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Vibrational Coherences in Manganese Single-molecule Magnets after Ultrafast Photoexcitation

preprint
submitted on 19.12.2018 and posted on 19.12.2018 by Florian Liedy, Robbie McNab, Julien Eng, Ross Inglis, Thomas Penfold, Euan K. Brechin, Johan Olof Johansson

Single-Molecule Magnets (SMMs) are metal complexes with two degenerate magnetic ground states arising from a non-zero spin ground state and a zero-field splitting. SMMs are promising for future applications in data storage, however, to date the ability to manipulate the spins using optical stimulus is lacking. Here, we have explored the ultrafast dynamics occurring after photoexcitation of two structurally related Mn(III)-based SMMs, whose magnetic anisotropy is closely related to the Jahn-Teller distortion, and demonstrate coherent modulation of the axial anisotropy on a femtosecond timescale. Ultrafast transient absorption spectroscopy in solution reveals oscillations superimposed on the decay traces with corresponding energies around 200 cm−1, coinciding with a vibrational mode along the Jahn-Teller axis. Our results provide a non-thermal, coherent mechanism to dynamically control the magnetisation in SMMs and open up new molecular design challenges to enhance the change in anisotropy in the excited state, which is essential for future ultrafast magneto-optical data storage devices.

Funding

Royal Society of Edinburgh

Carnegie Trust collaborative grant

EP/P025986/1

EP/N01331X/1

EP/R021503/1

EP/P012388/1

History

Email Address of Submitting Author

olof.johansson@ed.ac.uk

Institution

University of Edinburgh

Country

UK

ORCID For Submitting Author

0000-0002-9320-447X

Declaration of Conflict of Interest

The authors declare no competing financial interests.

Version Notes

Version 1 of the manuscript.

Exports