Magnetic Properties of Nonmagnetic Nanostructures: Dangling Bond Magnetic Polaron in CdSe Nanocrystals

We predict theoretically that nonmagnetic CdSe nanocrystals May possess macroscopic magnetic moments due to the formation of dangling-bond magnetic polarons (DBMPs). A DBMP is created in optically pumped nanocrystals by dynamic polarization of dangling bond spins, (DBSs) at the nanocrystal surface during radiative recombination of the ground state dark exciton assisted by a spin-flip of the DBS. The formation of DBMPs suppresses the radiative recombination of the dark exciton and leads to a temperature-dependent Contribution to the Stokes shift of the photoluminescence. This model consistently explains the experimentally observed low-temperature photoluminescence features of nonmagnetic cdSe nano crystals as manifestation's of their spin-related magnetic properties.