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 nanocrystals as manifestations of their spin-related magnetic properties.
†Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia.
Anna
A
Rodina
‡Naval Research Laboratory, Washington, DC 20375, United States.
Alexander L
AL
Efros
CdSe; Dark exciton; dynamic polarization; magnetic polaron; nanocrystal; spin flip