Valence-skipping and negative-U in the d-band from repulsive local Coulomb interaction

Article

关键词: HARTREE-FOCK;    OXIDES;    MODEL;   

DOI  :  10.1103/PhysRevB.90.155108

来源: SCIE

【 摘 要 】

We show that repulsive local Coulomb interaction alone can drive valence-skipping charge disproportionation in the degenerate d-band, resulting in effective negative-U. This effect is shown to originate from anisotropic orbital-multipole scattering, and it occurs only for d(1), d(4), d(6), and d(9) fillings (and their immediate surroundings). Explicit boundaries for valence-skipping are derived, and the paramagnetic phase diagram for d(4) and d(6) is calculated. We also establish that the valence-skipping metal is very different, in terms of its local valence distribution, compared to the atomiclike Hund's metal. These findings explain why transition-metal compounds with the aforementioned d-band fillings are more prone to valence-skipping charge order and anomalous superconductivity.

【 授权许可】

Free