Exchange interactions in wavefunction engineered, transition metal doped 2D hetero-nanoplatelets
Final Report Abstract
In the reporting period, we succeeded in doping two-dimensional (hetero)nanoplatelets with various transition metals (Mn, Co, Cu) and thus functionalizing their properties in collaboration with our partner. In CdS/(MnS)/Mn:CdS core-shell hetero-nanoplatelets it was demonstrated that there is an s,p-d exchange interaction between electron and hole band states and magnetic dopants. Through clever design of the architecture and doping, the electron (s-d) and hole exchange (p-d) interactions could be manipulated independently. This precise adjustability of the magnetic exchange interaction was demonstrated for the first time in colloidal nanostructures. In the second part of the project, Co 2+ was successfully incorporated into the shell of CdSe/CdS hetero-nanoplatelets. MCD spectroscopy was used to demonstrate an s,p-d exchange interaction. An assignment of the complex ligand field transitions of Co 2+ in absorption and MCD spectroscopy, as well as an explanation of their temperature behavior was developed. The last part of the work was devoted to the controversially discussed low temperature trion emission in CdSe NPL cores. It was demonstrated that a FRET process in NPL stacks strongly supports trion formation, as excitons can rapidly move to a NPL that contains a hole trap, leading to trion formation after a second exciton is excited in the same stack. This hypothesis could be verified by a targeted installation of hole traps by means of Cu doping of the NPL leading to a significant increase of trion emission. A challenge to be solved in future is the formation of a long-lived exciton magnetic polaron in CdSe-based NPLs. Basic prerequisites are the synthesis of stable Mn-doped CdTe shells and/or Mn-doped CdSe cores. Neither has yet been achieved according to our knowledge.
Publications
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Magnetically doped nanocrystals – from functionality to device development, GRC on Colloidal Nanocrystals, Smithfield, Rhode Island, US
G. Bacher
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sp-d exchange interactions in wave function engineered colloidal CdSe/Mn:CdS hetero-nanoplatelets 10th international conference on quantum dots, Toronto/Canada
S. Lorenz, F. Muckel, S. Delikanli, P. L. Hernández-Martínez, T. Priesner, J. Ackermann, M. Sharma, H. V. Demir & G. Bacher
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sp–d Exchange Interactions in Wave Function Engineered Colloidal CdSe/Mn:CdS Hetero-Nanoplatelets. Nano Letters, 18(3), 2047-2053.
Münzer, Franziska; Delikanli, Savas; Hernández-Martínez, Pedro Ludwig; Priesner, Tamara; Lorenz, Severin; Ackermann, Julia; Sharma, Manoj; Demir, Hilmi Volkan & Bacher, Gerd
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Impurity incorporation and exchange interactions in Co2+-doped CdSe/CdS core/shell nanoplatelets. The Journal of Chemical Physics, 151(22).
Fainblat, Rachel; Delikanli, Savas; Spee, Leon; Czerny, Tamara; Isik, Furkan; Sharma, Vijay Kumar; Demir, Hilmi Volkan & Bacher, Gerd
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Tailoring exchange interactions in magnetically doped II-VI nanocrystals. Chalcogenide, 271-304. Elsevier.
Fainblat, Rachel; Muckel, Franziska & Bacher, Gerd
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Collective and single spin phenomena in doped nanocrystals, SPIE Opto
G. Bacher
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Tuning Trion Photoluminescence Emission in CdSe Nanoplatelets, NaNaX 10 (Nanoscience with Nanocrystals), Klosterneuburg, Österreich
M. Riesner, F. Shabani, L. Zeylmans van Emmichoven, R. Fainblat, S. Delikanli, H. V. Demir & G. Bacher
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Demystifying Trion Emission in CdSe Nanoplatelets. ACS Nano, 18(35), 24523-24531.
Riesner, Maurizio; Shabani, Farzan; Zeylmans, van Emmichoven Levin; Klein, Julian; Delikanli, Savas; Fainblat, Rachel; Demir, Hilmi Volkan & Bacher, Gerd
