Transport in Bulk Superconductors: A Practical Approach?

Rush, J. P.; May-Miller, C. J.; Palmer, Kysen G; Rutter, N A; Dennis, Anthony; Shi, Yunhua; Cardwell, D. A.; Durrell, John

doi:10.1109/tasc.2016.2537647

Cited by 10 publications

(7 citation statements)

References 28 publications

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“…Distinct I-V characteristics were observed above and below the transition temperature. The measurements suggest that well into the superconducting phase, LaH 10AEx could exhibit very large critical current densities [15,39]. In this experiment, part of the sample had spread outside the central culet, giving rise to the formation of lower pressure phases with their own transition temperatures.…”

mentioning

confidence: 75%

Pushing Towards Room-Temperature Superconductivity

Zurek

2019

Physics

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Recent predictions and experimental observations of high T c superconductivity in hydrogen-rich materials at very high pressures are driving the search for superconductivity in the vicinity of room temperature. We have developed a novel preparation technique that is optimally suited for megabar pressure syntheses of superhydrides using modulated laser heating while maintaining the integrity of sample-probe contacts for electrical transport measurements to 200 GPa. We detail the synthesis and characterization of lanthanum superhydride samples, including four-probe electrical transport measurements that display significant drops in resistivity on cooling up to 260 K and 180-200 GPa, and resistivity transitions at both lower and higher temperatures in other experiments. Additional current-voltage measurements, critical current estimates, and low-temperature x-ray diffraction are also obtained. We suggest that the transitions represent signatures of superconductivity to near room temperature in phases of lanthanum superhydride, in good agreement with density functional structure search and BCS theory calculations.

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mentioning

confidence: 75%

Pushing Towards Room-Temperature Superconductivity

Zurek

2019

Physics

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“…The assumed relationship for the n-value (see table 1) ensures the modified resistivity equation converges towards the normal-state resistivity ρ nm = 3.5×10 −6 Ω.m at the critical temperature, T c . While the 2D axisymmetric model and the assumption for J c (B, T ) neglect any angular dependence of J c (which is common for bulk superconductor magnetisation problems [32] due to difficulties in measuring the angular dependence in bulks [33]) and any spatial variation of J c within the bulk volume [34,35], it is nevertheless shown in section 3 that the modelling framework and simplified assumptions accurately replicate the experimental data reported in [26].…”

Section: Electromagnetic Considerationsmentioning

confidence: 95%

Modelling and mitigating flux jumps in bulk high-temperature superconductors during quasi-static, high-field magnetisation

Cientanni

Ainslie

2023

Supercond. Sci. Technol.

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(RE)-Ba2Cu3O7−δ bulk superconductors acting as permanent trapped field magnet analogues have been shown to trap fields in excess of 17 T. However, the occurrence of thermomagnetic instabilities during their magnetisation process can limit their performance. In 2019, Naito et al. trapped 15.1 T in a (Y)-BaCuO bulk-pair under applied fields of up to 22 T (Journal of Applied Physics 126, 243901 (2019)), whilst also documenting the mechanical failure of the bulks due to a flux jump. Here, we accurately numerically model this experiment and the observed flux jump, providing insight to the experimental results; such as the role of heating, the presence of thermal gradients, and a possible reason for the location of the bulk-pair fracturing. Extending the study with an investigation into the role of enhanced cooling of the bulk-pair, the influence of cooling power on the calculated trapped field and flux jump is explored. We finally propose and numerically investigate a new composite bulk configuration, consisting of stacks of (Y)-BaCuO bulk and interspaced metallic discs, to enhance the thermal stability of the bulk-pair, to ultimately improve the trapped field performance.

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“…In addition, these bulks usually contain numerous cracks, secondary phases and inclusions that can be of this characteristic dimension and therefore potentially block any transport current completely. Despite these challenges, transport measurements have indeed been reported on (RE)BCO bulk materials by Rush et al on a GdBCO single-grain bulk [7] and by Kikegawa et al on a mixed rare earth (Nd-Eu-Gd) BCO sample [9]. Both of these samples were produced via the top-seeded melt growth (TSMG) technique, which typically and unavoidably produces a sample microstructure that contains many pores and cracks due to limitations of the processing technique.…”

Section: J Cmentioning

confidence: 99%

“…These samples (typically ~ 25 mm in diameter) can trap magnetic fields of ~ 0.8-1 T at 77 K and ~ 6-8 T at 30 K at the sample surface [2,3,5] when fully magnetised. Information on J c in bulk, single grain (RE)BCO superconductors is often obtained via magnetometry, which relies fundamentally on several computational assumptions [6,7]. This usually involves a combination of a SQUID magnetometer within a cryomagnet, such as a Physical Property Measurement System (PPMS), to determine the magnetic hysteresis (M-H) loops from which the (magnetic) critical current densities (J c mag ) are determined using the extended Bean critical-state model [6].…”

Section: Introductionmentioning

confidence: 99%

Transport measurements in single-grain GdBCO+Ag bulk superconductors processed by infiltration growth

et al. 2023

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Transport measurements performed on a cross-sectional slice prepared from a bulk GdBa2Cu3O7-x-Ag single-grain superconductor of 25 mm in diameter are described and the results presented. The sample, which was fabricated via the buffer-assisted top-seeded infiltration growth process, was capable of trapping a maximum magnetic field of ~ 1 T at 77 K. Transport measurements on superconducting, bulk single-grain RE-Ba-Cu-O [(RE)BCO] samples are generally very challenging due to their large critical current densities and poor mechanical properties. We present a straightforward and reliable approach to prepare reproducibly specimens from the parent single grain and results of transport property measurements on these samples in a commercial Physical Property Measurement System (PPMS). Critical current densities determined via magnetic and transport measurements are compared and discussed.

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Transport in Bulk Superconductors: A Practical Approach?

Cited by 10 publications

References 28 publications

Pushing Towards Room-Temperature Superconductivity

Pushing Towards Room-Temperature Superconductivity

Modelling and mitigating flux jumps in bulk high-temperature superconductors during quasi-static, high-field magnetisation

Transport measurements in single-grain GdBCO+Ag bulk superconductors processed by infiltration growth

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