Break-junction tunneling spectra of MgB2: Influence of boron quality

R. A. Ribeiro, T. Ekino, T. Takasaki, T. Takabatake, J. Akimitsu

Research output: Contribution to journalConference article

2 Citations (Scopus)

Abstract

Tunneling spectra of a superconductor-insulator-superconductor (SIS) junction formed by the break-junction technique have been carried out for two different boron quality MgB2 samples. One is a polycrystalline MgB2 pellet (RRR ≈ 4) and the other is a high purity MgB 2 wire (RRR ≈ 25) of approximately 150 μm in diameter. Both samples exhibit a multiple-gap feature, which can be expressed by the correlated two-gap model. From the conductance fitting at 4.2 K, the pellet gap parameters are ΔS = 2.2 ± 0.3 meV, ΔM = 6.0 ± 1.5 meV and ΔL = 10 meV, whereas the only clear and very reproducible gap in the wires is the small gap at ΔS = 2.5 ± 0.1 meV. The wires show almost constant values for the fitting parameters of the two-gap model, in contrast with the pellets that show a large variation.

Original languageEnglish
Pages (from-to)450-453
Number of pages4
JournalPhysica C: Superconductivity and its applications
Volume426-431
Issue numberI
DOIs
Publication statusPublished - Oct 1 2005
Externally publishedYes
EventProceedings of the 17th International Symposium on Superconductivity (ISS 2004) Advances in Supeconductivity -
Duration: Nov 23 2004Nov 25 2004

Keywords

  • Break junction
  • MgB
  • Superconducting gap
  • 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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