Probing photoinduced spin states in spin-crossover molecules with neutron scattering

K. Ridier, G. A. Craig, F. Damay, T. Fennell, M. Murrie, G. Chaboussant

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Abstract

We report a neutron-scattering investigation of the spin-crossover compound [Fe(ptz)6](BF4)2,which undergoes
an abrupt thermal spin transition from high spin (HS), S = 2, to low spin (LS), S = 0, around 135 K. The HS
magnetic state can be restored at low temperature under blue/green light irradiation. We have developed a
specially designed optical setup for neutron scattering to address the magnetic properties of the light-induced
HS state. By using neutron diffraction, we demonstrate that significant HS/LS ratios (of up to 60%) can be
obtained with this experimental setup on a sample volume considered large (400 mg), while a complete recovery
of the LS state is achieved using near-infrared light. Finally, with inelastic neutron scattering (INS) we have
observed magnetic transitions arising from the photo-induced metastable HS S = 2 state split by crystal-field and
spin-orbit coupling.We interpret the INS data assuming a spin-only model with a zero-field splitting of the S = 2
ground state. The obtained parameters are D ≈ −1.28 ± 0.03 meV and |E| ≈ 0.08 ± 0.03 meV. The present
results show that in situ magnetic inelastic neutron-scattering investigations on a broad range of photomagnetic
materials are now possible.
Original languageEnglish
Article number094403
Number of pages6
JournalPhysical Review B
Volume95
Issue number9
DOIs
Publication statusPublished - 3 Mar 2017

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Keywords

  • photoinduced spin states
  • neutron scattering

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