Institut für Theoretische Physik, ETH-H?nggerberg, 8093 Zurich, Switzerland, CH
Abstract:
We investigate multiexciton bound states in a semiconducting phase of divalent hexaborides. Due to three degenerate valleys
in both the conduction and valence bands the binding energy of a 6-exciton molecule is greatly enhanced by the shell effect.
The ground state energies of multiexciton molecules are calculated using the density functional formalism. We also show that
charged impurities stabilize multiexciton complexes leading to condensation of localized excitons. These complexes can act
as nucleation centers of local moments.
Received 24 October 2000