Potential for High-Tc Superconductivity in Triazine Crystals

We demonstrate the potential for high-Tc superconductivity in electrically charged crystals of 1,3,5-triazine. Identification of 1,3,5-triazine as a possible organic superconductor was achieved through a multi-step approach which incrementally builds up from low cost isolated molecules to physically realizable crystals. In isolated molecules of 1,3,5-triazine, an onset of strong electron-phonon coupling is found to arise from a breaking of the three-fold rotational symmetry. Strong electron-phonon coupling persists as the complexity of the system is increased from isolated molecules to single molecule unit cell crystals to four molecule unit cell crystals. Tc was computed for two different crystal structures based on the experimentally observed structure: a C2/c structure and a structure obtained via crystal structure prediction. Superconducting properties depend on both the charge of the crystal and the polymorph. A maximum Tc of 127 K is found in a charged 1,3,5-triazine crystal on the verge of instability through evaluation of the Eliashberg gap function. The incremental approach demonstrated here can be more broadly applied in the search for organic superconductors.