Meissner holes in superconductors

Vlasko-Vlasov, Vitalii; Welp, U.; Crabtree, G. W.; Gunter, D.; Kabanov, V. V.; Никитенко, В. И.

doi:10.1103/physrevb.56.5622

Cited by 53 publications

(43 citation statements)

References 20 publications

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“…The Meissner holes are formed by closed vortex loops, which collapse below some minimum diameter dictated by pinning and leave a flux-free cylinder. They carry enhanced currents and similar to plasma current filaments in magnetic fields, are unstable to bending as discussed in detail in ref [25]. This results in the local enhancement of B ⊥ inside the flux front meanders as illustrated in Fig.1f.…”

Section: Magnetization In Perpendicular Field After Zero-field Coolingmentioning

confidence: 84%

“…When the field is decreased to zero, the symmetry of the envelope-shaped pattern remains the same, although the current direction and flux gradients are inverted (Fig.1e). Subsequent application of a negative field induces the appearance of so-called Meissner holes [25,21] at the flux front between "positive" and "negative" vortices that propagate inside and remagnetize the sample. (see Fig.1f).…”

Section: Magnetization In Perpendicular Field After Zero-field Coolingmentioning

confidence: 99%

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Flux cutting in high-Tcsuperconductors

et al. 2015

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We performed magneto-optical study of flux distributions in a YBCO crystal under various applied crossed-field orientations to elucidate the complex nature of magnetic flux cutting in superconductors. Our study reveals unusual vortex patterns induced by the interplay between flux-cutting and vortex pinning. We observe strong flux penetration anisotropy of the normal flux B ⊥ in the presence of an in-plane field H || and associate the modified flux dynamics with staircase structure of tilted vortices in YBCO and the flux-cutting process.We demonstrate that flux-cutting can effectively delay vortex entry in the direction transverse to H || . Finally, we elucidate details of the vortex-cutting and reconnection process using time-dependent Ginzburg-Landau simulations.

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Section: Magnetization In Perpendicular Field After Zero-field Coolingmentioning

confidence: 84%

Section: Magnetization In Perpendicular Field After Zero-field Coolingmentioning

confidence: 99%

Flux cutting in high-Tcsuperconductors

et al. 2015

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“…The heat release in the annihilation zone is suggested as a probable explanation of this phenomenon. Another explanation is based upon the concept of magnetic field concentration inside the bend of a current line 38 . Furthermore, as discussed in Ref.…”

Section: B Resultsmentioning

confidence: 99%

Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

et al. 1999

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Magnetic flux distribution across a high-temperature superconductor strip is measured using magneto-optical imaging at 15 K. Both the current-carrying state and the remanent state after transport current are studied up to the currents 0.97Ic where Ic is the critical current. To avoid overheating of the sample current pulses with duration 50 ms were employed. The results are compared with predictions of the Bean model for the thin strip geometry. In the current-carrying state, reasonable agreement is found. However, there is a systematic deviation -the flux penetration is deeper than theoretically predicted. A much better agreement is achieved by accounting for flux creep as shown by our computer simulations. In the remanent state, the Bean model fails to explain the experimental results. The results for the currents I ≤ 0.7Ic can be understood within the framework of our flux creep simulations. However, after the currents I > 0.7Ic the total flux trapped in a strip is substantially less than predicted by the simulations. Furthermore, it decreases with increasing current. Excessive dissipation of power in the annihilation zone formed in the remanent state is believed to be the source of this unexpected behavior.

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“…The phase image (k) shows a small part of the whole current loop in a region of the sample surface where the current path is measured (the dark edge between the regions of different phase colors). The meandering structure of the current path shown by the MFM phase line looks similar to the one observed in high-temperature superconducting oxides in remanence [48,49]. The line scans of the phase (a-e) were taken normal to the current line.…”

Section: Discussionmentioning

confidence: 99%

Evidence for room temperature superconductivity at graphite interfaces

Esquinazi

Precker

Stiller

et al. 2017

Quantum Stud.: Math. Found.

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In the last 43 years several hints were reported suggesting the existence of granular superconductivity above room temperature in different graphite-based systems. In this paper some of the results are reviewed, giving special attention to those obtained in water and n-heptane treated graphite powders, commercial and natural bulk graphite samples with different characteristics as well as transmission electron microscope (TEM) lamellae. The overall results indicate that superconducting regions exist and are localized at certain internal interfaces of the graphite structure. The existence of the rhombohedral graphite phase in all samples with superconducting-like properties suggests its interfaces with the Bernal phase as a possible origin for the high-temperature superconductivity, as theoretical calculations predict. High precision electrical resistance and magnetization measurements were used to identify a transition at Tc > ∼ 350 K. To check for the existence of true zero resistance paths in the samples we used local magnetic measurements, which results support the existence of superconducting regions at such high temperatures.

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Meissner holes in superconductors

Cited by 53 publications

References 20 publications

Flux cutting in high-Tcsuperconductors

Flux cutting in high-Tcsuperconductors

Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

Evidence for room temperature superconductivity at graphite interfaces

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