Spin physics in colloidal nanocrystals
While spin physics is a well-developed field for epitaxially fabricated quantum dots, much less knowledge has been worked out for the spin excitations in colloidal crystals. We will give here an overview of the tools that can be used to assess and characterize the spins in these structures. With this knowledge we will give three examples for studying the spin dynamics in colloidal nanostructures: (1) We will first consider the spin relaxation dynamics of charged excitons in quantum dots and identify the underlying mechanisms; (2) then we will show how the spin dynamics can be used to assess the charging state of the nanocrystals after pulsed excitation that is often used for photo-charging; (3) finally we will study the impact of dangling bond spins at the surface of the nanocrystals on excitons in the quantum dots. Their interaction can lead to the formation of magnetic polarons, facilitating also dark exciton recombination.