A Serquis et al 2007 Supercond. Sci. Technol. 20 L12 doi:10.1088/0953-2048/20/4/L02
A Serquis1, G Serrano1, S M Moreno1, L Civale2, B Maiorov2, F Balakirev3 and M Jaime3
Show affiliationsThe use of MgB2 in superconducting applications still awaits the development of a MgB2-based material where current-carrying performance and critical magnetic field are optimized simultaneously. We achieved this by doping MgB2 with double-wall carbon nanotubes (DWCNT) as a source of carbon in polycrystalline samples. The optimum nominal DWCNT content for increasing the critical current density, Jc, is in the range 2.5–10 at.% depending on field and temperature. Record values of the upper critical field, Hc2(4 K) = 41.9 T (with extrapolated Hc2(0)≈44.4 T), are reached in a bulk sample with 10 at.% DWCNT content. The measured Hc2 versus T dependences for all samples are successfully described using a theoretical model for a two-gap superconductor in the dirty limit first proposed by Gurevich and co-workers.
74.62.Dh Effects of crystal defects, doping and substitution
74.25.Op Mixed states, critical fields, and surface sheaths
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
Issue 4 (April 2007)
Received 22 December 2006, in final form 30 January 2007
Published 26 February 2007
A Serquis et al 2007 Supercond. Sci. Technol. 20 L12
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