11B NMR study of pure and lightly carbon-doped MgB2 superconductors

M. Karayanni, G. Papavassiliou, M. Pissas, M. Fardis, K. Papagelis, K. Prassides, T. Takenobu, Y. Iwasa

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We report a 11B NMR line shape and spin-lattice relaxation rate (1/(T1T)) study of pure and lightly carbon-doped MgB 2-xCx for x = 0, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB2 exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase of Hc2 c with carbon doping with respect to pure MgB2. The spin-lattice relaxation rate 1/(T1T) demonstrates clearly the presence of a coherence peak right below Tc in pure MgB2, followed by a typical BCS decrease on cooling. However, at temperatures lower than ≈10 K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon-doped systems both the coherence peak and the BCS temperature dependence of 1/(T1T) weaken, an effect attributed to the gradual shrinking of the σ hole cylinders of the Fermi surface with electron doping.

Original languageEnglish
Pages (from-to)521-528
Number of pages8
JournalJournal of Superconductivity
Volume18
Issue number4
DOIs
Publication statusPublished - 2006
Externally publishedYes

Fingerprint

Superconducting materials
Carbon
Nuclear magnetic resonance
nuclear magnetic resonance
Spin-lattice relaxation
carbon
Magnetic fields
spin-lattice relaxation
Vortex flow
Doping (additives)
magnetic fields
vortices
Boron
Fermi surface
Fermi surfaces
line shape
boron
Cooling
deviation
cooling

Keywords

  • Carbon doping
  • MgB
  • NMR

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)
  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Karayanni, M., Papavassiliou, G., Pissas, M., Fardis, M., Papagelis, K., Prassides, K., ... Iwasa, Y. (2006). 11B NMR study of pure and lightly carbon-doped MgB2 superconductors. Journal of Superconductivity, 18(4), 521-528. https://doi.org/10.1007/s10948-005-0035-9

11B NMR study of pure and lightly carbon-doped MgB2 superconductors. / Karayanni, M.; Papavassiliou, G.; Pissas, M.; Fardis, M.; Papagelis, K.; Prassides, K.; Takenobu, T.; Iwasa, Y.

In: Journal of Superconductivity, Vol. 18, No. 4, 2006, p. 521-528.

Research output: Contribution to journalArticle

Karayanni, M, Papavassiliou, G, Pissas, M, Fardis, M, Papagelis, K, Prassides, K, Takenobu, T & Iwasa, Y 2006, '11B NMR study of pure and lightly carbon-doped MgB2 superconductors', Journal of Superconductivity, vol. 18, no. 4, pp. 521-528. https://doi.org/10.1007/s10948-005-0035-9
Karayanni M, Papavassiliou G, Pissas M, Fardis M, Papagelis K, Prassides K et al. 11B NMR study of pure and lightly carbon-doped MgB2 superconductors. Journal of Superconductivity. 2006;18(4):521-528. https://doi.org/10.1007/s10948-005-0035-9
Karayanni, M. ; Papavassiliou, G. ; Pissas, M. ; Fardis, M. ; Papagelis, K. ; Prassides, K. ; Takenobu, T. ; Iwasa, Y. / 11B NMR study of pure and lightly carbon-doped MgB2 superconductors. In: Journal of Superconductivity. 2006 ; Vol. 18, No. 4. pp. 521-528.
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