LuNi2B2C: A novel Ni-based strong-coupling superconductor

The surprising recent discovery of superconductivity up to ${\mathit{T}}_{\mathit{c}}$=23 K in Ni- and Pd-based rare-earth borocarbides raises the question of whether or not these materials constitute a new class of high temperature superconductors. For ${\mathrm{LuNi}}_2$ ${\mathrm{B}}_2$C, with ${\mathit{T}}_{\mathit{c}}$=16.6 K and a (known) layered crystal structure I4/mmm, electronic structure calculations indicate that it is a strongly 3D metal with all atoms contributing to the metallic character, completely unlike the cuprate HTS. Incorporating resistivity data we deduce a very strong electron-phonon coupling ${\lambda }_{\mathrm{tr}}$=2.6, which we relate to an unusual combination of states at the Fermi level and substantial contributions from the vibrations of the light atoms.