Exchange interactions in wavefunction engineered, transition metal doped 2D hetero-nanoplatelets

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Recent advances in colloidal nanocrystal chemistry allows for the realization of wavefunction- engineered nanoplatelets with core-shell, core-crown or core-crown-shell architectures. The quasi-two dimensional (2D) density of states, combined with strong quantum and dielectric confinement results in exciting electronic and optoelectronic properties, opening a pathway for innovative applications.In this project we intend to expand the functionalities of this novel material class by transition metal doping with monolayer accuracy. The required materials – which are worldwide unique - will be provided by our project partner, Prof. H.V. Demir at Nanyang Technological University, Singapore. Quasi type II (CdSe/CdS) and type II (CdSe/CdTe) heterostructures doped with manganese or cobalt in the shell / crown will represent the material basis for investigating s,p –d exchange interactions between magnetic dopants and charge carriers. Hetero-nanoplatelets with monolayer thickness control and well-defined doping positions will be investigated, where the wavefunction distribution of ground and excited carrier states will be engineered towards a targeted overlap with the transition metal dopants.The fact that in such nanoplatelets a variety of ground and excited states of different hole character (heavy hole, light hole, split-off hole) can be separated in magneto-optical experiments due to pronounced excitonic resonances will individually give access to s-d and p-d exchange constants in reduced dimensions. We intend to extract the size-dependent s-d and p-d exchange constants for both, Mn- and Co-doped nanoplatelets and envision to optically generate long living magnetic polarons with defined magnetization axis utilizing the defined architecture of type II hetero-nanoplatelets. Probing the ligand field transition of the Co2+ ion in the crystal matrix, experimental access to local strain distributions at the hetero-interface is expected by changing the dopant position with respect to the interface with monolayer accuracy.