Perspectives of the disproportionation driven superconductivity in strongly correlated 3d compounds

摘要: Disproportionation in 3d compounds can give rise to an unconventional electron-hole Bose liquid with a very rich phase diagram from metal, charge ordering insulator inhomogeneous superfluid. Optimal conditions for the disproportionation driven high-T_c superconductivity are shown realize only several Jahn-Teller d^n configurations that permit formation of well defined local composite bosons. These high-spin d^4, low-spin d^7, and d^9 given octahedral crystal field, d^1, d^6 tetrahedral field. The reaction has peculiar anti-Jahn- Teller character lifting bare orbital degeneracy. Superconductivity d^4 systems at variance implies unavoidable coexistence spin-triplet bosons magnetic lattice. We argue observed quasi-2D cuprates tetragonally distorted CuO_6 octahedra iron-based layered pnictides/chalcogenides tetrahedrally coordinated Fe^2+ ions be key argument supporting scenario is work these compounds.