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TT: Fachverband Tiefe Temperaturen

TT 37: MLT: Poster Session

TT 37.15: Poster

Donnerstag, 25. März 2010, 14:00–18:00, Poster A

Multiple condensed phases in interacting Bose systems — •Michael Männel¹, Klaus Morawetz^2,3, Pavel Lipavský^4,5, and Michael Schreiber¹ — ¹Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany — ²Department Physical Engineering, Münster University of Applied Science, 48565 Steinfurt, Germany — ³International Center of Condensed Matter Physics, University of Brasilia, 70904-970, Brasilia-DF, Brazil — ⁴Institute of Physics, Academy of Sciences, Cukrovarnická 10, 16253 Prague 6, Czech Republic — ⁵Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 12116 Prague 2, Czech Republic

We investigate a Bose gas with finite-range interaction using a scheme to eliminate unphysical processes in the T-matrix approximation. In this way the corrected T-matrix becomes suitable to calculate properties below the critical temperature. For attractive interaction, an Evans-Rashid transition occurs between a quasi-ideal Bose gas and a BCS-like phase with a gaped dispersion. The gap decreases with increasing density and vanishes at a critical density where the single-particle dispersion becomes linear for small momenta indicating Bose-Einstein condensation. The investigation of the pressure shows however, that the mentioned quantum phase transitions might be inaccessible due to a preceding first order transition.