Critical data of some A15 type superconductors in transverse fields up to 230 kOe

Otto, G.; Saur, E.; Wizgall, H.

doi:10.1007/bf00628331

Cited by 38 publications

(3 citation statements)

References 15 publications

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“…41 The intersection of the ␥ m ͑H͒ line with the ␥ limit defines H c2 ͑0͒ = 25 T, in agreement with the previous method, without having to assume any functional shape for H c2 ͑T͒. Resistively determined transitions for Nb 3 Sn wires in static fields up to 23 T have yielded H c2 ͑0͒ = 24.5 T. 42 We now concentrate on the anomaly in the specific heat at T → 0 which is visible at the origin of Fig. 4.…”

Section: Electronic Specific Heat In a Magnetic Fieldsupporting

confidence: 84%

Specific heat ofNb3Sn: The case for a second energy gap

Guritanu

Goldacker²,

Bouquet

et al. 2004

Phys. Rev. B

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We present specific-heat data for Nb 3 Sn, a well-known technically applied superconductor with a critical temperature T c Х 18 K, in the temperature range from 1.2 to 200 K in zero magnetic field, and from 1.5 to 22 K in fields H ഛ 16 T. The particularly dense and homogeneous polycrystalline sample used for this study is characterized in detail. We determine the bulk upper critical field H c2 ͑T͒ from specific-heat data, and the Sommerfeld constant ␥ from the entropy S͑T͒. We investigate in detail a low-temperature anomaly already noticed in previous investigations in zero field, and find that this feature can be quantitatively ascribed to the presence of a second superconducting gap 2⌬ S ͑0͒Х0.8k B T c , in addition to the main one 2⌬ L ͑0͒Х4.9k B T c . The signature of this minor gap, which affects 7.5% of the electronic density-of-states, vanishes in high fields.

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Section: Electronic Specific Heat In a Magnetic Fieldsupporting

confidence: 84%

Specific heat ofNb3Sn: The case for a second energy gap

Guritanu

Goldacker²,

Bouquet

et al. 2004

Phys. Rev. B

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“…5 ). From this analysis, we obtain μ 0 H c 2 (0) = 20 T, which is consistent with the previously-reported bulk value of H c2 = 23.5 T for V 3 Si 27 . Knowing , we can also calculate the superconducting coherence length in our V 3 Si to be 4 nm, using the relation 28 , where is the magnetic flux quantum, also consistent with previous reports 29 .…”

Section: Resultssupporting

confidence: 91%

Thin-film synthesis of superconductor-on-insulator A15 vanadium silicide

Zhang

Bollinger

et al. 2021

Sci Rep

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We present a new method for thin-film synthesis of the superconducting A15 phase of vanadium silicide with critical temperature higher than 13 K. Interdiffusion between a metallic vanadium film and the underlying silicon device layer in a silicon-on-insulator substrate, at temperatures between 650 and 750 °C, favors formation of the vanadium-rich A15 phase by limiting the supply of available silicon for the reaction. Energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction verify the stoichiometry and structure of the synthesized thin films. We measure superconducting critical currents of more than 106 amperes per square centimeter at low temperature in micron-scale bars fabricated from the material, and an upper critical magnetic field of 20 T, from which we deduce a superconducting coherence length of 4 nm, consistent with previously reported bulk values. The relatively high critical temperature of A15 vanadium silicide is an appealing property for use in silicon-compatible quantum devices and circuits.

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“…Spin paramagnetic effect is found to be important for superconductors with high critical fields. For instance, in A15 compounds [31] and in 11 Fe based systems [32], critical fields were found to be suppressed significantly due to spin paramagnetic effects and could be explained only when WHH models with a ¹ 0 is invoked. However, in the case of BDD, given the relatively low H c2 WHH (0) values, paramagnetic effects may not be important.…”

Section: Upper Critical Fieldmentioning

confidence: 99%

Flux pinning and improved critical current density in superconducting boron doped diamond films

2018

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The ability to carry transport current in a magnetic field is the most important aspect of a superconductor. We present a detailed analysis of the upper critical field (H c2 (0)) and vortex dynamics in superconducting boron doped diamond (BDD) films. H c2 (0) measured on the samples of different doping levels revealed a high critical field of up to 7.3 T. Pinning potential U 0 , estimated using thermally activated flux-flow (TAFF) model shows that U 0 is of the order of 10 2 K. Self-field critical current density (J c ) estimated for the superconducting BDD films showed large J c ∼10 7 A/cm 2 due to enhanced flux trapping.

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Critical data of some A15 type superconductors in transverse fields up to 230 kOe

Cited by 38 publications

References 15 publications

Specific heat ofNb3Sn: The case for a second energy gap

Specific heat ofNb3Sn: The case for a second energy gap

Thin-film synthesis of superconductor-on-insulator A15 vanadium silicide

Flux pinning and improved critical current density in superconducting boron doped diamond films

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