Density Of Superfluid Component Research Articles

Instability of dipole magnetoexcitons in quantum wells' and graphene superlattices

We propose the Bose–Einstein condensation and superfluidity of quasi-two-dimensional spatially indirect magnetobiexcitons in a slab of superlattice with alternating electron and hole layers consisting from the semiconducting quantum wells (QWs) and graphene superlattice in high magnetic field. For this system the instability of the ground state of interacting two-dimensional indirect magnetoexcitons in a slab of superlattice with alternating electron and hole layers in high magnetic field is found. The density of superfluid component n s ( T ) and the temperature of the Kosterlitz–Thouless phase transition to the superfluid state in the system of two-dimensional indirect magnetobiexcitons, interacting as electrical quadrupoles, are obtained for both QW and graphene realizations.

Stability of indirect biexcitons in superlattices

The unstability of the ground state of the system of interacting two-dimensional indirect excitons in a slab of superlattice with alternating electron and hole layers is established. The stable system of indirect quasi-two-dimensional biexcitons, consisting from indirect excitons with opposite directed dipole moments is considered. The radius and the binding energy of indirect biexciton are calculated. Collective spectrum of low-density system of two-dimensional indirect biexcitons, interacting as electrical quadrupoles, is derived. The density of superfluid component n s( T) and the temperature of the Kosterlitz–Thouless phase transition to the superfluid state in this system are obtained. We assume there are no external fields applied to the slab of superlattice under consideration.