Prediction of phonon-mediated superconductivity in two-dimensional Mo2B2

Superconductivity has attracted much interest in two-dimensional (2D) compounds because of their application in constructing nano-superconducting devices. Based on the crystal structure prediction method and first-principles calculations, we obtain two new 2D molybdenum boride structures of tetr- and tri-Mo2B2. Then, we calculate their electronic structures, phonon spectra, electron-phonon coupling (EPC), and superconducting properties. The results show that both tetr- and tri-Mo2B2 are intrinsic phonon-mediated superconductors with superconducting transition temperatures (T-c) of 3.9 and 0.2 K, respectively. We demonstrate that the EPC is mainly from the low-frequency phonon vibrations of Mo atoms. Our findings will enrich 2D superconducting materials and stimulate more efforts in this field.