Routes to Room Temperature Superconductivity From A Chemist’s Perspective

While the exact pathway to high-temperature superconductors remains unknown, there are insights into the direction we should pursue. It is well-established that superconductors with higher transition temperatures are typically found near the boundaries of semiconductors, Mott insulators, and magnetism. By studying the properties of elements and compounds under pressure, it becomes clear that the highest transition temperatures tend to occur in elements located on the right side of the periodic table (such as semiconductors or insulators) and on the left side (including hydrogen, hydrides alkali, and alkaline earth metals). Certain crystal structures, such as perovskites and the ThCr₂Si₂ structure, are generally associated with higher transition temperatures. These structures are favorable for both phonon-driven superconductors (e.g., Ba₁-xKxBiO₃, LuNi₂B2C) and unconventional superconductors (e.g., YBa₂Cu₃O₇-x, Ba₁-xKxFe₂As₂). In addition to these structural insights, the role of flatbands in Kagome lattices such as CsV₃Sb₅ and twisted graphene and van Hove singularities has gained attention. Kagome lattices, characterized by their geometric frustration and flatbands, can enhance electronic correlation effects and contribute to unconventional superconductivity. These features, along with valence and electronic instabilities, act as key indicators for Fermi surface nesting, which is linked to the onset of superconductivity at higher temperatures.
This research was supported by the Klaus Tschira Stiftung as part of the SuperC collaboration.