Hamburg 2009 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 15: Poster I

A 15.34: Poster

Dienstag, 3. März 2009, 16:30–19:00, VMP 9 Poster

Berezinskii-Kosterlitz-Thouless transition in two-dimensional dipole systems — •Alexey Filinov^1,3, Nikolay Prokof’ev², Michael Bonitz¹, and Yurii Lozovik³ — ¹Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität, Leibnizstr. 15, D-24098 Kiel, Germany — ²Department of Physics, University of Massacusetts, Amherst, Massachusetts 01003, USA — ³Institute of Spectroscopy of the Russian Academy of Sciences, Troitsk, Russia

Dilute dipole gases of polar molecules and indirect excitons in quantum wells are of increasing interest in recent experimental realizations [1,2], since they allow to realize and control correlations and quantum degeneracy effects. Using path integral Monte Carlo we investigate the normal-superfluid transition in a system of 2D bosonic dipoles which models such experiments in the full temperature-density plane. The critical temperature, superfluid fraction, thermodynamic sound speed and compressibility have been evaluated for different dipole coupling strengths/densities. For indirect excitons at high densities the dipole approximation becomes invalid. We, therefore, take into account the internal exciton structure and derive new effective interaction which crucially effects the phase diagram at high densities.

[1] J.M. Sage at al., Phys. Rev. 94, 203001 (2005); D. Wang at al., Phys. Rev. 93, 243005 (2004). [2] Timofeev V et al 2007 J. Phys: Cond. Matt. 19 295209.