Properties of superconducting NbTi superfine filament composites with diameters ≲0.1 μm

Hlasnik, I.; Takács, S.; Burjak, V.P.; Majoroš, M.; Krajčik, J.; Krempaský, Ľ.; Polák, M.; Jergel, M.; Korneeva, T.A.; Mironova, O. N.; Ivan, I.

doi:10.1016/0011-2275(85)90176-6

Cited by 79 publications

(8 citation statements)

References 13 publications

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“…Then, pinning effects are dramatically reduced 7 . Yet there have been alluring communications of an enhancement of superconducting parameters by magnetic field and a negative magnetoresistance in thin superconducting wires [8][9][10][11] . These observations however promising challenged our understanding, as they often referred to the field and temperature range where strong vortex pining were not expected.…”

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confidence: 99%

Magnetic field-induced dissipation-free state in superconducting nanostructures

et al. 2013

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A superconductor in a magnetic field acquires a finite electrical resistance caused by vortex motion. A quest to immobilize vortices and recover zero resistance at high fields made intense studies of vortex pinning one of the mainstreams of superconducting research. Yet, the decades of efforts resulted in a realization that even promising nanostructures, utilizing vortex matching, cannot withstand high vortex density at large magnetic fields. Here, we report a giant reentrance of vortex pinning induced by increasing magnetic field in a W-based nanowire and a TiN-perforated film densely populated with vortices. We find an extended range of zero resistance with vortex motion arrested by self-induced collective traps. The latter emerge due to order parameter suppression by vortices confined in narrow constrictions by surface superconductivity. Our findings show that geometric restrictions can radically change magnetic properties of superconductors and reverse detrimental effects of magnetic field.

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confidence: 99%

Magnetic field-induced dissipation-free state in superconducting nanostructures

et al. 2013

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“…Later analysis of the composite in [29] showed that the isolated superconducting rods became connected, due to strong proximity coupling and gross deformation of the microstructure, so that the nanostructure was not much different from a conventional composite when 50% Nb was used [31]. The barrier concept is also similar to multifilamentary Nb-Ti composites with filament diameters less than 200 nm [52,53], which have copper as the continuous barrier phase. Good filament uniformity was maintained to 48 nm filament diameter in one of these [54], and strong flux pinning was observed at low field due to the surface barrier [35,53].…”

Section: Rod and Tube/foil Designsmentioning

confidence: 99%

Advances in high-field superconducting composites by addition of artificial pinning centres to niobium-titanium

Cooley

Motowidlo

1999

Supercond. Sci. Technol.

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Artificial pinning-centre (APC) niobium-titanium composites attain critical current density J c values higher than 4000 A mm −2 at 5 T, 4.2 K, surpassing the barrier reached by the conventional Nb-Ti composite process. At 2 T APC composites achieve more than double the J c of conventional composites, making them particularly well suited for low-field applications. On the other hand, APC composites are inferior to conventional composites at 8 T, due to weak high-field pinning and reduced upper critical field. This review discusses fabrication techniques, microstructural development and superconducting and flux-pinning properties of APC composites. Key elements and underlying issues for achieving higher J c are identified and discussed in terms of the current state of the art.

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“…A reduction in T c was observed for specimens having a filament diameter of 0.7 µm. The dependence of T c on the filament diameter due to the proximity effect is expressed by the following formula [10]:…”

Section: Critical Temperaturementioning

confidence: 99%

Characteristics of multifilamentary wires for a.c. use developed by the bronze process using diffusion barrier techniques

Miura

Matsumoto

Tanaka

et al. 1996

Supercond. Sci. Technol.

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Nb 3 Sn multifilamentary superconducting wires for a.c. use were developed by the bronze method using Cu diffusion barrier techniques. To reduce a.c. losses, the filament diameter was designed to be less than 0.5 µm and the final resistivity of the bronze matrix was increased using a Cu alloy diffusion barrier with the addition of Si and Mn elements around the filaments. As a result, interfilamentary proximity coupling could be prevented until a filament spacing of 0.3 µm and hysteresis losses for the wires reached lower values, from 1.75 kJ m −3 to 12.18 kJ m −3 at a magnetic field amplitude of 0.5 T under controlled reaction heat treatment. The perpendicular resistivity of the matrix between the filaments estimated from the coupling loss was about 2.5 × 10 −8 m, which was considerably less than the resistivity value of the matrix estimated after the reaction. This was thought to be due to an extreme reduction in Sn concentration between the filaments. Furthermore, a small a.c. coil was fabricated by winding a stranded cable fabricated in this way. The a.c. loss of the coil at 50 Hz in a central magnetic field of 0.5 T was 178 kW m −3 and the a.c. quench current at 50 Hz was 195 A, which is about 10% lower than the critical current on the load line. This degradation was due to the temperature rise in the cable caused by a.c. loss.

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Properties of superconducting NbTi superfine filament composites with diameters ≲0.1 μm

Cited by 79 publications

References 13 publications

Magnetic field-induced dissipation-free state in superconducting nanostructures

Magnetic field-induced dissipation-free state in superconducting nanostructures

Advances in high-field superconducting composites by addition of artificial pinning centres to niobium-titanium

Characteristics of multifilamentary wires for a.c. use developed by the bronze process using diffusion barrier techniques

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