title: Superconductivity in alkali-metal-doped picene.
abstract: Efforts to identify and develop new superconducting materials continue apace, motivated by both fundamental science and the prospects for application. For example, several new superconducting material systems have been developed in the recent past, including calcium-intercalated graphite compounds, boron-doped diamond and-most prominently-iron arsenides such as LaO(1-x)F(x)FeAs (ref. 3). In the case of organic superconductors, however, no new material system with a high superconducting transition temperature (T(c)) has been discovered in the past decade. Here we report that intercalating an alkali metal into picene, a wide-bandgap semiconducting solid hydrocarbon, produces metallic behaviour and superconductivity. Solid potassium-intercalated picene (K(x)picene) shows T(c) values of 7 K and 18 K, depending on the metal content. The drop of magnetization in K(x)picene solids at the transition temperature is sharp (<2 K), similar to the behaviour of Ca-intercalated graphite. The T(c) of 18 K is comparable to that of K-intercalated C(60) (ref. 4). This discovery of superconductivity in K(x)picene shows that organic hydrocarbons are promising candidates for improved T(c) values.
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Ryoji
authors.initials: R
authors.lastname: Mitsuhashi
authors.forename: Yuta
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamanari
authors.forename: Hiroki
authors.initials: H
authors.lastname: Mitamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Kambe
authors.forename: Naoshi
authors.initials: N
authors.lastname: Ikeda
authors.forename: Hideki
authors.initials: H
authors.lastname: Okamoto
authors.forename: Akihiko
authors.initials: A
authors.lastname: Fujiwara
authors.forename: Minoru
authors.initials: M
authors.lastname: Yamaji
authors.forename: Naoko
authors.initials: N
authors.lastname: Kawasaki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Maniwa
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kubozono