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Journal of Superconductivity

, Volume 12, Issue 3, pp 519–523 | Cite as

STM Spectroscopy on Anisotropic Superconductors

  • K. Ichimura
  • T. Arai
  • K. Nomura
  • S. Takasaki
  • J. Yamada
  • S. Nakatsuji
  • H. Anzai
  • T. Nakamura
  • T. Takahashi
  • B. Hilti
  • J. S. Zambounis
Article

Abstract

The superconducting phase of organic superconductors κ-(BEDT-TTF)2Cu(NCS)2 and (MDT-TTF)2AuI2 was investigated by the electron tunneling spectroscopy using low temperature STM. The tunneling differential conductance at the lateral surface of κ-(BEDT-TTF)2Cu(NCS)2 varies its shape depending on the tip direction. The in-plane anisotropy of the conductance is well explained by the d-wave symmetry with line nodes along the direction 45° from the c-axis. For (MDT-TTF)2AuI2, the tunneling conductance at T = 1.4 K shows the superconducting energy gap structure clearly. The finite conductance inside the gap edge suggests the gap anisotropy. The tunneling spectrum is explained by the d-wave pairing. The obtained gap Δ0 = 2 meV (2Δ0/kT c = 12) is larger than that of the weak coupling limit. The pseudogap structure is observed near T c .

STM electron tunneling organic superconductors pairing symmetry 

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Copyright information

© Kluwer Academic/Plenum Publishers 1999

Authors and Affiliations

  • K. Ichimura
    • 1
  • T. Arai
    • 1
  • K. Nomura
    • 1
  • S. Takasaki
    • 2
  • J. Yamada
    • 2
  • S. Nakatsuji
    • 2
  • H. Anzai
    • 2
  • T. Nakamura
    • 3
  • T. Takahashi
    • 3
  • B. Hilti
    • 4
  • J. S. Zambounis
    • 4
  1. 1.Hokkaido UniversitySapporoJapan
  2. 2.Department of Material ScienceHimeji Institute of TechnologyHyogoJapan
  3. 3.Department of PhysicsGakushuin UniversityTokyoJapan
  4. 4.Central Research LaboratoriesCiba-Geigy AGBaselSwitzerland

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