Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy

R. S. Gonnelli; D. Daghero; D. Delaude; M. Tortello; G. A. Ummarino; V. A. Stepanov; J. S. Kim; R. K. Kremer; A. Sanna; G. Profeta; S. Massidda

doi:10.1103/PhysRevLett.100.207004

Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy

Superconductivity 2009-06-04 v2

Authors: R. S. Gonnelli , D. Daghero , D. Delaude , M. Tortello , G. A. Ummarino , V. A. Stepanov , J. S. Kim , R. K. Kremer , A. Sanna , G. Profeta , S. Massidda

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Abstract

We present the first results of directional point-contact spectroscopy in high quality CaC6 samples both along the ab plane and in the c-axis direction. The superconducting order parameter \Delta(0), obtained by fitting the Andreev-reflection (AR) conductance curves at temperatures down to 400 mK with the single-band 3D Blonder-Tinkham-Klapwijk model, presents two different distributions in the two directions of the main current injection, peaked at 1.35 and 1.71 meV, respectively. By ab-initio calculations of the AR conductance spectra, we show that the experimental results are in good agreement with the recent predictions of gap anisotropy in CaC6.

Keywords

CaC6 gap anisotropy point-contact spectroscopy Andreev reflection superconducting order parameter Blonder-Tinkham-Klapwijk model ab-initio calculations

Cite

@article{arxiv.0708.0921,
  title  = {Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy},
  author = {R. S. Gonnelli and D. Daghero and D. Delaude and M. Tortello and G. A. Ummarino and V. A. Stepanov and J. S. Kim and R. K. Kremer and A. Sanna and G. Profeta and S. Massidda},
  journal= {arXiv preprint arXiv:0708.0921},
  year   = {2009}
}

Comments

4 pages, 4 color eps figures. New results at 400 mK added; figures and discussion modified accordingly. Phys. Rev. Lett., accepted

Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy

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