Fate of the excitonic insulator in the presence of phonons
- Zenker, B. Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, Germany
- Fehske, H. Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, Germany
- Beck, Hans Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, Switzerland
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11.11.2014
Published in:
- Physical Review B. - 2014, vol. 90, no. 19, p. 195118
English
The influence of phonons on the formation of the excitonic insulator has hardly been analyzed so far. Recent experiments on Ta2NiSe5,1T−TiSe2, and TmSe0.45Te0.55, being candidates for realizing the excitonic-insulator state, suggest, however, that the underlying lattice plays a significant role. Employing the Kadanoff-Baym approach we address this issue theoretically. We show that owing to the electron-phonon coupling a static lattice distortion may arise at the excitonic instability. Most importantly such a distortion will destroy the acoustic phase mode being present if the electron-hole pairing and condensation is exclusively driven by the Coulomb interaction. The absence of off-diagonal long-range order, when lattice degrees of freedom are involved, challenges that excitons in these materials form a superfluid condensate of Bose particles or Cooper pairs composed of electrons and holes.
- Faculty
- Faculté des sciences et de médecine
- Department
- Département de Physique
- Language
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- English
- Classification
- Physics
- License
- License undefined
- Identifiers
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- RERO DOC 234285
- DOI 10.1103/PhysRevB.90.195118
- Persistent URL
- https://folia.unifr.ch/unifr/documents/304220
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