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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.83: Poster
Wednesday, March 13, 2013, 15:00–19:00, Poster D
Electron-hole pair condensation at the semimetal-semiconductor transition: a BCS-BEC crossover scenario — •Holger Fehske1, Bernd Zenker1, Franz Xaver Bronold1, Dieter Ihle2, Van-Nham Phan3, and Klaus Becker4 — 1Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, D-17487 Greifswald — 2Institut für Theoretische Physik, Universität Leipzig, D-04109 Leipzig — 3Institute of Physics, Vietnamese Academy of Science and Technology, PO Box 429, 10000 Hanoi — 4Institut für Theoretische Physik, Technische Universität Dresden, D-01062 Dresden
We act on the suggestion that an excitonic insulator state might separate - at very low temperatures - a semimetal from a semiconductor and ask for the nature of these transitions. Based on a detailed analysis of electron-hole pairing in the extended Falicov-Kimball model, we show that tuning the Coulomb attraction between both species, a continuous crossover between a BCS-like transition of Cooper-type pairs and a Bose-Einstein condensation of preformed tightly-bound excitons might be achieved in a solid-state system. The precursor of this crossover in the normal state might cause the transport anomalies observed in several strongly correlated mixed-valence compounds.