Pair breaking in semiclassical singlet small-bipolaron hopping
- Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)
The Holstein-Hubbard model is used to study high-temperature ({ital T}{approx_gt}{ital T}{sub phonon}/3) hopping transport when it is energetically favorable for carriers to pair as singlet small bipolarons. The semiclassical rates for one-electron transfers involving small polarons are found to be much greater than those that only involve small bipolarons. In particular, the most rapid one-electron-transfer processes have a small-polaron hopping to a vacant site and one of a small bipolaron{close_quote}s two carriers jumping onto the site of an adjacent small polaron. As a result, even when most carriers form small bipolarons rather than small polarons, one-electron transfers involving small polarons always dominate the dc conductivity. The energy to thermally generate small polarons from small bipolarons thus contributes to the conductivity{close_quote}s activation energy. This pair-breaking energy also manifests itself in a thermally activated contribution to the system{close_quote}s paramagnetic susceptibility. In addition, the carriers{close_quote} Seebeck coefficient garners a contribution with a temperature dependence that is characterized by the pair-breaking energy. {copyright} {ital 1996 The American Physical Society.}
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 278528
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 3 Vol. 53; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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