Large bipolarons and superconductivity
- Sandia National Labs., Albuquerque, NM (United States)
Superconductivity has long been speculated to result from charge carriers paired as mobile charged bosons. Although the pairing of carriers as small (single-site) bipolarons is known, small bipolarons readily localize. By contrast, large (multi-site) bipolarons, in analogy with large polarons, should be mobile. It is shown that large bipolarons can form in solids with very displaceable ions, e.g., many oxides. Large-polaronic (but not small-polaronic) carriers produce absorption spectra like the carrier-induced absorptions observed in cuprates. Redistribution of the self-trapped carriers of large bipolarons among sites of carriers` molecular orbitals in response to atomic motions lowers phonon frequencies. The dependence of the phonon zero-pont energy on the spatial distribution of large bipolarons produces a phonon-mediated attraction between them. This dynamic quantum-mechanical attraction fosters the condensation of large bipolarons into a liquid. Superconductivity can result when the large-bipolarons` groundstate remains liquid rather than solidifying.
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 136210
- Report Number(s):
- CONF-950144--
- Journal Information:
- Journal of Superconductivity, Journal Name: Journal of Superconductivity Journal Issue: 4 Vol. 8; ISSN 0896-1107; ISSN JOUSEH
- Country of Publication:
- United States
- Language:
- English
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Phonon-mediated attraction between large bipolarons: Condensation to a liquid
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