Critical Current Density and Flux Pinning Properties in Superconducting MgB₂ with and without SiC Doping

Abstract:

It is well known that SiC doping in superconducting MgB₂ improves the upper critical magnetic field (B_c2) and the critical current density (J_c) under high magnetic field. However, the relationship between SiC doping and the flux pinning mechanism has not been clarified. In this study, several MgB₂ samples with and without SiC doping were prepared by the conventional in situ powder-in-tube method. The critical current densities and the force-displacement characteristics of fluxoids in samples were investigated by an ac inductive measurement (Campbell’s method). The Labusch parameter (α_L) and the interaction distance (d_i) were estimated from the obtained force-displacement profile. It was found that SiC doping enhances the values of α_L, but does not change the characteristics of the magnetic field dependence of α_L apparently. Namely, α_L vs. B^3/2 characteristics in the pure samples and SiC doped samples are almost the same. Such a result of α_L properties implies that the pinning mechanism in the SiC doped samples could be consistent with the conventional pinning theory. On the other hand, d_i, which is considered to be proportional to the size of pinning potential, decreases rapidly with increasing magnetic field, especially in the pure samples. For high magnetic field region, the variations of d_i were deduced to be caused by flux creep. The depth of pinning potential, U₀, was estimated by using the values of α_L and d_i. The values of U₀ give evidence of that SiC doping can prevent the flux bundles moving to another pinning center under high magnetic field.

• Periodical: Materials Science Forum (Volume 750)
• Pages: 293-297
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.750.293
• Online since: March 2013
• Authors: Wen Xu Sun, Bao Rong Ni, Akiyoshi Matsumoto, Hiroaki Kumakura
• Keywords: Critical Current Density, Flux Pinning, Interaction Distance, Labusch Parameter, MgB₂, Pinning Potential

References

[1] A. Serquis, G. Serrano, S. M. Moreno, L. Civale, B. Maiorov, F. Balakirev and M. Jaime. Supercond. Sci. Technol. 20 (2007) L12.

DOI: 10.1088/0953-2048/20/4/l02

[2] T. Matsushita. Flux pinning in superconductors, Spring-Verlag, Berlin Heidelberg (2007), p.416.

[3] H. Yamada, M. Igarashi, H, Kitaguchi, A. Matsumoto, and H. Kumakura. Supercond. Sci. Technol. 22 (2009) 075005.

[4] A. Matsumoto, H. Kumakura, and H. Kitaguchi. Appl. Phys. Letter 89(2006), 132508.

[5] A. Matsumoto, H. Kumakura, H. Kitaguchi and H. Hatakeyama. Supercond. Sci. Technol 16(2003), p.926–930.

[6] M. D. Sumptiona, M. Bhatia, M. Rindfleisch, M. Tomsic, S. Soltanian, S. X. Dou and E. W. Collings. Appl. Phys. Letter 86 (2005) 092507.

DOI: 10.1063/1.1872210

[7] G. Serrano, A. Serquis, S. X. Dou, S. Soltanian, L. Civale and B. Maiorov. J. Appl. Phys. 103 (2008), 023907.