Spin dynamics of carriers interacting with dangling bond spins in colloidal semiconductor nanostructures

Non-magnetic colloidal nanostructures can demonstrate magnetic properties typical for diluted magnetic semiconductors because the spins of dangling bonds at their surface can act as the localized spins of magnetic ions. This idea has been suggested theoretically to explain the recombination mechanism of spin-forbidden dark excitons in colloidal nanocrystals [1]. We aprove it experimentally for CdSe colloidal nanocrystals [2]. Spins of dangling bonds indeed activate emission of the dark exciton. Also their collective interaction with the exciton results in formation of the dangling-bond magnetic polaron, which parameters are examined experimentally and theoretically. In CdSe nanoplatelets presence of the dangling bond spins is visualized via strong polarization of excitons in external magnetic field. [1] A.V. Rodina and Al. L. Efros, Nano Lett. 15, 4214 (2015). [2] L. Biadala, et al., Nature Nanotechnology 12, 569 (2017).