Metal-insulator transitions and dilute electron and hole doping in the extended Hubbard ([ital d]-[ital p]) model

Journal Article · Tue Nov 15 04:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.13942· OSTI ID:6847000

Kaga, H ^[1]; Saikawa, T ^[2]; Ferraz, A; Brito, P ^[3]

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1. Department of Physics, Niigata University, Niigata 950-21 (Japan) Department of Mathematics, Imperial College, London SW72BZ (United Kingdom)
2. Department of Physics, Niigata University, Niigata 950-21 (Japan)
3. International Centre of Condensed Matter Physics, University of Brasilia, 70919-970 Brasilia, Distrito Federal (Brazil)

Metal-insulator transitions in the three-band extended Hubbard model are studied within the mean-field theory of the Kotliar-Ruckenstein slave-boson formalism. It is shown that the charge-transfer (CT) insulator transition ([Delta][much lt][ital U]) takes place when [ital twice] [ital the] [ital CT[minus]energy] [ital loss] 2[Delta] exceeds eight times the average kinetic-energy gain per site [ital E], contrary to the Mott-Hubbard (MH) transition ([ital U][much lt][Delta]) which occurs when the Coulomb-energy loss [ital U] exceeds [ital E]. The positions of the renormalized [ital d] levels of quasiparticles formed on dilute doping are analyzed. A dilute hole doping into the insulator phase gives rise to several qualitatively different doping regimes, e.g., those with [ital d]-hole or [ital d]-electron doping determined by some simple rules, in which [ital dilute] [ital hole] [ital doping] just inside the boundary always induces [ital d] [ital electron] [ital doping]. We will show that the dilutely hole-doped phase diagram is remarkably symmetric with respect to [ital U] and [Delta], i.e., the MH and CT insulators. The optical conductivity gap [ital E][sub gap] of the MH and CT insulators is interpreted as a jump in the chemical potential [Delta][mu] between dilute electron and hole doping, and is strongly renormalized from the bare Hubbard gap [ital U] or CT gap [Delta] near the metal-insulator boundary, while it is roughly given by the bare gap well inside the insulator phase.

• OSTI ID: 6847000
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:19; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

665410* -- Superconductivity-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BAND THEORY
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CORRELATIONS
CRYSTAL MODELS
D STATES
ELECTRON CORRELATION
ENERGY LEVELS
HIGH-TC SUPERCONDUCTORS
HOLES
HUBBARD MODEL
MATHEMATICAL MODELS
OXIDES
OXYGEN COMPOUNDS
P STATES
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS