Correlated Superconductivity in a Two-Dimensional Metal-Organic Framework

Metal-Organic Frameworks (MOFs) are composed of metallic clusters linked by organic ligands. While MOFs are often discussed in terms of their use in chemistry applications, the emerging field of Quantum MOFs explores their potential as quantum materials [1]. These materials are typically insulators, but there has been considerable progress in the development of conducting MOFs. Remarkably, the conducting MOF Cu-BHT was found to be superconducting [2], suggesting an unconventional type of superconductivity caused by electronic correlations.

The problem of correlated electrons, as captured by the Hubbard model, is notorious for its analytical intractability. One promising approach involves the use of exactly solvable models, such as the Hatsugai-Kohmoto (HK) model [3]. Recent work has demonstrated that the HK model is the minimal model that breaks the particle-hole symmetry of a Fermi liquid and falls within the same universality class as the Hubbard model [4]. This makes it an ideal framework for studying the universal properties of correlated systems, including correlated superconductors. This step was performed in [5] for an s-wave spin singulett pairing. We extend these findings to more complex pairing symmetries, including multiband superconductivity, in order to account for materials with more intricate electronic structures, such as Cu-BHT.

[1] Z. Huang and M. Geilhufe Small Sci. 4 2400161 (2024)

[2] T. Takenaka et al. Sci. Adv. 7 12 eabf3996 (2021)

[3] Y. Hatsugai and M. Kohmoto J. Phys. Soc. Japan 61 6 2056 (1992)

[4] E. Huang et al. Nat. Phys. 18 5 511 (2022)

[5] P. Phillips et al. Nat. Phys. 16 12 1175 (2020)