Abstract
We present electronic structure calculations together with resistivity, susceptibility, and specific heat measurements for to search for the recently contradictorily reported superconductivity and to study related normal-state properties. We ascribe the absence of superconductivity down to 1.5 K for our samples to the generally weak electron-phonon coupling derived from comparison of the calculated and measured specific heat constants. For the and the -point phonons, we derive from the calculated deformation potentials very small electron-phonon couplings for these modes, as opposed to the strong coupling of the mode in probably responsible for its high In comparison to we discuss the origin of the quite different features in the density of states and of the Fermi surfaces. The differences are mainly due to the strong hybridization between and states outside the hexagonal basis plane.
- Received 1 June 2001
DOI:https://doi.org/10.1103/PhysRevB.64.144516
©2001 American Physical Society