Superconductivity and phase stability of potassium-doped biphenyl

Phenyl molecules are proposed as potential high-temperature superconductors due to exhibiting interesting properties. Here, we report the discovery of superconductivity with the critical temperature (T_c) of ∼7.2 Kelvin in potassium (K)-doped biphenyl (C₁₂H₁₀). The dc magnetic susceptibility measurements provide solid evidence for the presence of the Meissner effect in K_xC₁₂H₁₀. The Raman spectra detected bipolaronic characteristics in this superconducting state, which are proposed to account for the electron pairing. Theoretical simulations provided the information of the crystal structure of K_xC₁₂H₁₀. Combining XRD data with formation energy, we suggest that the superconducting phase corresponds to K₂C₁₂H₁₀ or with a small charge fluctuation in a layered structure. The discovery of superconductivity in K-doped biphenyl vastly expands the potential applications in the superconducting field.