Start Over

Evidence for Gap Anisotropy inCaC6from Directional Point-Contact Spectroscopy

Authors :: Sandro Massidda
Renato Gonnelli
Gianni Profeta
Antonio Sanna
Mauro Tortello
Jun Sung Kim
Giovanni Ummarino
D. Delaude
R. K. Kremer
Dario Daghero
V. A. Stepanov
Source :: Physical review letters, info:cnr-pdr/source/autori:Gonnelli, RS; Daghero, D; Delaude, D; Tortello, M; Ummarino, GA; Stepanov, VA; Kim, JS; Kremer, RK; Sanna, A; Profeta, G; Massidda, S/titolo:Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy/doi:10.1103%2FPhysRevLett.100.207004/rivista:Physical review letters (Print)/anno:2008/pagina_da:207004/pagina_a:/intervallo_pagine:207004/volume:100
Publication Year :: 2008
Publisher :: American Physical Society (APS), 2008.
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.<br />Comment: 4 pages, 4 color eps figures. New results at 400 mK added; figures and discussion modified accordingly. Phys. Rev. Lett., accepted