Organic chromophores on ferromagnets illuminated: photochemical and magnetic study

• Applicant: Dr. Aleksandra Lindner
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 464974971

Within the recent years molecular spintronics based on inorganic/organic interfaces received a lot of attention. Unique magnetic phenomena, including spin filtering, manifest themselves at such spinterfaces. As shown recently, chiral organic molecules themselves are capable of spin filtering (chiral-induced spin selectivity effect - CISS). Moreover, once grafted on the surface of metal, they can change its magnetic properties (magnetism induced by proximity of adsorbed chiral molecules - MIPAC). Even though molecular spintronics is a vividly developing field, surprisingly little has been done to explore its potential in combination with advantages offered by the light-induced processes in organic chromophores. Therefore, the main focus of this project is to fabricate inorganic/organic hybrids by self-assembly of chromophore-containing organic molecules onto the chosen thin ferromagnetic films (FM) with the ultimate goal of probing/detecting in the designed systems spin-polarized (spin-selective) photoinduced electron transfer and its influence on the faith of the photoexcited chromophore and dynamic magnetic properties of the underlying ferromagnet. Such a scientific goal of the project imposes the necessity of using a twin-track approach to the planned studies: on one hand investigating photochemistry of the excited chromophores once bound to the ferromagnet and on the other hand exploring light-induced changes in the magnetization dynamics of the chromophore-modified FM thin layer. Organic molecules of choice (chiral and non-chiral) will be immobilized on the FM surface forming self-assembled monolayers (SAM). The structure of the molecular layer will be elucidated using various surface-sensitive methods. Subsequently, photochemistry of the FM-bound chromophores will be investigated using combination of the absorption and emission techniques, both in steady-state as well as in time-resolved regime. Magnetization dynamics of the chromophore-modified FM thin layer in dark and under light illumination will be probed using microresonator-based ferromagnetic resonance (micro-FMR), a technique perfectly suited to directly pick up the results of spin-polarized electron transfer into or out of the magnon system, while being fully compatible with light illumination.We believe that this project due to twin-track approach and choice of the experimental methods will allow to elucidate the nature of the photochemical and photophysical processes occurring in the organic chromophore/ferromagnet hybrids. As such it will significantly contribute to extend the already existing knowledge concerning the light-induced processes in hybrid inorganic/organic systems. Moreover, it will open new avenues for the study of light-accompanied phenomena in such hybrid structures. Consequently, it will effectively bring closer the realization of the synergy between photonics and molecular spintronics paving a way to optically controlled magnetic systems in the future.

• DFG Programme: Research Grants
• International Connection: Poland
• Cooperation Partner: Professor Dr. Bronislaw Marciniak