Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.84: Poster
Wednesday, March 13, 2013, 15:00–19:00, Poster D
Coexistance of phase transition and hysteresis near BEC — •Michael Maennel1, Klaus Morawetz1,2,3, and Pavel Lipavsky4 — 1Muenster University of Applied Sciences, Stegerwaldstrasse 39, 48565 Steinfurt, Germany — 2International Institute of Physics (IIP), Federal University of Rio Grande do Norte, Av. Odilon Gomes de Lima 1722, 59078-400 Natal, Brazil — 3Max Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden, Germany — 4Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 12116 Prague 2, Czech Republic
Multiple phases occurring in a Bose gas with finite-range interaction are investigated. In the vicinity of the onset of Bose-Einstein condensation (BEC) the chemical potential and the pressure show a van-der-Waals like behavior indicating a first-order phase transition although there is no long-range attraction. Furthermore the equation of state becomes multivalued near the BEC transition. For weak interactions described by a hard-sphere (Hartree-Fock) or Popov (Hartree-Fock-Bogoliubov) approximation such a multivalued region can be avoided by the Maxwell construction. However, for strong interaction described by the many-body T-matrix there remains a multivalued region even after a Maxwell construction which is interpreted as a density hysteresis. This unified treatment becomes possible due to the recently found scheme to eliminate self-interaction in the T-matrix approximation which allows to calculate properties below and above the critical temperature.