Ultrafast magnetisation dynamics in a chromium-based Prussian blue analogue

Harry A. Lewis, Thomas M. Stonelake, Oscar Céspedes, J. Olof Johansson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Ultrafast transient transmittance (TT) and time-resolved magnetic circular dichroism (TR-MCD) measurements were used to investigate the electronic and magnetisation dynamics in thin films of a mixed-valence chromium Prussian blue analogue. Measurements performed for 800 nm photoexcitation unveil a TT spectrum that consists of a broad, complex, bleach-like feature with some additional excited-state absorption contributions, while the spectral dependence of the TR-MCD closely matched the shape of the static MCD spectrum. Both the TT and TR-MCD response evolved on different timescales (2.5 and 1.5 ps, respectively) and superimposed on this is a slow growth in both the TT and TR-MCD response (220 and 90 ps, respectively). Decomposition analyses of the broadband transient spectrum using temperature-dependent transmittance data indicate that the slow growth in pump-probe response is a result of sample heating following lattice thermalisation. These thermal effects have a much more profound impact on the magnetisation dynamics, particularly at high pump fluences, where the >70% loss in magneto-optical response observed after several hundred ps vastly exceeds the corresponding 4% change in transmittance. These conclusions could only be reached through the determination of both static and dynamic responses of the sample, thus illustrating the power of using complementary spectroscopic methods.

Original languageEnglish
JournalMaterials Advances
Early online date7 Aug 2024
DOIs
Publication statusE-pub ahead of print - 7 Aug 2024

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