LONG-LIVED CHARGED MULTIPLE-EXCITON COMPLEXES IN STRONG MAGNETIC-FIELDS

We consider the charged exciton complexes of an ideal two-dimensional electron-hole system in the limit of strong magnetic fields. A series of charged multiple-exciton states is identified and variational and f inite-size exact-diagonalization calculations are used to estimate the ir binding energies. We find that, because of a hidden symmetry, bound states of excitons and an additional electron cannot be created by di rect optical absorption and, once created, have an infinite optical re combination lifetime. We also estimate the optical recombination rates when electron and hole layers are displaced and the hidden symmetry i s violated.