Superconducting energy gap distribution in c-axis oriented MgB2 thin film from point contact study

  • Yu. G. Naidyuk
  • I. K. Yanson
  • L. V. Tyutrina
  • N. L. Bobrov
  • P. N. Chubov
  • W. N. Kang
  • Hyeong-Jin Kim
  • Eun-Mi Choi
  • Sung-Ik Lee
Condensed Matter

DOI: 10.1134/1.1478521

Cite this article as:
Naidyuk, Y.G., Yanson, I.K., Tyutrina, L.V. et al. Jetp Lett. (2002) 75: 238. doi:10.1134/1.1478521

Abstract

We have analyzed about a hundred voltage-dependent differential resistance dV/dI(V) curves of metallic point contacts between c-axis-oriented MgB2 thin film and Ag, which exhibit clear Andreev reflection features connected with the superconducting gap. About one half of the curves show the presence of a second larger gap. The histogram of the double gap distribution reveals distinct maxima at 2.4 and 7 meV, while curves with single-gap features result in a more broad maximum at 3.5 meV. The double-gap distribution is in qualitative agreement with the distribution of gap values over the Fermi surface calculated by H. J. Choi et al. (cond-mat/0111183). The data unequivocally show the presence of two gaps: ΔS=2.45±0.15 meV and ΔL=7.0±0.45 meV in MgB2 with the gap ratio ΔLS=2.85±0.15. Our observations further prove a widely discussed multigap scenario for MgB2, where two distinct gaps are seen in the clean limit, while a single averaged gap is present in the dirty one.

PACS numbers

73.40.Jn 74.76.Db 74.80.Fp 

Copyright information

© MAIK "Nauka/Interperiodica" 2002

Authors and Affiliations

  • Yu. G. Naidyuk
    • 1
  • I. K. Yanson
    • 1
  • L. V. Tyutrina
    • 1
  • N. L. Bobrov
    • 1
  • P. N. Chubov
    • 1
  • W. N. Kang
    • 2
  • Hyeong-Jin Kim
    • 2
  • Eun-Mi Choi
    • 2
  • Sung-Ik Lee
    • 2
  1. 1.Verkin Institute for Low Temperature Physics and EngineeringNational Academy of Sciences of UkraineKharkivUkraine
  2. 2.National Creative Research Initiative Center for Superconductivity, Department of PhysicsPohang University of Science and TechnologyPohangSouth Korea

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