Superconductivity near phase separation in models of correlated electrons

Journal Article · Tue Feb 01 04:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.3548· OSTI ID:5358986

Dagotto, E ^[1]; Riera, J ^[2]; Chen, Y C ^[3]; Moreo, A; Nazarenko, A ^[1]; Alcaraz, F ^[4]; Ortolani, F ^[5]

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1. Department of Physics, National High Magnetic Field Laboratory, MARTECH, Florida State University, Tallahassee, Florida 32306 (United States)
2. Center for Computationally Intensive Physics, Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6373 (United States) Department of Physics Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)
3. Department of Physics, National Tsing Hua University, Hsinchu 30043, Taiwan (Taiwan, Province of China)
4. Departamento de Fisica, Universidade Federal de Sao Carlos, CP 616, 13560, Sao Carlos, SP (Brazil)
5. Dipartimento di Fisica, Instituto Nazionale di Fisica Nucleare, Universita di Bologna, via Irnerio 46, I-40126 Bologna (Italy)

Numerical and analytical studies of several models of correlated electrons are discussed. Based on exact diagonalization and variational Monte Carlo techniques, we have found indications that the two-dimensional [ital t]-[ital J] model superconducts near phase separation in the regime of quarter-filling density, in agreement with previous results reported by Dagotto and Riera [Phys. Rev. Lett. 70, 682 (1993)]. At this density the dominant channel is [ital d][sub [ital x]][sup 2][minus][ital y][sup 2], but a transiton to [ital s]-wave superconductivity is observed decreasing the electronic density. In addition, the one-band [ital t]-[ital U]-[ital V] model has also been studied using a mean-field approximation. An interesting region of [ital d][sub [ital x]][sup 2][minus][ital y][sup 2] superconductivity near phase separation is observed in the phase diagram, and its implications for recent self-consistent studies of [ital d]-wave condensates in the context of the high-[ital T][sub [ital c]] cuprates are briefly discussed. Finally, the two-band Hubbard model on a chain is also analyzed. Superconducting correlations near phase separation exist in this model, as it occurs in the [ital t]-[ital J] model. Based on these nontrivial examples it is conjectured that electronic models tend to have superconducting phases in the vicinity of phase separation, and this regime of parameter space should be explored first when a new model for superconductivity is proposed. Reciprocally, if it is established that a model does not phase separate, even in an extended parameter space, then we believe that its chances of presenting a superconducting phase are considerably reduced.

• DOE Contract Number: AC05-84OR21400; FG05-87ER40376
• OSTI ID: 5358986
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 49:5; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
360207* -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ANTIFERROMAGNETISM
CALCULATION METHODS
COPPER COMPOUNDS
CORRELATIONS
CRYSTAL MODELS
CUPRATES
D WAVES
ELECTRON CORRELATION
HIGH-TC SUPERCONDUCTORS
HUBBARD MODEL
MAGNETISM
MATHEMATICAL MODELS
MONTE CARLO METHOD
OXYGEN COMPOUNDS
PARTIAL WAVES
S WAVES
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS