The onset of dissipation in high-temperature superconductors: magnetic hysteresis and field dependence

Talantsev, E. F.; Strickland, N. M.; Wimbush, Stuart C.; Brooks, J.; Pantoja, A. E.; Badcock, Rodney A.; Storey, J. G.; Tallon, J. L.

doi:10.1038/s41598-018-32811-6

Cited by 9 publications

(3 citation statements)

References 30 publications

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“…The differences between the resistive T c and magnetic estimations of T c probably reflect small inhomogeneities in the film since the resistive measurement detects the strongest percolation path through the entire sample, while the magnetisation data are only collected from the "local" area near the Hall sensor. The estimated critical current density at 77 K is within the range of previously estimated values obtained from transport measurements at the same temperature, with any difference likely to be due to the different in-field and self-field measurement conditions used [18,19,28]. Estimated J c values for the smaller field range near T c are systematically smaller than those for the larger sweep range, reflecting the much lower sweep rates (approximately 30x lower) for these loops, allowing much more time for the critical state to relax due, for example, to flux creep processes.…”

Section: Characterisation Of the Hts Tapessupporting

confidence: 77%

Imaging of Strong Nanoscale Vortex Pinning in GdBaCuO High-Temperature Superconducting Tapes

et al. 2021

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The high critical current density of second-generation high-temperature superconducting (2G-HTS) tapes is the result of the systematic optimisation of the pinning landscape for superconducting vortices through careful engineering of the size and density of defects and non-superconducting second phases. Here, we use scanning Hall probe microscopy to conduct a vortex-resolved study of commercial GdBaCuO tapes in low fields for the first time and complement this work with “local” magnetisation and transport measurements. Magnetic imaging reveals highly disordered vortex patterns reflecting the presence of strong pinning from a dense distribution of nanoscale Gd2O3 second-phase inclusions in the superconducting film. However, we find that the measured vortex profiles are unexpectedly broad, with full-width-half-maxima typically of 6 μm, and exhibit almost no temperature dependence in the range 10–85 K. Since the lateral displacements of pinned vortex cores are not expected to exceed the superconducting layer thickness, this suggests that the observed broadening is caused by the disruption of the circulating supercurrents due to the high density of nanoscale pinning sites. Deviations of our local magnetisation data from an accepted 2D Bean critical state model also indicate that critical state profiles relax quite rapidly by flux creep. Our measurements provide important information about the role second-phase defects play in enhancing the critical current in these tapes and demonstrate the power of magnetic imaging as a complementary tool in the optimisation of vortex pinning phenomena in 2G-HTS tapes.

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Section: Characterisation Of the Hts Tapessupporting

confidence: 77%

Imaging of Strong Nanoscale Vortex Pinning in GdBaCuO High-Temperature Superconducting Tapes

et al. 2021

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“…In this regard, recently registered effect [81] of the linearization of surface magnetic field, Bsurf(I), vs transport current rise at the onset of power dissipation can be considered as a new option. We showed recently, that this effect [81,82] works when external magnetic field, Bappl, is applied to the sample [83,84].…”

Section: Self-field Critical Currents In Compressed Lah10mentioning

confidence: 99%

Classifying hydrogen-rich superconductors

Talantsev

2019

Mater. Res. Express

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The era of near-room-temperature superconductivity started after experimental discovery by Drozdov et al (2015 Nature 525 73) who found that compressed H3S exhibits superconducting transition at Tc = 203 K. To date, the record near-room-temperature superconductivity stands with another hydrogen-rich highly compressed compound, LaH10 (Somayazulu et al 2019 Phys. Rev. Lett. 122 027001), which has critical temperature of > 240 . In this paper, we analyse available upper critical field, Bc2(T), data for LaH10 (Drozdov et al 2019 Nature 569 528) and report that this compound in all consideredscenarios has the ratio of Tc to the Fermi temperature, TF, 0.009 < Tc/TF < 0.038, which is typical range for unconventional superconductors. In attempt to extend our finding, we examined experimental Bc2(T) data for superconductors in the palladium-hydrogen (PdHx) and thorium-hydrogen-deiterium (ThH-ThD) systems and surprisingly find that superconductors in both these systems also fall into unconventional superconductors band.Taking in account that H3S has the ratio of 0.012 < Tc/TF < 0.039 (Talantsev 2019 Mod. Phys. Lett. B 33 1950195) we come to conclusion that in the Uemura plot all discovered to date hydrogen-rich superconductors, i.e. Th4H15-Th4D15, PdHx, H3S and LaH10 (in this list we do not include NbTiHx, PtHx, SiH4, and PH3 for which experimental data beyond Tc are unknown), lie in same band as all unconventional superconductors, particularly heavy

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“…According to Brandt et al 39 , this relaxation is due to the "walking-motion" of vortices in the thin tape. However, the dynamic magneto-resistance can also be explained by the Critical State Model 41 , and hence the presence of vortices is not strictly required 42 . Below threshold field, , a shielded region of "frozen-flux" exists within the center, such that no change in field is experienced by the DC current flowing in this shielded region, and hence the dynamic magneto-resistance is zero because there is no flux crossing the superconductor 41 .…”

Section: Introductionmentioning

confidence: 99%

Modeling cross-field demagnetization of superconducting stacks and bulks for up to 100 tapes and 2 million cycles

Dadhich

Pardo

2020

Sci Rep

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Superconducting stacks and bulks can act as very strong magnets (more than 17 T), but they lose their magnetization in the presence of alternating (or ripple) transverse magnetic fields, due to the dynamic magneto-resistance. This demagnetization is a major concern for applications requiring high run times, such as motors and generators, where ripple fields are of high amplitude and frequency. We have developed a numerical model based on dynamic magneto-resistance that is much faster than the conventional Power-Law-resistivity model, enabling us to simulate high number of cycles with the same accuracy. We simulate demagnetization behavior of superconducting stacks made of 10–100 tapes for up to 2 million cycles of applied ripple field. We found that for high number of cycles, the trapped field reaches non-zero stationary values for both superconducting bulks and stacks; as long as the ripple field amplitudes are below the parallel penetration field, being determined by the penetration field for a single tape in stacks. Bulks keep substantial stationary values for much higher ripple field amplitudes than the stacks, being relevant for high number of cycles. However, for low number of cycles, stacks lose much less magnetization as compared to bulks.

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The onset of dissipation in high-temperature superconductors: magnetic hysteresis and field dependence

Cited by 9 publications

References 30 publications

Imaging of Strong Nanoscale Vortex Pinning in GdBaCuO High-Temperature Superconducting Tapes

Imaging of Strong Nanoscale Vortex Pinning in GdBaCuO High-Temperature Superconducting Tapes

Classifying hydrogen-rich superconductors

Modeling cross-field demagnetization of superconducting stacks and bulks for up to 100 tapes and 2 million cycles

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