cfm seminar - Spin-crossover molecules at surfaces

CFM Seminars

Speaker

Vincent Repain
Université Paris Cité

When

2026/06/18
11:00

Place

CFM Auditorium

Host

Enrique Ortega (CFM)

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Spin-crossover molecules at surfaces

Spin-crossover molecules are inorganic compounds showing the unique ability to switch between two spin states, generally a low spin diamagnetic one and a high spin paramagnetic one. This change of magnetic properties is also accompanied in the bulk by a change of optical (colour, index…) and mechanical (volume, Young modulus…) properties. Recently, it has been proposed that such molecules could be used in electronic devices to make either non-volatile memories or multi-functional devices, exploiting their multi-stimuli responses. The prerequisite to develop such devices is to understand the behavior of those molecules in contact with metallic substrates. We have studied by scanning tunneling microscopy (STM), grazing incidence x-ray diffraction and x-ray absorption spectroscopy how a single layer of molecules self-organizes on different surfaces (Au, Cu, Ag, Co) and how the thermal and light-induced switching properties are modified by the epitaxy with the substrates [1-6]. Interestingly, whereas in the bulk the switching occurs through cooperative mechanisms, we have been able on surfaces to address every molecule individually with the STM tip, modifying their spin state [7]. The readout is done through a conductance map, which is drastically different for the two spin states, with a strong negative differential conductance which can be explained by an orbital dependent Coulomb blockade mechanism [8].

[1] K. Bairagi et al., Nature Communications 7, 12212 (2016)

[2] L. Zhang et al., Angewandte Chemie Int. Ed. 59, 13341 (2020)

[3] M. Kelai et al., Journal of Physical Chemistry Letters 12, 6152 (2021)

[4] M. Kelai et al., Journal of Physical Chemistry Letters 14, 1949 (2023)

[5] A. Reilan et al., Physical Review B 107, 014304 (2023)

[6] A. Bellec et al., Journal of Physical Chemistry Letters 17, 5223 (2026)

[7] Y. Tong et al, Journal of Physical Chemistry Letters 12, 11029 (2021)

[8] D. Li et al, Journal of Physical Chemistry Letters 13, 7514 (2022)