High-Frequency EPR and ENDOR Spectroscopy of Mn2+ Ions in CdSe/CdMnS Nanoplatelets

Roman A Babunts; Yulia A Uspenskaya; Nikolai G Romanov; Sergei B Orlinskii; Georgy V Mamin; Elena V Shornikova; Dmitri R Yakovlev; Manfred Bayer; Furkan Isik; Sushant Shendre; Savas Delikanli; Hilmi Volkan Demir; Pavel G Baranov

doi:10.1021/acsnano.2c10123

High-Frequency EPR and ENDOR Spectroscopy of Mn²⁺ Ions in CdSe/CdMnS Nanoplatelets

ACS Nano. 2023 Mar 14;17(5):4474-4482. doi: 10.1021/acsnano.2c10123. Epub 2023 Feb 20.

Authors

Affiliations

¹ Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia.
² Kazan Federal University, Institute of Physics, 420008 Kazan, Russia.
³ Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany.
⁴ Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey.
⁵ Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, School of Materials Science and Engineering, Nanyang Technological University, 639798 Singapore.

PMID: 36802485
DOI: 10.1021/acsnano.2c10123

Abstract

Semiconductor colloidal nanoplatelets based of CdSe have excellent optical properties. Their magneto-optical and spin-dependent properties can be greatly modified by implementing magnetic Mn²⁺ ions, using concepts well established for diluted magnetic semiconductors. A variety of magnetic resonance techniques based on high-frequency (94 GHz) electron paramagnetic resonance in continuous wave and pulsed mode were used to get detailed information on the spin structure and spin dynamics of Mn²⁺ ions in core/shell CdSe/(Cd,Mn)S nanoplatelets. We observed two sets of resonances assigned to the Mn²⁺ ions inside the shell and at the nanoplatelet surface. The surface Mn demonstrates a considerably longer spin dynamics than the inner Mn due to lower amount of surrounding Mn²⁺ ions. The interaction between surface Mn²⁺ ions and ¹H nuclei belonging to oleic acid ligands is measured by means of electron nuclear double resonance. This allowed us to estimate the distances between the Mn²⁺ ions and ¹H nuclei, which equal to 0.31 ± 0.04, 0.44 ± 0.09, and more than 0.53 nm. This study shows that the Mn²⁺ ions can serve as atomic-size probes for studying the ligand attachment to the nanoplatelet surface.

Keywords: CdSe nanoplatelets; colloidal nanocrystals; diluted magnetic semiconductors; electron nuclear double resonance; electron paramagnetic resonance.