Electronic Structure and Electron-Phonon Coupling in the 18K Superconductor Y2C3
Abstract
The electronic structure and electron-phonon coupling in Y2C3 is investigated using density functional calculations. We find that the Fermi level falls in a manifold of mixed character derived from Y d states and antibonding states associated with the C dimers in the structure. Calculations of the electron-phonon coupling for Y and C modes show that the former provide most of the coupling. Modes associated with C-C bond stretching have large matrix elements, but make small contributions to the coupling because of their high phonon frequencies. Substantial electron doping of the C-C antibonding states would yield a large increase in the coupling and critical temperature, perhaps to values comparable to MgB2. However, it seems unlikely that a modification of Y2C3 with much higher filling of the C-C antibonding states can be stabilized.
Cite
@article{arxiv.cond-mat/0404031,
title = {Electronic Structure and Electron-Phonon Coupling in the 18K Superconductor Y2C3},
author = {D. J. Singh and I. I. Mazin},
journal= {arXiv preprint arXiv:cond-mat/0404031},
year = {2009}
}