The impurity ion off-center behavior induced by a localized vibronic Frenkel exciton in a soft-mode crystal
| Autor: | E. A. Ruzanova, V. S. Vikhnin |
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| Rok vydání: | 2009 |
| Předmět: |
Condensed Matter::Quantum Gases
Condensed matter physics Condensed Matter::Other Chemistry Phonon Exciton Jahn–Teller effect General Chemistry Soft modes Electron Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Condensed Matter Physics Ion Condensed Matter::Materials Science Condensed Matter::Strongly Correlated Electrons General Materials Science Excitation Biexciton |
| Zdroj: | Crystallography Reports. 54:504-508 |
| ISSN: | 1562-689X 1063-7745 |
| DOI: | 10.1134/s1063774509030213 |
| Popis: | The 3d-4p Frenkel exciton localized at a Mn4+ impurity ion in BaTiO3 is considered. The electron and hole of this exciton are correlated, degenerate, and involved in the pair Jahn-Teller effect. Such an exciton is characterized by the significant contribution of indirect electron-hole attraction through lattice (in particular, soft) vibrations to the coupling energy, which is comparable with the Coulomb attraction. Thus, the exciton under consideration is both Coulomb and vibronic excitation. The vibronic contribution increases when approaching the point of soft phonon condensation. It is shown that a vibronic Frenkel exciton allows the off-center behavior of an impurity ion, which is significantly enhanced when approaching the point of soft phonon condensation. As a result, the vibronic Frenkel exciton is a low-lying excitation. |
| Databáze: | OpenAIRE |
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