Light-induced spin transition in the spin-crossover complex FePt2 detected by optical pump -coherent resonant nuclear elastic scattering


We report the results of optical pump-nuclear resonance probe experiments on the SCO complex [FeII(L-PtII(t-but-tpy))2](BF4)2 with L being 2,6-di(pyrazol-1-yl)-4-(trimethylsilylethynyl)pyridine) and t-but-tpy being 4,4′,4″-Tri-tert-Butyl-2,2′:6′,2″-terpyridine using a novel experimental set-up at the beamline P01, Petra III, DESY Hamburg. We investigate the changes in the spin state of the complex when it is excited by laser pulses of 766 nm wavelength and pulse width < 100 ps. Our simulations of the nuclear forward scattering data indicate a dominant low spin state along with some high spin fraction in the absence of laser pulses. We observe clear changes in the time-spectrum following the instant at which the laser pulse hits the sample. Furthermore, these alterations are recorded as the relative timing of the laser pulses with respect to the synchrotron pulses is varied.

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This work has been supported by the German Ministry of Research (BMBF) under 05K16UKA and by the German Science foundation (DFG) via SFB/TRR 88 3MET and SFB/TRR 173 Spin+X.

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Correspondence to Sakshath Sadashivaiah.

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This article is part of the Topical Collection on Proceedings of the International Conference on the Applications of the Mössbauer Effect (ICAME2019), 1-6 September 2019, Dalian, China

Edited by Tao Zhang, Junhu Wang and Xiaodong Wang

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Sadashivaiah, S., Jenni, K., Scherthan, L. et al. Light-induced spin transition in the spin-crossover complex FePt2 detected by optical pump -coherent resonant nuclear elastic scattering. Hyperfine Interact 241, 3 (2020).

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  • Nuclear forward scattering
  • NRS pump-probe experiments
  • Spin crossover