Ferromagnetic Artificial Pinning Centers in Multifilamentary Superconducting Wires
We fabricated lnultifilamentary NbTi wires with ferromagnetic (FM) artificial pinning centers (APCs) to enhance the critical current density (Jc) in magnetic fields. We used a bundle and draw technique to process the APC wires with either Ni or Fe as the pinning centers. Both wires produced higher Jc in the high field range (5–9 T) than previous non-magnetic APC wires similarly processed, even though we have not yet optimized pin percentage. Using a magnetometer we found that the pins remained ferromagnetic for the wires with maximum Jc. However, we did observe a substantial loss of FM material for the wires where the pin diameter approached 3 nm. Thus, we expect further enhancement of Jc with better pin quality.
KeywordsCoherence Length Final Size Large Filament Pinning Center Wire Size
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- 1.B. A. Zeitlin, M. S. Walker, and L. R. Motowidlo, United States Patent No. 4803310 Feb. 7, 1989. (IGC Disclosure 1.983).Google Scholar
- 3.L. D. Cooley, P. J. Lee, and D. C. Larbalestier, “Is Magnetic Pinning A dominant Mechanism in Nb-Ti”, JEEE Trans. MAC, 27: 1096 (1991).Google Scholar
- 4.H. C. Kanithi, P. Valaris, L. R. Motowidlo, B. A. Zeitlin and R. Scanlon, “Further Developments in NbTi Superconductors with Artificial Pinning Centers”, Adv. Cryog. Eng. 38B: 675(1992).Google Scholar
- 6.D. R. Dietderich, S. Eylon and R. Scanlon, Adv. Cryog. Eng. 38B: 685 (1992).Google Scholar
- 8.L. R. Motowidlo, B. A. Zeitlin, M. S. Walker, P. Haldar, J. D. McCambridge, N. D. Rizzo, X. S. Ling, and D. E. Prober, “Multifilamentary NbTi with Artificial Pinning Centers: The Effect of Alloy, Pin Material and Ceometry on the Superconducting Properties”, IEEE Trans. Appl. Supercond. 3: 1366 (1993).CrossRefGoogle Scholar
- 13.L. R. Motowidlo, B. A. Zeitlin, X. S. Ling, N. D. Rizzo, J. D. McCambridge, and I. E. Prober, “Flux Pinning in NbTi Superconductors with Engineered Pinning Centers”, in “Processing Long Length Supercond.”, TMS, Warrendale (1994).Google Scholar
- 14.C. Kittel, “Introduction to Solid State Physics, 6th Edition”, John Wiley&Son, New York, p.429 (1986).Google Scholar
- 17.L. D. Cooley and D. C. Larbalestier, “Quantification of Flux Pinning by the Surface Barrier in Submicron-Filament Nb-Ti Composite Wires”, Proc. 8th US-Japan Workshop, Univ. of Wisconsin, Madison (1993).Google Scholar