2005/03/23 by Thomas E. Weller, Mark Ellerby, Siddharth S. Saxena +2 · 1 citation
Physics and Astronomy · #cond-mat.supr-con
paper · pdf · doi:10.1038/nphys0010
2 Figures. Please see accompanying theoretical manuscript, "Electronic Structure of the Superconducting Graphite Intercalates" by Csanyi et al., cond-mat/0503569
arxiv created 2005/03/23 · arxiv updated 2015/06/25
In this letter we report the discovery of superconductivity in the isostructural graphite intercalation compounds C6Yb and C6Ca, with transition temperatures of 6.5K and 11.5K respectively. A structural characterisation of these compounds shows them to be hexagonal layered systems in the same class as other graphite intercalates. If we assume that all the outer s-electrons are transferred from the intercalant to the graphite sheets, then the charge transfer in these compounds is comparable to other superconducting graphite intercalants such as C8K 1,2 . However, the superconducting transition temperatures of C6Yb and C6Ca are up to two orders of magnitude greater. Interestingly, superconducting upper critical field studies and resistivity measurements suggest that these compounds are significantly more isotropic than pure graphite. This is unexpected as the effect of introducing the intercalant is to move the graphite layer further apart.