Observation of zero resistivity in K-doped picene.

We report the observation of zero resistivity (p) in a hydrocarbon superconductor, and describe the temperature dependence of p in metal-doped hydrocarbons. The resistivity of K-doped picene (Kx picene) has been recorded from pellet samples in a four-terminal measurement mode. A drop in p is observed below 7 K for K3.1 picene and below 11 K for K3.5picene, which clearly displays zero resistivity. The resistivity drop at 7 K is consistent with the superconducting critical temperature (Tc) obtained from the magnetic susceptibility of the 7 K phase of K3picene, while the drop at 11 K is inconsistent with the Tc's of both the 7 and 18 K phases of K3 picene reported previously. The temperature dependence of p for both samples exhibits granular-metal-like behavior in the normal state. [ABSTRACT FROM AUTHOR]