Correlation Effects in the Triangular Lattice Single-band System Li_xNbO_2
Abstract
Superconductivity in hole-doped Li_xNbO_2 has been reported with T_c ~ 5 K in the range 0.45 < x < 0.8. The electronic structure is based on a two-dimensional triangular Nb lattice. The strong trigonal crystal field results in a single Nb d(z^2) band isolated within a wide gap, leading to a single-band triangular lattice system. The isolated, partially filled band has a width W=1.5 eV with dominant second neighbor hopping. To identify possible correlation effects, we apply DMFT(QMC) using on-site Coulomb repulsion U=0-3 eV, and check selected results using determinant QMC. For U as small as 1 eV, the single particle spectrum displays a robust lower Hubbard band, suggesting the importance of correlation effects in Li_xNbO_2 even for U < W. At half-filling (x=0), a Mott transition occurs at U_c ~ 1.5 eV. Coupling between the O A_g phonon displacement and correlation effects is assessed.
Cite
@article{arxiv.0707.4653,
title = {Correlation Effects in the Triangular Lattice Single-band System Li_xNbO_2},
author = {K. -W. Lee and J. Kunes and R. T. Scalettar and W. E. Pickett},
journal= {arXiv preprint arXiv:0707.4653},
year = {2011}
}
Comments
9 pages, 7 figures