Electronic structures of antiperovskite superconductors MgXNi3 (X = B, C, and N) - art. no. 180510

We have investigated electronic structures of a newly discovered antiperovs kite superconductor MgCNi3 and related compounds MgBNi3 and MgNNi3. In MgCN i3, a peak of very narrow and high density of states is located just below the Fermi level. which corresponds to the pi* antibonding state of Ni 3d an d C 2p but with the predominant Ni 3d character. The prominent nesting feat ure is observed in the Gamma -centered electron Fermi surface of an octahed ron-cage-like shape that originates from the 19th band. The estimated super conducting parameters are in reasonable agreement with experiment, suggesti ng that the superconductivity in MgCNi3 is described properly by the conven tional BCS phonon mechanism.