Phys. Rev. Lett. 100, 207004 (2008) [4 pages]Evidence for Gap Anisotropy in CaC6 from Directional Point-Contact SpectroscopyReceived 7 August 2007; published 20 May 2008 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 Δ(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. © 2008 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.100.207004
DOI:
10.1103/PhysRevLett.100.207004
PACS:
74.50.+r, 74.45.+c, 74.70.Ad
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