Europhys. Lett.
Volume 75, Number 3, August 2006
Page(s) 461 - 467
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 30 June 2006
Europhys. Lett., 75 (3), pp. 461-467 (2006)
DOI: 10.1209/epl/i2006-10125-6

Resonating bipolarons

Julius Ranninger1 and Alfonso Romano2, 3

1  Centre de Recherches sur les Très Basses Températures, Laboratoire Associé à l'Université Joseph Fourier, Centre National de la Recherche Scientifique BP 166, F-38042 Grenoble Cédex 9, France
2  Dipartimento di Fisica "E. R. Caianiello", Università di Salerno I-84081 Baronissi (Salerno), Italy
3  Laboratorio Regionale SuperMat, CNR-INFM - Salerno, Italy

received 7 March 2006; accepted in final form 9 June 2006
published online 30 June 2006

Electrons coupled to local lattice deformations end up in self-trapped localized molecular states involving their binding into bipolarons when the coupling is stronger than a certain critical value. Below that value they exist as essentially itinerant electrons. We propose that the abrupt crossover between the two regimes can be described by resonant pairing similar to the Feshbach resonance in binary atomic collision processes. Given the intrinsically local nature of the exchange of pairs of itinerant electrons and localized bipolarons, we demonstrate the occurrence of such a resonance on a finite-size cluster made out of metallic atoms surrounding a polaronic ligand center.

71.10.Li - Excited states and pairing interactions in model systems.
71.38.-k - Polarons and electron-phonon interactions.
33.15.Vb - Correlation times in molecular dynamics.

© EDP Sciences 2006