Correlation effects in the triangular lattice single-band system LixNbO2

Article

关键词: ELECTRONIC-STRUCTURE;    PHYSICAL-PROPERTIES;    SUPERCONDUCTIVITY;    TRANSITION;    NBO2;   

DOI  :  10.1103/PhysRevB.76.144513

来源: SCIE

【 摘 要 】

Superconductivity in hole-doped LixNbO2 has been reported with T-c approximate to 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 dynamical mean field theory and quantum Monte Carlo (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 LixNbO2 even for U <= W. At half-filling (x=0), a Mott transition occurs at U-c approximate to 1.5 eV. Coupling between the O A(g) phonon displacement and correlation effects is assessed.

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