A Landau theoretical study of La2−x (Sr,Ba) xCuO4−y: Structural phase transitions and related elastic properties
| Autor: | T. Lægreid, Wu Ting, K. Fossheim |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Coupling constant
chemistry.chemical_classification High-temperature superconductivity Condensed matter physics Young's modulus General Chemistry Condensed Matter Physics Landau theory law.invention symbols.namesake chemistry law Phase (matter) Materials Chemistry symbols Elastic modulus Inorganic compound Phase diagram |
| Zdroj: | Solid State Communications. 75:727-730 |
| ISSN: | 0038-1098 |
| DOI: | 10.1016/0038-1098(90)90235-4 |
| Popis: | A Landau free energy suitable for describing the structural phase transitions in La 2−x (Sr,Ba) x CuO 4−y is derived by means of group theory. It is demonstrated that the coupling energy due to the interaction between stress field and structural order parameter must include a term bilinear in two order parameter components. The structural phase transitions (SPTs) in La 2−x (Sr,Ba) x CuO 4−y are discussed. The calculations suggest that several SPTs may occur in these materials. The elastic moduli of lower-symmetry phases are determined and a phase diagram is given. The changes in the elastic moduli C 11 ,C 12 , C 13 , and C 33 caused by the transition from the 14/mmm phase to the Cmca phase in La 2−x Sr x CuO 4 are evaluated and three coupling constants are determined quantitatively on the basis of the available experimental results. |
| Databáze: | OpenAIRE |
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