Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 41: Heterostructures

HL 41.4: Vortrag

Donnerstag, 30. März 2006, 11:45–12:00, BEY 154

Mesoscopic systems of cold indirect excitons in traps — •Alexei Filinov¹, Yurii Lozovik², Jens Boning¹, and Michael Bonitz¹ — ¹Institut fur Theoretische Physik und Astrophysik, Leibnizstrasse 15, 24098 Kiel — ²Institute of Spectroscopy RAS, Troitsk, 142190, Russia

Experimental studies of cold excitonic gases in heterostructures attract now high interest due to the predicted possibility to observe Bose condensation of indirect excitons. If the excitons have an intrinsic dipole moment produced from specially engineered quantum well bandstructure or an applied electric field, the repulsive dipole-dipole interaction can be a dominant effect which should be taken into account in theoretical considerations. Here we study with Path Integral Monte Carlo (PIMC) simulation recent experimental realizations of indirect excitons in GaAs/AlGaAs coupled QWs [1] and in a single QW in high electric fields influenced in addition by a lateral confinement producing a 3D trap. First, using pre-compiled effective dipole moment, we consider the excitons as 2D bosonic particles. We analyze the possibility to observe an exciton supersolid [2] in mesoscopic systems (N=10..40) and present simulation results for the condensate fraction and the superfluidity. Second, by varying exciton density and temperature we compare these results with full 3D simulations where the excitons are composed from electrons and holes. This comparison allows for a rigorous check of the applicability and limits of the bosonic model of dipoles.

[1] V.Negoita, D.W.Snoke, K.Eberl, Phys. Rev. B 60, 2661 (1999); L.V.Butov et al., Phys.Rev.Lett. 86, 5608 (2001). [2] Yu.E.Lozovik, S.Yu.Volkov, and M.Willander, JETP Lett. 79, 473 (2004).