Publication Details

This article was originally published as Serrano, G, Serquis, A, Dou, SX, Soltanian, S, Civale, L, Maiorov, B, Holesinger, TG, Balakirev, F and Jaime, M, SiC and carbon nanotube distinctive effects on the superconducting properties of bulk MgB2, Journal of Applied Physics, 103(2), 2008, 023907-1-023907-5. Copyright American Institute of Physics 2008. Original journal article available here


This work describes in detail the simultaneous enhancement of the upper critical field (Hc2) and the critical current density (Jc) of MgB2 bulk samples doped with nano-SiC particles, as well as single-walled and double-walled (dw) carbon nanotubes (CNTs). The magnetization properties were examined in a superconducting quantum interference device magnetometer, and four-probe transport measurements were performed using a 50 T pulsed magnet to determine Hc2(T).We found that the Jc enhancement is similar in all doped samples at 5 K but nano-SiC addition is more effective to improve the flux pinning in the high temperature range (T≥20 K); this improvement cannot solely be attributed to the C incorporation to the lattice but also to the presence of other types of defects (i.e., several kinds of nanoinclusions). CNTs produce a better C incorporation that is more effective to enhance Hc2 [i.e., dwCNT-doped samples reached a record Hc2(0)~44 T value for bulk MgB2]. All the Hc2(T) curves obtained for different types of doping can be successfully described using a model for a two-gap superconductor in the dirty limit.

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