Observation of zero resistivity in K-doped picene

We report the observation of zero resistivity ({ρ}) in a hydrocarbon superconductor, and describe the temperature dependence of {ρ} in metal-doped hydrocarbons. The resistivity of K-doped picene (Kₓpicene) has been recorded from pellet samples in a four-terminal measurement mode. A drop in ρ is observed below 7 K for K3.1picene 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 K₃picene reported previously. The temperature dependence of {ρ} for both samples exhibits granular-metal-like behavior in the normal state.