Symmetries and mean-field phases of the extended Hubbard model

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.52.3662· OSTI ID:83940

Eriksson, A B; Einarsson, T; Oestlund, S ^[1]

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1. Institute of Theoretical Physics, Chalmers University of Technology Gothenburg University, S-41296 Goeteborg (Sweden)

The two-dimensional extended Hubbard model that includes a nearest-neighbor Heisenberg interaction is studied using a mean-field theory where quasiparticles are defined by an U(8) group of canonical transformations permitting both broken gauge, spin, and sublattice symmetry. The theory is further extended to incorporate a possible twist in the spin-quantization axis, so that the competition between superconductivity, charge density waves, and Neel and spiral antiferromagnetic order can be monitored within one single theory. Our results for positive Hubbard {ital U} and Heisenberg exchange {ital J} suggest that antiferromagnetic ordering dominates close to half-filling, while spiral states and {ital d}-wave superconductivity compete when doping is introduced. For moderate values of {ital J}, we find a phase diagram where a phase transition occurs from an antiferromagnet to a {ital d}-wave superconductor as doping is increased. A narrow region of ({ital s}+{ital id})-wave superconductor is found for some values of {ital J} and {ital U}.

• OSTI ID: 83940
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 5 Vol. 52; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ANTIFERROMAGNETISM
D WAVES
HEISENBERG MODEL
HUBBARD MODEL
MEAN-FIELD THEORY
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
QUASI PARTICLES
SUPERCONDUCTIVITY
TWO-DIMENSIONAL CALCULATIONS