First-order structural phase transitions in a lattice-gas model for YBa sub 2 Cu sub 3 O sub 6+ x
- Department of Physics, Florida State University, Tallahassee, FL (USA) Center for Materials Research and Technology, Florida State University, Tallahassee, FL (USA) Supercomputer Computations Research Institute, Florida State University, Tallahassee, FL (USA)
- Supercomputer Computations Research Institute, Florida State University, Tallahassee, FL (USA)
Recent experiments indicate that the structural phase transitions in the high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 6+{ital x}} may be first order at low temperatures. The oxygen ordering in the Cu-O basal planes of this material may be described by a lattice-gas model introduced by Wille {ital et} {ital al}. B (Phys. Rev. Lett. 60, 1065 (1988)). However, as recent numerical studies show, this model does not exhibit first-order transitions. Here, we extend the model to include weak attractive interactions (2% of the nearest-neighbor interactions) between next-nearest-neighbor oxygen chains, and we study the extended model using transfer-matrix finite-size scaling. We find that these weak interactions produce tricritical points and first-order transitions at low temperatures, which are in good agreement with experiments for the structural order-order phase transitions. Furthermore, we predict a tricritical point and first-order transitions at low temperatures on the order-disorder branch of the phase diagram. We also present the phase diagram.
- DOE Contract Number:
- FC05-85ER25000
- OSTI ID:
- 5997295
- Journal Information:
- Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 42:16; ISSN 0163-1829; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
BASIC INTERACTIONS
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL-PHASE TRANSFORMATIONS
DIAGRAMS
HIGH-TC SUPERCONDUCTORS
INTERACTIONS
MATHEMATICAL MODELS
ORDER-DISORDER TRANSFORMATIONS
OXIDES
OXYGEN COMPOUNDS
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
SCALING LAWS
SUPERCONDUCTORS
TRANSFER MATRIX METHOD
TRANSITION ELEMENT COMPOUNDS
WEAK INTERACTIONS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES