| Autor: |
Serrano, G., Serquis, A., Dou, S. X., Soltanian, S., Civale, L., Maiorov, B., Holesinger, T. G., Balakirev, F., Jaime, M. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; Jan2008, Vol. 103 Issue 2, p023907, 5p, 1 Diagram, 2 Charts, 3 Graphs |
| Abstrakt: |
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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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