Scanning tunneling spectroscopy and break junction spectroscopy on iron-oxypnictide superconductor NdFeAs(O0.9F0.1)

A. Sugimoto, T. Ekino, R. Ukita, K. Shohara, H. Okabe, J. Akimitsu, A. M. Gabovich

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Iron-oxypnictide superconductor NdFeAs(O0.9F0.1) was studied using both low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and tunnel break junction (BJ) methods. STM topography showed granular and spot structures with a typical size of several nanometers, most probably governed by fluorine atom distribution. The majority of STS conductance, G, versus voltage, V, curves revealed V-shaped structures, whereas some of G(V) dependences possessed coherent gap peaks or kinks at gap energies. At the same time, G(V) dependences obtained by the BJ technique showed clear-cut coherence peaks with peak-to-peak distances Vpp = 4Δ/e ∼ 25 mV at 4.2 K, where Δ is the superconducting energy gap, e > 0 is the elementary charge. This yields Δ(0) = 6-7 meV, so that the ratio 2Δ(0)/k BTc is about 3-4, kB being the Boltzmann constant. This value is consistent with the conventional weak-coupling s-wave Bardeen-Cooper-Schrieffer theory.

Original languageEnglish
Pages (from-to)1070-1072
Number of pages3
JournalPhysica C: Superconductivity and its applications
Volume470
Issue number20
DOIs
Publication statusPublished - Nov 1 2010
Externally publishedYes

Keywords

  • Iron-pnictide superconductor
  • STM
  • Tunneling spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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