Structure and superconductivity in LnNi(2)B(2)C: comparison of calculationand experiment

The experimental relation between the superconducting transition temperatur e (T-c) and lattice size for the lanthanide nickel borocarbides is clarifie d. The electronic density of states (DOS) at the Fermi energy is calculated by the LMTO method for selected non-magnetic lanthanides. The T-c and the DOS are both shown to scale in the same way with a structural parameter tha t characterizes the bond angle in the NiB4 tetrahedra. The results strongly support arguments that the suppression of superconductivity on going from smaller to larger lanthanides in the quaternary nickel borocarbides is stru cturally driven. A structure-T-c relationship of this type is unusual for i ntermetallic superconductors. (C) 2001 Elsevier Science Ltd. All rights res erved.