Superconductivity and electronic structure of perovskite MgCNi3 - art. no.140507

The electronic structure, stability, electron-phonon coupling, and supercon ductivity of the nonoxide perovskite MgCNi3 are studied using density funct ional calculations. The band structure is dominated by a Ni d derived densi ty of states peak just below the Fermi energy, which leads to a moderate St oner enhancement, placing MgCNi3 in the range where spin fluctuations may n oticeably affect transport, specific heat, and superconductivity, providing a mechanism for reconciling various measures of the coupling lambda. Stron g electron-phonon interactions are found for the octahedral rotation mode a nd may exist for other bond angle bending modes. The Fermi surface contains nearly canceling hole and electron sheets that give unusual behavior of tr ansport quantities particularly the thermopower. The results are discussed in relation to the superconductivity of MgCNi3.