Prediction of phonon-mediated superconductivity in new Ti-based M_2AX phases

Abstract

A high-throughput computational method is used to predict 39 new superconductors in the Ti-based M_2AX phases, and the best candidates are then studied in more detail using density functional theory electron–phonon coupling calculations. The detailed calculations agree with the simple predictions, and Ti_2AlX (X: B, C and N) materials are predicted to have higher values of T_c than any currently known hexagonal M_2AX phases. The electronic states at the Fermi level are dominated by the Ti 3d states. The choice of X (X: B, C and N) has a significant impact on the electronic density of states but not on the phonon characteristics. The electron–phonon coupling parameter for Ti_2AlX (X: B, C and N) was determined to be 0.685, 0.743 and 0.775 with a predicted T_c of 7.8 K, 10.8 K and 13.0 K, respectively.