sánchez

Elías

et al. 2019

Phys. Rev. Research

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A many-particle system must posses long-range interactions in order to be hyperuniform at thermal equilibrium. Hydrodynamic arguments and numerical simulations show, nevertheless, that a three-dimensional elastic-line array with short-ranged repulsive interactions, such as vortex matter in a type-II superconductor, forms at equilibrium a class-II hyperuniform two-dimensional point pattern for any constant-z cross section. In this case, density fluctuations vanish isotropically as ∼ q α at small wave-vectors q, with α = 1. This prediction includes the solid and liquid vortex phases in the ideal clean case, and the liquid in presence of weak uncorrelated disorder. We also show that the three-dimensional Bragg glass phase is marginally hyperuniform, while the Bose glass and the liquid phase with correlated disorder are expected to be non-hyperuniform at equilibrium. Furthermore, we compare these predictions with experimental results on the large-wavelength vortex density fluctuations of magnetically decorated vortex structures nucleated in pristine, electron-irradiated and heavy-ion irradiated superconducting Bi2Sr2CaCu2O 8+δ samples in the mixed state. For most cases we find hyperuniform two-dimensional point patterns at the superconductor surface with an effective exponent α eff ≈ 1. We interpret these results in terms of a large-scale memory of the high-temperature line-liquid phase retained in the glassy dynamics when field-cooling the vortex structures into the solid phase. We also discuss the crossovers expected from the dispersivity of the elastic constants at intermediate length-scales, and the lack of hyperuniformity in the xy plane for lengths q −1 larger than the sample thickness due to finite-size effects in the z-direction. We argue these predictions may be observable and propose further imaging experiments to test them independently.arXiv:1907.00394v1 [cond-mat.dis-nn]

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Section: Density Fluctuations: Experimental Resultsmentioning

confidence: 99%

Section: Discussion and Perspectivesmentioning

confidence: 99%

Section: Discussion and Perspectivesmentioning

confidence: 99%

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Hyperuniform vortex patterns at the surface of type-II superconductors

Rumi

Sánchez

Elías

et al. 2019

Phys. Rev. Research

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“…Black dots correspond to individual vortices decorated with magnetized Fe nanoparticles attracted to the cores due to their local field gradient. Regular vortex structures with an excess of topological defects induced by confinement [13] are observed for both, N and AN cuboids.…”

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confidence: 92%

“…[5][6][7][8][9] Surface effects in vortex nanocrystals affect its thermodynamic, structural and magnetic properties. [10][11][12][13] For instance, due to surface barriers, the field at which the first vortex penetrates, H P , [14,15] can be larger than the lower critical field H c1 (depending only on the penetration depth λ and the coherence length ξ of the material). This effect becomes more relevant when the surface-to-volume ratio of the number of vortices in nanocrystals enhances.…”

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confidence: 99%

Enhancement of penetration field in vortex matter in mesoscopic superconductors due to Andreev bound states

et al. 2019

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We study the penetration field HP for vortex nanocrystals nucleated in micron-sized samples with edges aligned along the nodal and anti-nodal directions of the d-wave superconducting parameter of Bi2Sr2CaCu2O 8−δ . Here we present evidence that the HP for nanocrystals nucleated in samples with edges parallel to the nodal direction is larger than for the antinodal case, ∼ 72 % at low temperatures. This finding supports the theoretical proposal that surface Andreev bound states appearing in a sample with edges parallel to the nodal direction would produce an anomalous Meissner current that increases the Bean-Livingston barrier for vortex penetration.This has been detected thanks to the nucleation of vortex nanocrystals with a significant surface-to-volume ratio.

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