Strong coupling s-wave superconductivity in MgB2: 11111111B-NMR Study of MgB2 and Al-dopedMgB2

Hisashi Kotegawa, Kenji Ishida, Yoshio Kitaoka, Takahiro Muranaka, Norimasa Nakagawa, Hiroyuki Takagiwa, Jun Akimitsu

Research output: Contribution to journalArticle

Abstract

We have measured nuclear spin-lattice relaxation time, T1 of 11B in MgB2 and Al-doped MgB 2-T1T = const, behavior is observed in the normal state, indicating the absence of strong magnetic correlation. In the superconducting (SC) state of MgBg, 1/T1 shows a tiny coherence peak just below Tg and decreases exponentially with a large SC gap of 2A/kBTc ∼ 5. These results suggest that M gB2 is a strong coupling s-wave superconductor. As Al 3+ is doped into Mg2+ site, 1/T1T which is proportional to the square of the density of states (DOS) decreases. The variation of Tc against the DOS deduced from 1/T1T is fitted by McMillan equation, and the Debye frequency ω and the electron-phonon coupling constant A were estimated as ∼ 700 K and ∼ 0.87, respectively. Both are in good agreement with the values from theoretical works. The high-Tc superconductivity in MgB2 is considered to occur through strong coupling between electrons and high frequency-phonon.

Original languageEnglish
Pages (from-to)332-334
Number of pages3
JournalJournal of the Physical Society of Japan
Volume71
Issue numberSUPPL.
Publication statusPublished - 2002
Externally publishedYes

Fingerprint

superconductivity
nuclear magnetic resonance
spin-lattice relaxation
nuclear spin
electrons
relaxation time

Keywords

  • Al-doped MB
  • MB
  • McMillan equation
  • NMR
  • S-wave superconductivity

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Kotegawa, H., Ishida, K., Kitaoka, Y., Muranaka, T., Nakagawa, N., Takagiwa, H., & Akimitsu, J. (2002). Strong coupling s-wave superconductivity in MgB2: 11111111B-NMR Study of MgB2 and Al-dopedMgB2. Journal of the Physical Society of Japan, 71(SUPPL.), 332-334.

Strong coupling s-wave superconductivity in MgB2 : 11111111B-NMR Study of MgB2 and Al-dopedMgB2. / Kotegawa, Hisashi; Ishida, Kenji; Kitaoka, Yoshio; Muranaka, Takahiro; Nakagawa, Norimasa; Takagiwa, Hiroyuki; Akimitsu, Jun.

In: Journal of the Physical Society of Japan, Vol. 71, No. SUPPL., 2002, p. 332-334.

Research output: Contribution to journalArticle

Kotegawa, H, Ishida, K, Kitaoka, Y, Muranaka, T, Nakagawa, N, Takagiwa, H & Akimitsu, J 2002, 'Strong coupling s-wave superconductivity in MgB2: 11111111B-NMR Study of MgB2 and Al-dopedMgB2', Journal of the Physical Society of Japan, vol. 71, no. SUPPL., pp. 332-334.
Kotegawa H, Ishida K, Kitaoka Y, Muranaka T, Nakagawa N, Takagiwa H et al. Strong coupling s-wave superconductivity in MgB2: 11111111B-NMR Study of MgB2 and Al-dopedMgB2. Journal of the Physical Society of Japan. 2002;71(SUPPL.):332-334.
Kotegawa, Hisashi ; Ishida, Kenji ; Kitaoka, Yoshio ; Muranaka, Takahiro ; Nakagawa, Norimasa ; Takagiwa, Hiroyuki ; Akimitsu, Jun. / Strong coupling s-wave superconductivity in MgB2 : 11111111B-NMR Study of MgB2 and Al-dopedMgB2. In: Journal of the Physical Society of Japan. 2002 ; Vol. 71, No. SUPPL. pp. 332-334.
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AB - We have measured nuclear spin-lattice relaxation time, T1 of 11B in MgB2 and Al-doped MgB 2-T1T = const, behavior is observed in the normal state, indicating the absence of strong magnetic correlation. In the superconducting (SC) state of MgBg, 1/T1 shows a tiny coherence peak just below Tg and decreases exponentially with a large SC gap of 2A/kBTc ∼ 5. These results suggest that M gB2 is a strong coupling s-wave superconductor. As Al 3+ is doped into Mg2+ site, 1/T1T which is proportional to the square of the density of states (DOS) decreases. The variation of Tc against the DOS deduced from 1/T1T is fitted by McMillan equation, and the Debye frequency ω and the electron-phonon coupling constant A were estimated as ∼ 700 K and ∼ 0.87, respectively. Both are in good agreement with the values from theoretical works. The high-Tc superconductivity in MgB2 is considered to occur through strong coupling between electrons and high frequency-phonon.

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