Cr2AlN and the Search for the Highest Temperature Superconductor in the M2AX Family

We have developed a high-throughput computational method to predict the superconducting transition temperature in stable hexagonal M(2)AX phases, and applied it to all the known possible choices for M (M: Sc, Ti, V, Cr, Mn, Fe, Y, Zr, Nb, Mo, Lu, Hf and Ta). We combine this with the best candidates for A (A: Al, Cu, Ge and Sn ) and X (X: C and N) from our previous work, and predict Tc for 60 M2AX-phase materials, 53 of which have never been studied before. From all of these, we identify Cr2AlN as the best candidate for the highest T-c, and confirm its high T (c) with more detailed density functional theory electron-phonon coupling calculations. Our detailed calculations predict Tc = 14.8 K for Cr2AlN, which is significantly higher than any T-c value known or predicted for any material in the M2AX family to date.