We discover superconductivity in alkali-earth metals doped phenanthrene. The superconducting critical temperatures \emph{T}c are 5.6 K and 5.4 K for Sr1.5phenanthrene and Ba1.5phenanthrene, respectively. The shielding fraction of Ba1.5phenanthrene exceeds 65%. The Raman spectra show 8 cm−1/electron and 7 cm−1/electron downshifts for the mode at 1441 cm−1 due to the charge transfer to organic molecules from the dopants of Ba and Sr. Similar behavior has been observed in A3phenanthrene and A3C60(A = K and Rb). The positive pressure effect in Sr1.5phenanthrene and Ba1.5phenanthrene together with the lower Tc with larger lattice indicates unconventional superconductivity in this organic system.
@article{arxiv.1110.5458,
title = {Superconductivity in alkali-earth metals doped phenanthrene},
author = {X. F. Wang and Y. J. Yan and Z. Gui and R. H. Liu and J. J. Ying and X. G. Luo and X. H. Chen},
journal= {arXiv preprint arXiv:1110.5458},
year = {2012}
}