Europhys. Lett, 48 (3), pp. 299-305 (1999)
Superfluidity of indirect biexcitons in superlattices
Yu. E. Lozovik 1, O. L. Berman 1 and M. Willander 2
1 Institute of Spectroscopy, Russian Academy of Sciences
Troitsk, 142092, Moscow region, Russia
2 Goteborg University, Chalmers University of Technology
S-41296, Goteborg, Sweden
(received 6 April 1999; accepted in final form 2 September 1999)
- Low-dimensional structures (superlattices, quantum well structures, multilayers):
structure and nonelectronic properties.
PACS. 71.35Lk - Collective effects (Bose effects, phase space filling, and excitonic phase transitions).
PACS. 73.20Dx - Electron states in low-dimensional structures (superlattices, quantum well structures and multilayers).
The instability of the ground state of a system of two-dimensional spatially indirect excitons interacting in a slab of superlattice with alternating electron and hole layers is established. The stable system of spatially indirect quasi-two-dimensional biexcitons, consisting in spatially indirect excitons with opposite directed dipole moments is considered. The radius and the binding energy of spatially indirect biexciton are calculated. The collective spectrum of a low-density system of two-dimensional spatially indirect biexcitons, interacting as electrical quadrupoles, is studied. The density of the superfluid component and the Kosterlitz-Thouless phase transition to the superfluid state in this system are analyzed.
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